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MG MGB Technical - Oil Change Frequency
| Most oil companies and many mechanics recommend motor oil changes at intervals of the lesser of three months or three thousand miles. I have two cars that will travel less than three thousand miles in six months and I feel a little guilty for not changine the oil more frequently (my other cars are changed at the 4,000 mile mark - usually 2 1/2 months) Is the old spring and fall change good enough - i'm using Mobil 1 15w-50 with a K&N filter (HP2004)? rn |
| RN Lipow |
| RN, I change mine in spring and mid-summer, usually after about 3000 miles. Oil & filter arn't very expensive, and it's cheap insurance! |
| Robert Dougherty |
| I, for one, have a conflicted view of oil changes. The manufacturers of engines typically say a frequency of 6-7 thousand miles or 6-7 months is more than adequate for a car driven in a typical fashion. I think the Jiffy Lubes and the oil companies would love us all to believe we need to change our oil every three tousand miles because they make money every time we do. But then it is so gratifying to take extra good care of an engine you want to have around for a long time. So what do I do, myself? The B roadster: change every 6 months (less than 3K miles). The B-GT autocrosser: change every two months whether it needs it or not. This usually amounts to about 1000 miles per change. I imagine a typical B motor needs an oil change every six months, assuming the milage is only a few thousand miles or less, anyway. I've always thought Synthetic oils stand up even better. I change the Mobil 1 in my wife's car every six months, with about 8K highway miles on the clock. Even at that point, my main concern is the filter. Dean |
| Dean Lake |
| Recommended oil change intervals are usually given for "normal" and "severe" conditiions. What most people don't understand is that severe conditions is what most cars are put through, including our MGs. Cars that are driven 10,000 miles a year, mostly on the freeways and always on trips of more than 10 miles are the ones, whose engines have it easy. The engines on these cars are being heated up enough to drive all of the moisture and acids out of the oil and can be safely run for the 6000 - 7000 mile interval suggested (for late model cars). Cars like ours, that are driven mostly on short trips, to and from club meetings or to and from shows, trips that are short in duration and don't get the engine heated up to normal operating temperatures for long period of time, wind up with a lot of moisture (from condensation) and acid (moisture combined with combustion components) built up in the oil and should be following the severe use oil change interval. I look at 3000 mile or 3 month interval as a good one to use with our MGs. Even if the car is driven very little, the oil should be changed every three months, unless the car is stored for the winter,in which case the oil should be changed before the car is laid up and again when it is brought out of storage. These intervals would apply equally to synthetic oils because we are worried about the buld up of contaminates in the oil rather than how long the oil holds up. Steve S. - How about your thoughts on this? Cheers - Dave |
| David DuBois |
| I,ve had my MG-B for 14 months and put just over 1000 miles in that time frame. I do make sure I put 15 to 20 miles on at one leg to make sure the engine has heated up the crankcase and recharge the battery. Now how often should I change my oil and what viscosity should I use? The engine is still the original factory except carb & exhaust with 95k logged on the odometer. cheers, Gary |
| gary n. hansen |
| Gary, I suggest Castrol GTX 20-50 and change it every 6 months, with your usage. That would be square with the official MG factory general specifations, which didn't even take into account the advances in motor oil we have enjoyed over the last 30 years. I don't honestly believe the brand of oil matters a lick, anyway, these days; if it is being changed on a schedule appropriate to its usage, its limitations aren't even being tested. I use GTX just because I always have, not because it is demonstrably superior. Does anyone even know how many refineries there are, anyway? Can there really be as many different quality levels within industry guidelines as there are brands? If we have any petroleum pros out there who know the inside skinny it would be interesting to know. Dean |
| Dean Lake |
