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MG MGB Technical - High Mileage Oils

Is it worth on using the Castrol High Mileage (for more mature engine) oils based on these specs

http://home.comcast.net/~dsmphotos/cgtx.jpg

http://home.comcast.net/~dsmphotos/himile.jpg

Paul
Paul

I use Mobil one synthetic 15:50....perfect oil...change every 5K and your motor will last forever.
P J KELLY

Hello Paul,


Well I do believe that it is snake oil this kind of product as extra pennies you pay you do not get a real plus-value...

And Mr Kelly, I have always heard on that BBS that full synthetic oil will make B oil seal to desintegrate. I am happy to see a positive opinion on that matter...

Cheers,
Jean Guy Catford

Thee are two main things you're probably looking for in the mototr oil. First, the faster it flows at startup, the less wear there is (some advocate cranking for a while to build some oil pressure). Second is that it is sufficiently resistant to heat to retain lubricating capacity at high temps. In a 'seasoned' engine the additional viscosity might also help to reduce the amount burned as a result of rings/guides.

Modern multi-weight oils do better at this than the old single grades (just as a matter of definition), and the real benefit of the synthetics is the range achievable (0w-40, 5w-50, etc.) As the price of decent regular oil increases towards $2/qt, the synthetics start to look a lot less pricey as an upgrade.

Steve
Steve Aichele

Jean...if synthetic does cause a leaky seal or gasket, it can often be slowed or stopped altogether using Lucas Oil Stabilizer. I do agree however that you need to be very careful introducing synthetic to an old engine...it can be really searching!
P J KELLY

Jean,

The risk in changing to a Synth in a mature engine is it cleans engine of gunk and the recommendation is short oil and filter changes until cleaning process has finished, and although seals may initially leak this should rectify itself. Still a risk and unless planning to utilise benefits of synthetic maybe not worth it.

Paul
Paul

I am a sceptic, but would be interested to hear if anyone knows of independent studies to support the worth of synthetics, or "Classic" oils that command a premium price over standard oil. I stopped using synthetics (in a Saab turbo) after talking to a QA technician in the R&D dept of the last company I worked for. She had just moved from one of the big oil companies and had been responsible for analysing the performance data of their own synthetic oils. Her verdict was "99% marketing, 1% science".
Her recommendation was to use a branded oil, for the additives, and to change it regularly. I heard the same advice from enough knowledgable people for it to sink in; I change the oil at 4000 mile intervals using good basic 20w/50.
The temptation I felt with synthetics was to delay oil changes to offset the cost, especially when goaded by friends who cite 24,000 mile service intervals on modern engines.
Steve Postins

Some number of years ago I worked as the supply contracts manager for a mining company and one of the products under my "responsibilty area" was fuels oils and lubricants.

Having a B at the time I also asked this very same question and was given about the same answer as Steve posted above albeit phrased in less delicate and tactful terminology!

This was from the engineers not the sales people and the company was and still is one of the main players with a station on just about every corner.

Simply put: It's your dollars so spend them as you will but in my experience it is not a good idea to take advice from anyone who will profit from the advice they are giving you.

If they are able to make a buck from the product it is hardly surprising they will sing the praises.

My 2 c worth.

Cheers , Pete.
P Thomas

Interesting thread regarding synthetic and standard oil. I have wondered if Lucas oil stabilizer (very good stuff) is compatable with the synthetic oils.
Or is Lucas a synthetic itself?
Things that make you say hummm?

