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MG Midget and Sprite Technical - Oil for a higher mileage engine

I know there are certain individuals on this BBS who take an almost fanatical interest in lubricants so I hope to benefit from such knowledge. The question is simple enough, 'though the answer may not be so.

The car in question (non-MG) specifies a 5W-40 ACEA C3. It's due an oil change, but at nearly 90,000 miles should I now be looking for a slightly thicker oil? And if so what then might be a suitable grade?

Short answer - no.

German engineering and all that, they know their how to make their figures!

Nigel Atkins

And Italian engineering? It just seems to me that at 90,000 miles the clearances will have all opened up so what was accurately specified for a new engine may no longer be ideal.
Just wondering.

Italian, 90k, surely they'll want the engine back to inspect it, where did it go right.

As you know I'm not an engineer or oil technician, I'm sure you would pick up any signs that further attention was required but for precaution you could just continue thorough, regular oil and filter changes, with a reasonable quality oil of the same weight, and other engine servicing and maintenance to see many more tens of thousands being added.

The mileage number is not a direct relation to wear as there are many variables. You could even buy testing kits to see when you need to change your oil to be a step ahead (or behind).

Relevant and matching experience can count a lot so if you can find what the owner of the same engine/vehicle that has done two or three times as much mileage discovered for oil use.

Course, you could look for a thicker version of the 5W-40 ACEA C3 than you are currently using. :)

Or not worry about it.

Nigel Atkins

My modern with 150000 miles on it still runs the silly thin original spec oil.
If it does not leak, use or rattle why bother

I think that modern engines have moved towards using these thinner oils, partly because synthetics have good characteristics, but largely as the lighter oils improve the performance and especially the fuel consumption figures. This is the prime reason as it enhances their car sales and engine longevity isn't really high on the list in a throw away society.

Use of thin oils is only made possible because modern engines can be manufactured to finer bearing tolerances than in earlier generations. So I was thinking that as an engine wears the thin oil originally specified for good fuel economy, may no longer be ideal.

And I don't think that waiting until one can hear the bearings grumble is much of a solution as by then using a thicker oil would at best be to mask its final death rattle.

Yes, but how do you know at what point you need to change, are you going to strip the engine down and have materials testing.

If you view the use of 'modern' and/or 'synthetic' oils as only to get (the already unrealistic) mpg and emissions figures (and what about the poor cats) you forget better oils will protect more and for longer thus reducing wear. So if you use a good quality oil of whatever marketing description and make timely thorough changes of the oil and filter then you will be delaying any need to alter the weight grade if that helps. Remember the grades are in a range, the quality of the oils do vary and the additive packages of the oils vary. You could get a thicker and/or better protecting oil within 5W-40 ACEA C3.

I'm with you I'm all for prevention - and I want it to be very easy and not involve me in much work and certainly not get my hands too dirty - but others would suggest it's all snake-oil marketing and you're wasting your money and time as all oils are basically the same, which to a degree is right. In fact it's all about the degrees of impact and variation and what's worth the sweat or not, to one person to another.

Nigel Atkins

A lot will depend on how the car has been driven. 90k miles mainly on the motorway will produce a lot less wear than 90k around town, up and down the gearbox, as the engine will have a lot less running hours and less stress.

Iíve had several moderns which have done well over 100k in a short time with no engine wear or oil consumption issues.
Dave O'Neill 2

Thanks Nigel. That is an excellent link to the KEW Engineering pages. Exactly what is needed for a wet Sunday morning's read! I already feel understand a little better what the numbers mean.🙂
And as a quickly chosen quote:

[Modern cars are now designed to run on 10W30 or even 0W30. This is partly due to tighter clearances in the machining processes now used, but also to reduce fuel consumption even further and meet the ever tightening Euro specifications on emissions. Owing to the use of synthetics now, the 0W30 oils do not necessarily result in more wear as the film strength of synthetics is superior to mineral oils.]

Dave, it's a 2 owner car. As far as I understand the first owner was doing high mileage longer journeys. It doesn't appear to be burning oil - at least there's no apparent smoking and plugs remain clean. Difficult to be sure though as it is leaking oil. lt's a fiat and their steel sumps rust and go porous, which is why the oil change now as I have a new sump to fit.

The car is a cheapy for local shopping so probably now runs much of its time not properly warmed up. So I probably need to stay with a low W range oil 5W -

I thought you'd probably already seen that link previously, usually put along with a balance link to Paul Hunt's views which relate to classic car oil and are generally opposite to mine and Mr KEW Engineering (who's name I've forgot) but I suppose the link(s) may not have been relevant to your interests at those times.