| My two MGB's are insured as classic cars with some driving restrictions. There are no nearby club functions so when the cars are driven the run is usually over 50 miles. I change the oil and filter (Castrol GTX 20-50) every six months. I also agree that the brand of oil is not critical and on my modern cars I use a name brand oil but buy sale items so the brand may vary. Never had an oil related problem. I will not install a Fram filter on any of my vehicles. FWIW, Clifton |
| Clifton Gordon |
| Gary- The best petroleum-based oil for an MGB is Castrol 20W/50 and the best synthetic oil is Mobil 115W/50. I use the former in my transmission and the latter in my engine. Why don't I use the less expensive Castrol in my engine? Simple: most of the wear that takes place in an engine occurs during the warm-up period because the oil is too thick to flow easily. Once the engine gets up to operating temperature, it flows freely and does its job well. The Mobil 1 synthetic flows just as well cold as it does when it's hot. It also doesn't thin out at high temperatures, which is a serious plus in an engine that's been modified for higher power output. Why don't I use it in my transmission? Because the transmission seems to shift a bit better with the Castrol oil. Go figure! How often should you change your oil? Read on- David- All of your comments on acid buildup and condensation are right on the money. However, there's another factor that needs to be mentioned: the effects of blow-by. Just because a wet compression test may give readings that seem up to par doesn't automatically mean that the compression rings are doing an adequate job of containing the enormous pressures of combustion. When partially burned fuel blasts past the rings and onward into the crankcase, the oil becomes contaminated with carbon, one of the hardest substances known to man and the enemy of all precision-machined surfaces. It's the stuff of which a blueprinted engine's nightmares are made of. How to tell the condition of the compression rings without putting the car on a dynometer and running it against a heavy load? Simple: If your oil turns an opaque black within 3,000 miles, you've got a problem. How to protect that big investment that you've made in your newly rebuilt honey? First, be picky when it comes to your choice of oil. Use only the best. True, as Clifton points out, you can use lesser quality oil and never experience an oil-related failure. Today's oils are far better than what was available thirty years ago, and outright failures that are oil-related are all but unknown today. Nevertheless, a better oil can mean a longer engine life. Second, always change the oil filter whenever you change the oil, and use the best oil filter that you can get. The fewer solid particles there are circulating inside your engine, the better. The top oil filters right now are the Mann (Part# W917), Purolator Pure One (Part# 10017), Motorcraft (Part# FL300), but the most effective is also the easiest to install: the K&N Performance Gold Oil Filter (K&N Part # HP2004). Clifton won't use a Fram oil filter. Neither will I. Third, be ruthless when it comes to oil changes. If the oil is opaque, change it. If it has 3,000 miles on it, change it. If it's been in the engine for six months, change it. If you're putting the car in storage for the winter, change it. When you change the oil, don't be hasty and replace the drain plug when the drain flow slows to a drip. If you put a measuring cup under the drip and wait a couple of hours, you'll get about twelve additional ounces of the nastiest, grittiest stuff you'll ever have the displeasure to see coming out of an engine. This cr@p will wear out your engine. Get all of that old oil out. True, you don't have to be as fanatical as I am. You can use ordinary oil, ordinary filters, change your oil as quickly as you can, and still expect to get a good 80,000 miles out of your engine. Today's oils really are that good. But personally, I figure that if I don't get at least 140,000 miles out of an engine, then it's a lemon. To me, 180,000 miles is more reasonable. |
| Steve S. |
| Steve. Yes, you are a fanatic, but, we still love you. I agree with you. Bob Wilson, who used to post regularly and lived up in Canada, was a petroleum engineer. He wrote me that he had tested regular motor oil (Castrol, I believe) and Mobil 1 by placing them in the freezer, then pouring them out of the container. He noted how much easier and faster the Mobil 1 flowed as compared to regular motor oil. You and I have both rebuilt a number of engines over the years and realize exactly how much work is involved, as well as how expensive it can be if done right--expensive in money and time. I change my motor oil every three months. I change my transmission and rear end fluids (Castrol 20W-50 for the former and 90 weight gear oil for the latter) every two years. This service routine is probably more "pro-active" than is necessary. But, I bought my Bronco in 85 and my MGA in 78. I hope to keep my MGBs just as long and enjoy driving them with confidence. I purchase my Mann oil filters, a dozen at a time, from the assistant manager of my local BAP store. He is a former MGB owner and gives me a good price for them. Four oil filters per year and 16 quarts of oil cost me under $50. If I can extend my engine life by a couple of years by making this very small investment, I am more than happy to do so. Les |