Dan H.
Dan Hanson

Technology always marches on. At one time detergent oils were the new kid on the block, later it was multi grade oils. Over the years, advances in polymer technology have drastically improved the lubricating qualities of our oils and extended their service lives as well. When major manufacturers begin to sell oils especially blended for different types, ages, or usages of engines, to me it just stands to reason that this is the next direction that research has taken us. Why should one version of an oil be ideal for all applications? Now if were another "mechanic in a can" being flogged via TV infomercials, I'd probably be a bit more skeptical--to the point I would not watch, much less purchase. Remember, newer cars are built to a different tolerance level than our venerable crates, and so what works in my 2004 is obvously not the best fit for a twenty five to forty year old car, built using what really amounts to pre-war technology.
R. L Carleen

I bought my '70 BGT this summer and when it needed its first top-up put in synthetic Shell Helix plus 20/40W. It had an engine rebuild in 2000, but reading the above I'm wondering if this may be related to why I'm getting misfiring and an oily end to number 3 plug! Should I just go back to classic 20/50W now and hope for the best?
Tim Jackson

One of the big selling points for synthetic oil is its longevity. However, I'm not convinced that synthetic oil is going to decrease the dirt I suck in through the air cleaner, or the combustion residue that blows past my piston rings. All of the grime which doesn't get trapped by the oil filter is still floating around in my oil passages. For that reason I would want to change oil on the same schedule, synthetic or not. So for that reason, I wouldn't see a benefit to synthetic oil.

Now, if the synthetic were made from a resource more renewable than petroleum, that would be a good reason for me to switch. What exactly are the raw ingredients for synthetic oil, anyway?
Matt Kulka

Matt

This must be for you- oil you do not have to change!

http://www.synlube.com/viscosit.htm

Some specialist race oils are Castor Oil!

A basic mineral oil has impurities and hence the move to Hydrocracked oil used by Castrol Shell and called Synthetic.

For performance high temp etc esters come into their own, used as a base in oils like Redline and Motul.

Esters are also polar, will be attracted to engine components and will always provide an oil film.

Paul
Paul

Off intended topic but the biggest buck is probably made from mineral and regular oil changes.

A view of
SYNTHETICS vs MINERALS

Oil is the lifeblood of your vehicle's engine. For decades conventional petroleum
oils have been providing adequate protection for all of our vehicles.

The key word here is adequate. Petroleum oils, for the most part, have done an adequate job of protecting our engines from break down. If you change it often enough, you can be relatively sure that your car will last 100,000 to 150,000 miles without a serious engine problem - maybe even longer.

The real question is, why settle for adequate when something better has been available for
about 30 years?

Today's engines are built for better performance, and, although petroleum oils are designed for better protection and performance today than they were 10 or 20 years ago, there is only so much that can be done. Today's engines need high performance lubricants, and the only true ones available are synthetics.

Conventional petroleum oils are insufficient for use in today's vehicles primarily because they are manufactured from a refined substance, contain paraffins (wax), sulfur, nitrogen, oxygen, water, salts and certain metals. All of these contaminants must be refined out of the basestock in order for it to be useful for use within a lubricant.

Unfortunately, no refining process is perfect. Impurities will always remain when any refining process is done. It simply isn't economical to continue to refine the oil again and again to remove more impurities. If this was done, petroleum oils would cost as much as synthetic oils do.

There are many components of petroleum oil basestocks which are completely unnecessary for protecting your engine. They do absolutely nothing to enhance the lubrication properties of the oil. In fact, most of these contaminants are actually harmful to your oil and your engine.

Some of the chemicals in conventional petroleum lubricants break down at temperatures well within the normal operating temperature range of your engine. Others are prone to break down in these relatively mild temperatures only if oxygen is present. But, this is invariably the case anyway, especially since oxygen is one of the contaminants within petroleum basestocks.

These thermally and oxidatively unstable contaminants do absolutely nothing to aid in the lubrication process. They are only present in conventional petroleum oils because removing them would be impossible or excessively expensive.

When thermal or oxidative break down of petroleum oil occurs, it leaves engine components coated with varnish, deposits and sludge. In addition, the lubricant which is left is thick, hard to pump and maintains little heat transfer ability.

In addition, petroleum oils contain paraffins which cause dramatic oil thickening in cold temperatures. Even with the addition of pour point depressant additives, most petroleum oils will begin to thicken at temperatures 10 to 40 degrees warmer than synthetic oils.