As with little used classics, because of the low mileage runs, shoppers have even more need of a better oil to protect them. The better oils will have better VII and friction modifiers that will help the oil better protect over the temperature range low and high.

But of course better oils generally cost more and synthetic is more of a marketing term than description. The better synthetic oils will have more synthetic in them, see -

"Can a Mineral Oil be called Synthetic?
The answer is yes. With the advances in refining of crude oils, a process of hydrogen cracking is used to ensure low levels of Sulphur, Aromatics and improved levels of saturated bonds. The argument that was put forward and won in the North American market is that this type of mineral base oil is effectively similar to a synthetic oil in performance terms so in effect the marketing department can legally use the term synthetic (a very emotive term) for Group III base oils."

If you believe you can trust what a technician/employee of an oil blender tells you then contact some to see what they recommend. I found Millers (a UK company) to be easy to deal with for (email) enquiries -

I don't know if the information varies but the presentation seems more up to date on the newer KEW Engineering site (remember it's still one person's opinion, an MGB owner IIRC). -
Nigel Atkins

Quite right Nigel. I rarely follow links posted unless I have a current need for the inormation. Life is far too short for that! And I am not good with the archive searches so it all wafts away on the tides of time.

I accept the advice (yours and others) of "buy the best quality you can afford" but have yet to work out how one identifies best quality if not by the oil grade codes. As you say, a specific code covers a range, but not how to identify quality other than by heresay?

ETA: - the other side of the coin.

It's a cheap shopper, why bother. As it does such low milage the next time the oil will need changing ('pub wisdom') is a long way off and as it's only a shopper put in what you see on special offer and cheapest.

Counter of course is if the oil isn't going to get changed often it needs better, more effective and longer last oil at changes.

If this is the last change of oil it is ever likely to see then again you could put up both arguments for good or cheapest oil.

Boils down to your oil belief.
Nigel Atkins

I run of of time on my edit after your post , so another post -

Guy, the links will help with information to help you with your decision or I've got other stuff too, on both sides of the debate, if you want it (aaaawl no, he cries). :)

Basically there is a price to benefit diminishing returns to the cost of the oil but oil cost is low compared to engine repairs. Oils are relatively a low price item so a 100% price increase is 100% of something low - I'm sure you remember maths lessons - percentage of what.
Nigel Atkins

My opinion--
Why run thicker oil in an older engine when if there is a bit of wear ,you need the lube to get there quick at startup so the thinner oil is the go
my daily hack has well over 300,000 on it now and no sign of any problems and it's been on 0w30 longlife all it's life,15,000klm intervals, except one service when i poked 0w40 in it by mistake and couldn't work out why it wouldn't spool up properly from a standstill
William Revit

As William said thiner oil lubes quicker on startup.
I think thicker oil might even damage a modern engine.
It is designed with thinner oil in mind so using thicker oil might lead to the oil not getting where it needs to (or less quick)

just to add a bit to what Willy's put, the viscosity of the oil and additive package overall rather than just the number range has helped and (IIRC) a genuine in spec 0W will be a good oil to pass the 0W test.
Nigel Atkins

The point is though, that if the bearing clearances have worn, then it's no longer as designed and therefore the original oil specification may not be what is required.

As I understand it, the first number specification related to the oil viscosity cold, at start up. Agreed you certainly don't want to have bearings starved of oil at start up so I wouldn't want to go for a higher number there than the specified 5W. Thin oil is definitely better than no oil!

The handbook lists 5W-40 or alternatively 5W-30 may be used in colder climates. It doesn't define what it means by colder climates except being Italian, I guess that would include the UK. But reading those KEW pages this isn't actually any thicker oil, it is just that it doesn't maintain that viscosity as well at higher temperatures than a 5W-40 that might be preferred when driven by an Italian on a hot Tuscan afternoon.

don't forget 30 and 40 are ranges, 39 is close to 41 but 31 is a lot further away from 49. See the chart below to compare (if the companies use the same measures and remember some will be more stable and remain so longer than others).

Does the car have a Diesel Particulate Filter (DPFs) and Three Way Catalyst (TWC) to worry the ACEA C3 rating?

I thought cars with (some?) DPFs need blow out runs to clear them to help prevent expensive replacements and MoT failure.

"What causes a diesel particulate filter blockage?
Short journeys at low speeds are the prime cause of blocked diesel particulate filters."
"Other things that are bad for DPFs include poor servicing. A diesel particulate filter on a poorly serviced car may fail sooner than a well maintained one, generally, they should last for at least 100,000 miles.