| Les Bengtson |
| Hi, Gotta get my two cents worth here. I use a litre of Slick 50 in my Engine and change oil once a year usually about 2000-4000kilometers. Only use Slick50 every 50,000kilometers and change oil as mentioned above. I would change oil every 5,000KLms (3000Miles) if I drove that much in a year. I have 92k on my engine and it don't burn any oil between changes Cec |
| Cec |
| Speaking of slick 50, what do you guys think of all these oil additives, are they useful? I don't use them, but I did use STP when I was a kid, my hot rod days. |
| Stan Williams |
| Steve: Thanx for the info. Point of discussion about Mobil-1 et al synthetics. I've heard NOT to use this lubricant in older unrestored engines as it may cause seals to leak and remove the carbon build-up from the rings that has accumulated over the years. I have personally used Mobil-1 in previously owned cars and did notice the engines ran quieter (not noticable to the untrained ear) as well as winter start up seemed to be more "agreeable" to the car. Also, an inspection under the valve cover revealed an immaculate engine environment. Quite pleasing Clifton & Steve: What is the squawk with Fram filters? You guys are the first ones I have heard any comments about Fram. I have not had a problem with any brand actually. What is a good filter for the MG-B 1979 vintage? Stan: I have mixed feelings about oil additives. I am not an engineer by education or training, but I have yet to hear or experience, any substantiated comments to the pro side of using an additive. I have seen the sludge build up in a 1970 350 Chevy that was subjected to 70k miles of STP additives. The stuff finally choked the oil supply lines to the crank bearings. We scooped the stuff out from under the pushrod / camshaft cover plate. Thanx to all cheers Gary |
| gary n.hansen |
| Steve S / Les - I notice you both mention how much easier Mobil 1 flows at cold temperatures. I guess I don't understand. If the "15w" in the "15w/50" means the oil flows at a certain rate in cold weather service how/why should one brand flow better than another if they both have the same SAE rating? Thanks! Greg |
| Greg Smela |
| With regard to Mobil 1 I have noticed that the cold start oil pressure is not very far off from the pressure reading during warm idle. It appears to flow well from the start and does not "peg" the oil gauge when cold. rn |
| RN Lipow |
| Filters! There is more to an oil filter then just filtering. Consumer reports has said many times that fram filters the best! But I have found there cheap and chenzy with there check valves. On a typical B with inverted filter this is very important. Your back to a long time for pressure buildup with Fram. I am sold on Wix but not the one they currently call for as it's to tall. 51521 is the one to use. I use Chevron Supreme syn 15w 50 in Dee's Gt which now has 53,000 in two and a half years. Also I went to a fill side up filter to cut any pressure buildup time. Bob Thompson/International Auto |
| Bob Thompson |
| You are all talking of 20w 50 and synthetic 15w 50. What about synthetic 5w 50? Should be even better - or are there any disadvantages? Tore |
| Tore |
| Gary, there should be some information in the archives about Fram filter quality. I recall two or three threads on them during the past two years. Information about filter construction can be found at; http://www.scuderiaciriani.com/rx7/oil_filter_study/ I have never used a Fram on my MG's, but have used many of them on other cars. In 1979 I bought a Honda Accord, no dealer in town, so I bought a Fram filter and installed it. It started getting a valve train rattle on cold engine startups, going back to Honda filters stopped the rattle. My son had the same problem with Fram filters on a 1991 Isuzu Stylus XS, switching to a Purolator stopped the rattle. My last problem was a Fram ToughGard on my 1999 Nissan pickup. I would get a bad rattle on most startups, switching back to a Nissan filter stopped the rattle. I sent Allied Signal an email about the Nissan filter problem. They asked for the filter and sent me a shipping kit