As a result, petroleum lubricants will not readily circulate through your engine's oil system during cold weather. This may leave engine parts unprotected for minutes after startup. Obviously, significant wear can occur during this time frame.

Even when all conditions are perfect for conventional oils to do their job, they fall far short of synthetic oils. Part of the problem is that (because of their refined nature) petroleum oils are composed of molecules which vary greatly in size. As the oil flows through your vehicle's lubrication system, the small, light molecules tend to flow in the center of the oil stream while the large, heavy ones adhere to metal surfaces where they create a barrier against heat movement from the component to the oil stream. In effect, the large, heavy molecules work like a blanket around hot components.

There is also another effect of the non-uniformity of petroleum oil molecules which reduces their effectiveness. Uniformly smooth molecules slip over one another with relative ease. This is not the case with molecules of differing size.
Theoretically, it might be somewhat similar to putting one layer of marbles on top of another (if this could easily be done). If the marbles were all of the same size, they would move over one another fairly easily. However, if they were all of differing sizes, the result would be much less efficient.

In the case of petroleum oils this inefficiency leads, ironically, to added friction in the system (the very thing that lubricants are supposed to reduce). Hence, petroleum oils are only marginally capable of controlling heat in your engine. Considering that motor oil does nearly 50% of the cooling of your engine, that's not a good thing. But,

This being said, petroleum oils are “adequate” for the purpose of protecting your engine, if you don't mind a shorter vehicle lifespan, inconvenient oil changes, or decreased engine
performance. Under normal circumstances, most vehicles lubricated with petroleum oil should run satisfactorily for 100,000 to 150,000 miles without serious incidence.

If you like the hassle of changing your oil regularly, and you are only looking for marginal
performance for the next 100,000 miles or so, petroleum oils are definitely the way to go.

Assuming that you don't relish the idea of changing your oil every 2,000 miles or and are looking to keep your “pride and joy” in tip-top condition then these are the main areas where synthetic oils surpass their petroleum counterparts.

Oil drains can be extended
Vehicle life can be extended
Costly repairs can be reduced
Fuel mileage can be improved
Performance can be improved

Synthetic basestock molecules are pure and of uniform size. This is because synthetic basestocks are designed from the ground up with the sole purpose of protecting your engine. Nothing is added if it does not significantly contribute to the lubricating ability of the oil.
In addition, in top-quality synthetics, no component is added which might be contaminated with any substance that might lessen the lubricating qualities of the oil. In other words, manufacturers of these premium synthetics implement very strict quality control measures to insure no contamination.

Not only that, synthetic basestocks are designed so that the molecules are of uniform size and weight. In addition, synthetic basestock molecules are short-chain molecules which are much more stable than the long-chain molecules that petroleum basestocks are made of. This significantly adds to the lubricating qualities and stability of the oil.

EXTENDED OIL DRAINS
Stable Basestocks
Synthetic oils are designed from pure, uniform synthetic basestocks, they contain no contaminants or unstable molecules which are prone to thermal and oxidative break down.
Moreover, because of their uniform molecular structure, synthetic lubricants operate with less internal and external friction than petroleum oils which have the non-uniform molecular structure. The result is better heat control, and less heat means less stress to the lubricant.

Higher Percentage of Basestock
Synthetic oils contain a higher percentage of lubricant basestock than petroleum oils do.
This is because multi-viscosity oils need a great deal of pour point depressant and viscosity modifying additives in order to be sold as multi-viscosity oils.
Synthetic oils, require very little in the way of pour point depressants and viscosity
modifiers. Therefore, synthetic oils can contain a higher percentage of basestock, which actually does most of the lubricating anyway. More basestock leads to longer motor oil life.

Additives Used Up More Slowly
Petroleum basestocks are much more prone to oxidation than synthetic oils, oxidation inhibitors are needed in greater supply and are used up very quickly. Synthetic oils do oxidize, but at a much slower rate therefore, oxidation inhibiting additives are used up much more slowly.
Synthetic oils provide for better ring seal than petroleum oils do. This minimizes blow-by and reduces contamination by combustion by-products. As a result, corrosion inhibiting additives have less work to do and will last much longer than within a petroleum oil.