Itís important you use the right type of oil as well Ė some oils contain additives that can actually block filters."

Modern diesels, especially Aldis for some reason, seem to me to put out more sh*t than even old lorries like with petrol engines superficial measures and filters have been added but don't resolve the problems in the base ancient technologies.
Nigel Atkins

What makes you think it's a diesel?
It's Italian!
- ok, I know some Italian cars have diesel engines but it's not what they are best known for!

Well if you don't give the information one has to guess, lots of Italian cars are diesel, and with you concerned about C3 rating and it being used as a shopper I swayed toward diesel, with petrol you can worry less.

And for the sake of asking what make, model, colour and registration is the car. :)

AFAIK Italian cars are known for rust, poor electrics, long arms and short legs and from my experience best avoided. ;)
Nigel Atkins

Not answering your question but my modern(ish) is on 300K+ with oil changes every 20K via suction extractor, still runs fine. I conclude that today's oil is fantastically good stuff and not worth worrying about!

I think that's true Adrian.
The only reason it arose is that with a porous sump that needs replacing, l need to be doing an oil change so the first thing is to buy the oil, but should l go for original specification or a slightly heavier option.

In passing the other thing of note is the capacity which at a meagre 2.6 litres including the filter, is little enough to mean it must all work that bit harder!

a couple of professional working mechanical/engineering mates swear by Castrol Magnatec, one in his everyday Spridget (avert your eyes, 10w-40 too! BL specified for the donor A-series Maestro van engine, which is on a Webber and goes very well) and the other mate (I have two!) for his Ford Zetec engined Westfield.

So how about Castrol Magnatec 5W-40 C3 Fully Synthetic Car Engine Oil - 4 Litres, that way they a couple of litres for top up or next service.

Or if you're doing the labour unpaid or want belt, braces, bit of string and chewing gum protection - Millers Oils NANODRIVE EE LongLife 5w-40 Full Synthetic.

Nigel Atkins

Yes Nigel, that's what I bought yesterday, using a weekend discount plus a £5 off code from eBay. Brought it down to just over £24.

A mate who works in engine design and development mentioned that the oils are so good now a lot of the manufacturers are not hardening the crankshafts as they don't need to to achieve the design life.
David Billington

BP or Brighouse?
Nigel Atkins

Do you get Castrol Edge there-----
It's got me, I have to know, what car is it
Guy, just out of interest

Nigel, earlier you mentioned a chaffy Audi diesel, that's exactly what my golf diesel was like with the 40 oil in it, you'd stick your foot in it and it'd smoke till the turbo wound up, but with 30 it spins up as clear-no smoke at all and pulls hard right from standstill
William Revit

you change the oil on yours full stop, the reason I notice Aldis, apart from them taking over the BMW 'driver' mantle, is that a neighbour has one. He's the next generation down and of his age group, very decent chap in himself. He's mates in the car trade. His Aldi is all black, with what looks like to me illegally dark side windows and a darkened rear (yellow) number plate. Darkened rear lights and rear plates are (were?) fashion here, the plates as I think some think it will help against against ANPR and speed cameras.

All the darkening is ironic on my young neighbour's car as the one and only time I have been behind his car I don't think I've ever seem denser black smoke come from the exhaust of any vehicle in my life. When I told him about this and suggested he needed to give it a blow out he reminded me that his part-weekly commute to work 30 miles each way, I suggested dropping a few gears rather than going faster. :)

Now I might be wrong but I guess the oil doesn't get changed regularly or his car serviced, if ever, based on other dealings with his previous cars and the loan cars he sometimes gets when cosmetics are done on his car by his mate. And how he, or his mate, get girlfriends with the stupid signs (sayings) they put on their cars surprises me (but he does) must be their culture of disrespect towards women.

The only other vehicle I've seen produce so much smoke was another Aldi hence they stand out to me for this.
Nigel Atkins


Taliking of smoke, Derby council were checking taxis at the weekend, with the assistance of Derbys roads policing unit.

This was one of their victims.

Dave O'Neill 2

"Aldis" smoke might also be due to some "budding geniuses" looking for "more performance":
Remove/shut of EGR valves
Remove of DPFs

Some of those are also, don't get me wrong, consequence of non-reliable systems out of the factory in the first place...
CH Hamon

if only it did include a small puff of grey like that, seriously both Aldis seemed twice as bad as that, possibly three times.

I'm beginning to wonder if my neighbour's car was perhaps white when it first arrived here.

I do not know what might have been changed on the car but I doubt if my neighbour has done anything to it, particularly servicing.
Nigel Atkins

This thread was discussed between 21/09/2019 and 24/09/2019

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