to send it to them. I mailed the filter to them and about four or five weeks later reported that in the lab test the pressure function passed the test but the anti drain back valve failed. They did not know the reason. Allied Signal did send me three new filters but I didn't use them. THey were supposed to do some more research but I never heard anything more from them. In addition to the three above reference to my use of Fram filters, I used them on three Nissan Sentras I owned between 1987 and 2002 and never had a problem with one on a Sentra. I stopped using them on the last Sentra in 2000 after the pickup problem. Steve made some excellent suggestions on the best filters to use. I recently learned that CarQuest filters are made by Wix. If you do a search on, "Fram filter failures" you will find examples of problems with Fram filters on lots of different vehicles. So what do I use on the MG's, Unipart, Motorcraft FL 300 or Purolator. FWIW, Clifton |
| Clifton Gordon |
| Stan- Don't waist your money on oil additives. They were a good idea when they were introduced back in the dark ages of motor oil, but modern oils already have them in them. Gary- Mobil 1 does not "cause" leakge in and of itself. It is highly detergent in nature and will remove sludge quite effectively. Old cork gaskets deteriorate and often it is only the baked-in oil that is holding them together and the old sludge that is doing the sealing. It also has the wonderful property of getting into everything, so if seals are shot, leakage can occur. The problem with Fram filters is just what Clifton described: a terrible leakdown valve design. It's nothing more than a plastic flap. The oil leaks out of the filter, so you have to wait for the oil pump to pump enough oil into the filter to fill it before you can get any real oil pressure inside the engine. In the meantime the bearings (and everything else inside the engine) are taking a hell of a pounding, just as if the oil pump had failed. You can imagine what I think should be done to the fool who designed that one! You asked which oil filters are good for the MGB so I'll repost: The top oil filters right now are the Mann (Part# W917), Purolator Pure One (Part# 10017), Motorcraft (Part# FL300), but the most effective is also the easiest to install: the K&N Performance Gold Oil Filter (K&N Part # HP2004). I use the K&N, despite the fact that it's the most expensive and filters no better than the runner-up Purolator. Why? Ease of removal! It has a hexagonal projection on top that's perfect for a socket. |
| Steve S. |
| I agree wholeheartedly with Steve. I use Castrol 20/50 and change my oil and filter every 3000 miles. My current engine went 200,000 miles before it was rebuilt and has 120,000 miles on the rebuid and is still going strong. My 73 BGT is my everyday car. My one departure is that I've used a teflon oil additive called Tufoil for the life of this motor (after the original first 30K). I do think that most additives are unnecessary, if not harmful, but I've had a lot of discussions with the Tufoil techs over the years and have confidence in this stuff. I believe that the Tufoil provides lubrication to the engine at startup until the oil start circulating. My question for Steve is that what he thinks of the Unipart filters. I've been using them for years. Steve L. |
| Steve Lipofsky |
| I have a S-10 with 160,000, a Stealth with 145,000 a Suburban with 158,000 and a 78 MGB with 108,000 miles. I change the oil on all of them at 2500-2750 miles. On the MG, since it is not a daily driver, this amounts to about every 2 1/2-3 months. Almost all my evening and weekend drives are 80+ miles. I use Havoline oil of varying weights and Fram filter on all of them. We bought a new Suburban 11 months ago and it now has 22,000 miles and gets the same treatment as the others. |
| Jimmy Chew |
| Steve- I haven't used Unipart filters for many years, but not because I dislike them. I don't know how fine a particle that they will filter out, but they were good enough for MG to use them as Original Equipment, so I presume that they must be OK. Anybody out there know how fine a particle that they will filter out? |
| Steve S. |
| it is my understanding that the synthetic lubricant does not "wear out" that the purpose for changing it and the filter is to remove contaminants such as dirt, gas, water, metal particles. I have heard that there is research going on to make engine lubrication "permanant" so that only filters will be changed. rn |
| RN Lipow |