Excellent Heat Tolerance
Synthetics are simply more tolerant to extreme heat than petroleum oils are. When heat builds up within an engine, petroleum oils quickly begin to burn off. They volatize. In other words, the lighter molecules within petroleum oils turn to gas and what's left are the large petroleum oil molecules that are harder to pump.
Synthetics are resistant to this burn-off. They will tolerate much higher engine temperatures.

EXTENDED VEHICLE LIFE WITH FEWER REPAIRS
Heat Reduction
More often than not, vehicle life is determined by engine life. One of the major factors affecting engine life is component wear and/or failure, which is often the result of high temperature operation. The uniformly smooth molecular structure of synthetic oils gives them a much lower coefficient of friction (they slip more easily over one another causing less friction) than petroleum oils.
Less friction, of course, means less heat in the system. And, since heat is a major contributor to engine component wear and failure, synthetic oils significantly reduce these two detrimental effects.
In addition, because of their uniform molecular structure, synthetic oils do not cause the "blanket effect" which was mentioned earlier. Since each molecule in a synthetic oil is of uniform size, each is equally likely to touch a component surface at any given time, thus moving a certain amount of heat into the oil stream and away from the component. This makes synthetic oils far superior heat transfer agents than conventional petroleum oils.

Greater Film Strength
Petroleum motor oils have very low film strength in comparison to synthetics. The film strength of a lubricant refers to it's ability to maintain a film of lubricant between two objects when extreme pressure and heat are applied.
Synthetic oils will typically have a film strength of 500% to 1000% higher than petroleum oils of comparable viscosity. In fact, believe it or not, even though heavier weight oils typically have higher film strength than lighter weight oils, a 0w30 or 5w-40 weight synthetic oil will likely have higher film strength than a 15w40 or 20w50 petroleum oil.
Thus, even with a lighter weight oil, you can still maintain proper lubricity and reduce the chance of metal to metal contact when using a synthetic oil. Of course, that means that you can use oils that provide far better fuel efficiency and cold weather protection without sacrificing engine protection under high temperature, high load conditions. Obviously, this is a big plus, because you can greatly reduce both cold temperature start-up wear and high temperature/high load engine wear using the same low viscosity oil.

Engine Deposit Reduction
In discussing some of the pitfalls of petroleum oil use, engine cleanliness is certainly an issue. Petroleum oils tend to leave sludge, varnish and deposits behind after thermal and oxidative break down. They're better than they used to be, but it still occurs.
Deposit build-up leads to a significant reduction in engine performance and engine life as well as increasing the number of costly repairs that are necessary. Since synthetic oils have far superior thermal and oxidative stability than petroleum oils, they leave engines virtually varnish, deposit and sludge-free.

Better Cold Temperature Fluidity
Synthetic oils and other lubricants do not contain paraffins or other waxes which dramatically thicken petroleum oils during cold weather. As a result, they tend to flow much better during cold temperature starts and begin lubricating an engine almost immediately. This leads to significant engine wear reduction, and, therefore, longer engine life and fewer costly repairs.

IMPROVED FUEL MILEAGE AND PERFORMANCE
As indicated earlier, synthetic oils, because of their uniform molecular structure, are tremendous friction reducers. Less friction leads to increased fuel economy and improved engine performance.
Any energy released from the combustion process that would normally be lost to friction can now be transferred directly to the wheels, providing movement.
Vehicle acceleration becomes swifter and more powerful while using less fuel in the process.
The uniform molecular structure of synthetic oils has another performance enhancing benefit as well. In a petroleum oil, lighter molecules tend to boil off easily, leaving behind much heavier molecules which are difficult to pump. Certainly, the engine loses more energy pumping these heavy molecules than if it were pumping lighter ones.
Since synthetic oils have more uniform molecules, fewer of these molecules tend to boil off.
More importantly, when they do, the molecules which are left are of the same size and pumpability is not affected.
Paul

Hard enough getting 20 50 weight oil in mineral. I dont think I have ever even seen 20 50 weight in systhetic even in a magazine.
jim

I have owned MGs almost continuously since 1963.

I currently have an MGA 1600 Roadster, an RV8 and a 220 bhp 1973 B GTV8 which I have owned for over 30 years.

All my MGs have oil & filter changes ever 3000 miles, and I have always used 20/50 (almost always Duckhams) - oil pressure has always been good and TBO excellent.

I see no reason to change this regime.
Nigel J S Steward

Horses for courses, gentlemen (and ladies).

In my '62 midget I run mineral oil, with a change once a year, which will amount to very few thousand kilometres. I have just rebuilt the engine, and if it lasts 100,000km, that will most likely mean that it will outlast the earth's supply of crude oil. Never mind the fact that the body around it will have turned to reddish brown powder.

In my '02 TF160, I will continue to use the recommended synthetic oil. Sure I could save a little by running mineral oil, but as a percentage of the costs of owning and running the vehicle, my saving would be irrelevant.

One more point: when our classic MG's were designed (A's, B's, Midgets and earlier cars), oil filters were a lot more basic in design than they are now. Improved filtration does a lot to increase service intervals, it's not just improved oil technology.

James
James Reinhardt

Don't get hung up on finding 20W/50 - the factory also recommended 10W/40 for the same operating temperature range.
Chris at Octarine Services

Given that basic mineral oils of 20W50 use a polymer structure to reduce the thinning of the oil as it warms up, and that these are susceptible to damage and entrapment in finer filters, then there is every chance that after a period of settling, a 20W50 becomes more like a 20W40. With Synthetics the Viscosity Index is naturally high and does not required the use of VI improver additives, so a 10W40 will stay a 10W40.
So putting those facts together, both a Mineral 20W50 and a syn 10W40 should both achieve a 40 grade at operating temperature. And as the weather turns cooler, I know which one I would prefer for a cold start (the 10W rather than the 20W in case you aren't sure!).
More importantly, proper use of the engine (ie. longer runs rather than supermarket runs) will ensure contaminants are burnt off, so, and as James points out, with improved filtration, longer service intervals are the norm. On my 02 MG ZT with V6 2.5L it runs Mobil1 0W40 for the service interval of 12k miles which is approx 6 mths of usually 50+ mile journeys. BMW are offering a 24k mile or two year service interval on their diesels. Part of this is commercially driven to make a vehicle look more attractive through lower running costs, and most cars will tolerate that for the warranty period of 60k miles or 3yrs. The downside is that it has reinforced the belief that modern cars are sealed for life and hence few people check their oil level regularly enough. A recent survey by an independent warranty company has found that 1 in 20 claims result from insufficient attention to oil level checks.

On my rebuilt GT engine, it currently gets regular changes of 20W50 mineral at increasing intervals since the engine went back in 3000 miles ago, and with modern machining methods it should tolerate a 10W40 synt relatively well, but investigation will determine that. However, as Paul pointed out, Grp III hydrocracked mineral oils are less prone to carbonising and tolerate higher temps and are legally deemed a synth in the US. However, a true Grp IV synth is a PolyAlphaOlefin base which can tolerate much higher temps with longer service life (reduced oxidation rate), but it requires an ester base for the additive package. The ester is known to be a highly detergent compound and it is for this reason that components of engines run on Mobil 1 will show up as extremely clean and free from deposits etc. Esters cause seal swell, PAO's cause seal shrinkage, so the two offset each other, and seal leakage shouln't be an issue, unless the seal face is crudded over, in which some weeping will occur as the deposits are lifted.