| Someone mentioned oil additives. The Vintage Triumph Register (I know, heresy) has a good article on the subject. http://www.vtr.org/maintain/oil-additives.html The conclusion they came to was; most (not all) did no harm, but none did any real good. If the magic ingredients really had any value, the oil companies would be putting them in the oil and the engine makers would be insisting on them. One thing that I find very telling is that many, including Slick 50, contain PTFE, which is the abbreviation for the chemical name for Teflon. Notice that Slick 50 (or any of the others) does not mention Teflon. That is because DuPont, which owns the patents and trademarks for Teflon, believes that it has absolutely no automotive application. They refused to sell PTFE to oil additive makers at first, but were forced to as a result of a restraint of trade lawsuit. They do not allow the name Teflon to be used. If PTFE were so great for cars, don't you think that DuPont would be pushing it to the major oil producers, as a way of increasing the sales of the stuff? PTFW does not dissolve in oil. It is a particulate. What do oil filters do? They filter out particulates! Deliberately putting particulates into your oil seems counter productive to me. You're just asking for clogged filters. |
| Paul Noble |
| When synthetic oil first became available it was claimed by many that oil changes could be extended to 25,000 miles and beyond, but I haven't seen any recent ads claiming extended oil change with synthetics. On that note, a few years ago a local service station told me thay had a traveling salesman customer that drives 100k per year, he buys a new Honda every two years and never changes the oil, he adds oil as needed and at that time had never had an engine failure. Around 20 years ago when my son was racing go karts I tried some PTFE in the engines, 5hp Briggs and Stratten (sp?). As I remember it turned the aluminum parts black, it was supposed to increase power but we never noticed any power increase, but it didn't hurt anything other than making a mess and taking a few dollars out of my pocketbook. FWIW, Clifton |
| Clifton Gordon |
| Interesting comments about oils and filters. Can anyone tell me where Mann filters are available? Thanks, Jack L. |
| Jack Landis |
| Jack -- The Mann W917 fits almost all 80s-90s Volvos (and maybe even current production as well...), so try an aftermarket (i.e. non-dealership) Volvo shop. Steve -- I've been using the Purolator Pure One 14670, which I think I arrived at by looking up a mid-eighties Volvo. I've been quite pleased with them -- they've got a nice synthetic anti-drainback valve and are larger in diameter than a GFE-121 (but the same height). I'm curious now about the 10017 you mention. Can you tell me more? Or would I learn more by stopping at Pep Boys on my way home? Cheers! Rob |
| Rob Edwards |
| Curiosity got the better of me, so I stopped by Pep Boys on my way home. They didn't have a Pure One PL10017, only a Premium Plus L10017. I compared this filter with a Pure One PL14670, and to the naked eye, the difference is..... nothing. They are the same diameter, the same height. Both have anti-drainback valves. Both have the same sized seals, and I'm sure both use the same thread. So now I'm even more confused -- it doesn't make sense that Purolator would produce two identical filters (ok -- filter sets: L10017/PL10017 and L14670/PL14670) under different numbers. If anything, economy would dictate they collapse applications to as few part numbers as possible. The only difference then that I can imagine would be in the filter media itself. Time to cut open some filters, I guess! |
| Rob Edwards |
| Rob, You can find some information about Purolator filters on their web site.at; http://www.pureoil.com/ When you check application and get to MGB they show PL20081/L20081 as the correct filter. I think this may be a long/tall filter. I have a L10017 in front of me and when I click on the "You have a filter but don't know what it fits", MGB comes up along with 12 screens of other applications. When I entered L14670 I get about 34 screens of Chrysler, Ford, Volvo, etc. but no mention of MGB. I also have an unused MotorCraft FL 300 and the Purolator L10017 is about 1/4" shorter than the FL 300. The height of the Purolator was of some concern to me so I measured the filter adapter standpipe and the inside depth of the L10017 and it has ample clearance above the standpipe more than 1/2 " as I recall. Since you have been using the PL14670, it must be ok even though I cannot find anything in their web site to support it's fitting an MGB. Just when I thought I had the filter situation figured out along comes this thread, showing there is still more to learn. Regards, Clifton |
| Clifton Gordon |