Based on this, at the very least, Mobil 1 is a good flushing oil between services. If the engine is run for a while with the Mobil 1 and then drained and put back on mineral 20W50 for normal use, this would offset the build-up of deposits. Whether you consider these deposits to be beneficial rather than a negative factor depends on how you view them. Deposits can prevent oil consumption and leaking, but the deposits can also accelerate oil oxidation, and prevent heat dissipation from the surfaces.

With regard to friction losses and fuel economy, I have indeed seen benefits between running a 15W40 and a 0W40, although technically there shouldn't be as both have a similar viscosity at operating temp. However, the molecular structure of synth is far more consistent than a mineral so the fluid friction is less. According to the independent testing, the fluid friction should only have a minimal impact, of less <1%, on economy because of where all the energy is dissipated in an engine. But it is noticeable. Therefore the 2x times cost of Mobil 1 against a cheaper oil is balanced against the confidence I have that my new MG will run happily for 12k miles, rather than needing a 6k service interval every 3 months. As I hope to keep the vehicle for 150k miles or 5yrs, this is important to me along with the best quality fuel available. Apart from the reliability aspects, there are the improvements in performance (or no loss of original performance over time) and the beneficial impact on the environment. Plus, I probably breakeven or just about over using cheaper oils and fuels.

The trouble is is that budget motorists will then choose a cheaper oil and other service items expecting these to last as long as the more expensive oils. This will probably work if the car is owned from new for 60k/3yrs. It is the second owner that suffers, but does the manufacturer or the first owner really care? The environmental issues behind this suggest that increasing the vehicle's useful and reliable service life makes more sense as more pollution is caused making a car than using it for its expected life.

Taking a pragmatic approach, as James pointed out, will determine what works best for each owner, but some of us, as lubrication reliability engineers working in industry, can't help wanting to investigate for the greater good (although no-one has ever defined to me what the greater good is, but it's a good reason to continue!)

Anyway, enough rambling from a sad old geezer too involved in machinery lubrication for a living!

Martin.
Martin ZT

Martin

With regard to M1, it could be that esters are no longer being included and replaced by AN also a synth.

In the US Auto-rx is highly recommended for cleaning and for use with minerals.

In the UK the most readily available Castrol GTX is 15/40, I assume that this is a suitable mineral replacement following Chris's comment re 10W40.

Following Jame's point, the UK appears to be devoid of decent oil filters such as K&N.

Nigel,

My own view is that additive packages have also improved over years with a mineral oil, so there is no real reason to change to more expensive synth unless the benefits would be used. However as Mercedes have recently found out using an under spec oil can cause problems.

Matt,

The origins of Synthetic!

Mobil used an acid derived from coconut oil and built an ester upon it for their Mobil 1 Tri-syn product.

The Germans in WWII found that the oil of castorbeans made a synthetic lubricant, until it oxidized and then turned into crud. What they later discovered was that the castorbean contained a natural ester and glycerine; it was the glycerine that accelerated oxidation. When they separated the castor acid from the glycerine, and then reacted an alcohol with the acid, they came up with one of the first ester lubricants known to man. What they didn't know was that secretly, Standard Oil and Union Carbide were doing the same thing for the Allies and had made various synthetic lubricants before the Germans really needed them

Paul
Paul

In the UK oils recommended for 'high mileage' engines are usually also recommended for 'older' pre-injection engines like the MGB. There are other grades for 'older injection engines' and still more for 'modern engines'. I used GTX for years and never noticed its change from 20W/50 to 15W/50, but a couple of years ago I did notice when it changed to 15W/40 in my V8 -lower hot idle oil pressures - but not in my 4-cylinder. I've now changed to using a basic 20W/50 oil in the V8 which gives better oil pressures and is cheaper than GTX. There didn't seem much point is paying out for GTX for the 4-cylinder and having two cans of oil in the garage for topping-up, so I have changed to the 20W/50 for both, ending an association with GTX for many years, I can remember when it first came out.
Paul Hunt

This thread was discussed between 12/10/2004 and 15/10/2004

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