| Rob- I now know that Purolator has changed the part numbers because I still have the old box that the filter came in (it says PL10017). I went down to a nearby Avance Auto store and took a look just to make sure that maybe they carry the Purolator Pure One PL10017 while Pep Boys doesn't. Sure enough, the Pure One PL10017 is no longer carried or listed, but, just as you found, there is a Premium Plus L10017. The propaganda on the Pure One box says that it filters out 98% of all particulates, while that of the Premium Plus box says that it filters out 96%! I looked at them (L10017 and PL14670) very closely inside and out and the only differences that I could detect by visual examination was the external color (Blue vs White) and the color (otherwise identical) of the gaskets and the anti-drainback valve (Red vs Black). Even the stamping numbers were the same! Interestingly, the shell of the Pure One has changed from aluminum to steel. Could it be that Purolator is deliberately under-rating their less expensive Premium Plus filter ($2.79) so that they can charge more ($5.99) for their Pure One filter? I checked their cross-reference book and found that the PL14670 that you mention isn't listed for the MGB, but the PL20081 is, just as Cliff said. Personally, I haven't used a Purolator Pure One filter on my B since summer of last year. My only dislike of it was that it had a shell that was made of thin aluminum. When I tried to remove it it, it started to collapse and I had to drive a screwdriver through it and pray that it didn't tear apart as I forced it open. I got it off, but just barely! I've used the K&N filter ever since. |
| Steve S. |
| Thanks for the info, Clifton. I looked at the listing for Volvos while I was at the store, and L14670 was listed for 1978-1995 all (except diesel). I keep referring to Volvo because I have seen numerous reference to Mann W917 being a suitable MG filter, and W917 was what we stocked at the Volvo shop... It didn't occur to me to look at the MGB listing because I didn't want Purolator's version of a GFE-121 when I knew there were larger filters that work. Another filter that I have used in the past is a Bosch filter that is a replacement for the now-superceded Range Rover ERR-1168. The RR part was replaced by ERR-3340, which is the same diameter but about half the length. Bosch still make a long version (the part number escapes me for the moment). I stopped using it because I was concerned that extra length allowed too much oil to drain back into the sump and thus the time to prime it was too long. (The filter stood a good several inches above the standpipe...) Although if one were to extend the standpipe.... |
| Rob Edwards |
| Steve, I was using the Pure One based on the findings cited in the famous oil filter study. But based on what you've found, the Premium Plus may be as good if not better for half the price! I think the difference in the color of the rubber seal and anti-drainback valve is due to silicone rubber versus conventional rubber. I didn't mention is before as it is a feature of the product line, not the application. But it is a difference between the two... Curioser and curioser... |
| Rob Edwards |
| The period Drivers Handbook for the MGB states 6,000 miles or 6 months for things like the oil and filter, and 12,000 miles or 12 months for other items. |
| Paul Hunt |
| A comment on the importance of proper filtering of the oil: Looking through some MG papers yesterday, I was reminden of an experiment that was done with the everyday car of one of our former local chairmen, while he was working for Mobil. For 90.000 kilometres (60.000 miles) he was driving on the same synthetic oil. (Mobil 5W/50, I believe) Only the filter was changed every 15.000 kilometres (10.000 miles). When the engine was dismantled for inspection, there was no measurable wear! That shows how good a modern, synthetic oil is if it is kept clean. Tore |
| Tore |
| 'Cept 5W/50 is not good for 'older' engines that were manufactured with bigger tolerances, let alone wear. |
| Paul Hunt |
| I've used the Purolator 14670 and it works fine. At a friend's recommendation, I switched to a Unipart, but it seems to take longer for my oil pressure to come up on starting. Perhaps I just got a bad filter. I used to always use Frams on my subaru. I keep reading bad things about them though. Oil changed earlier of 3 months or 3000 miles. Also, I sold the car with 160,000 miles and understand that the new owner had to replace the engine. I don't know if the filter was to blame, but I took very good care of that car. |
| Greg Bowman |
| There's an interesting study at: http://www.scuderiaciriani.com/rx7/oil_filter_study/ This was done by an amateur, but he tried to be conscientious and thorough. He bought as many brands of filters as he could find and cut them open to reveal, among other things, the total area of the filter medium. Interesting reading. Regarding the extended life of the synthetics, I remember years ago, back in the early seventies, when synthetics were relatively new, that they used to advertise 25,000 or 30,000 between oil changes. The problem was that the car makers insisted that such extended use without an oil change voided the warranties on the engines. The synthetic makers may have stopped pushing the long intervals for fear of lawsuits from angry car owners who had to pay for replacement engines. |
| Paul Noble |
| From what I understand, the petroleum base does not wear out. The problem is due to contaminants introduced from the outside. The oil filter cannot possibly caputre it all and store it. This introduces the other part of the dicussion. What to do with the waste oil?? I've heard it is used to create tar for paving roads. The quick oil change place uses it for heating fuel. I wonder if the waste oil can be re-refined to use once again for it's original engine use? Just how "clean" can re-refined oil get? The thought process goes on and on. cheers Gary |
| gary n.hansen |
| Ok, please don't get upset or belittle me for this response. I remember hearing or reading somewhere, that in the past (usually) farmers would take all of their old oil and put it in a barrel place a bit of rope in said barrel with oil and drape it over a raftor with the other end in an empty barrel. Apparently the rope wicked up the oil and would clean out the contaminents and put 'clean' oil in the empty barrel. If memory serves this was to save money (I believe it was probably after the depression era). Zach ps yeah I know this sounds a little crazy. |
| Zach |
| Paul, Iīm not that much of a technician, but I donīt quite understand why 5w/50 oil should not be suitable for our old engines. Of course wide tolerances and wear demand an oil with more body than, say a modern 0W/40. But when the 5w/50 is cold, it is certainly thicker than hot 20w/50, and when hot - well, itīs a 50 grade, just like 20w/50? Right? Or wrong? Tore |
| Tore |
| Not being a petroleum engineer, I only know what I read. "Straight weight oils", such as SAE 30, are pure petoleum and only go bad due to picking up "by products of combustion". Such oils may be "remanufactured", a process in which the contaminates are removed and the original properties of the oil are restored. One article, read back in the 60s in Popular Science, claimed that the US Air Force was using the "remanufactured oils" in their jet aircraft. I cannot say, from personal experience, whether this is true or not. My understanding, once again from reading, is that the "mulit-viscosity" petroleum based oils have synthetic "viscosity improvers". These viscosity improvers are plastic "chains" which tend to become more dense when heated, thus raising the "weight" or "viscosity" of the oil. The articles I have read state that the "chains" will break down over time, reducing or eliminating the ability of the oil to thicken. This may mean, that after a certain point, you are running an oil of lower viscosity (a measurement of its ability to flow) than is desirable for that particular engine. The containment of contaminants which cannot be filtered out and the loss of ability to thicken properly would seem to be the reason that mulit-grade oil should be changed on a regular basis. As to the flow properties of Mobil 1 as opposed to normal, petroleum based, motor oils, I would suggest that Bob Wilson's experiment is a very simple one to replicate. He placed a bottle of each in his freezer, the poured them out. A couple of old coffee cans would work well as recepticles. Bob is a trained petroleum engineer and found enough difference that, when living in Canada, he decided on Mobil 1 in his MG. Here in Arizona, I use Castrol 20W-50 year round, Mann W917 Oil Filters (bought in bulk from my local BAP store) and change the oil every 3K miles. At best, I am prolonging the life of the engines in my cars. At worst, I am spending less than $100 per year in excessive oil changes. I am willing to live with this. Les |
| Les Bengtson |
| Doesn't the 5 in 5W indicated that it has much better cold flow characteristics than a 20W? I.e. thinner when cold? My comment was based the manufacturers own recommendations, who if anything would be keener on everyone buying the very expensive grades rather than numbers of us buying the cheaper. |
| Paul Hunt |
This thread was discussed between 11/10/2002 and 16/10/2002
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