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A good synthetic is cheap ! (archive)

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Posted by Age P on January 22, 2002 at 17:11:25:

In Reply to: Yep....I've been using Mobil 1 too.... posted by Derin on January 22, 2002 at 16:53:38:

Guys I full support the oil debate, synthetic oils are substantially superior to mineral based oils. I use castrol RS 10/60 or mobil 1 15/50. Who cares that the oil is 30 to replace !

Get your head around 7,500 rpm and the number of revolutions that poor little s14 will undertake between oil changes. The sheer film strength and polymer strength far exceed those of mineral based ois. The stability is a significant factor and the tolerance of heat, this is not the overall oil temperature but right at the nose and flank of the cam at high rpm. believe me the oil has a real hard time. I will change my oil with fully synthetic every 3,000 If I spend 30 a year too much who cares ! I adopt the same philosophy with my 911 RS and that takes over 4 cans !!! I have just rebuilt my M3 engine, I bet if the previous owner was as fastidious as me I wouldn't of needed to. Service intervals by the way have come down not only through well designed and well filtered engines, better oils but the need for manufacturers to reduce the 'need' for service intervals from a buyers perspective.
....I've had it in for over 4000 miles. I have no intention of changing my oil every 3000 miles either. I don't 'track' my car I rarely strain things for extented periods. All I'm saying is that that is what was written in that article and I wonder if for most people using their cars 'in the real world' (ie not regular track work) whether the price differential is really worth it?

I don't know what the price difference is in the U.S but here in the UK the cost of the oil for a change using Mobil 1 works out close to $50... just for the oil...the oil using a good Mineral oil is about one third the cost.

Now, if we agree that 3000 mile changes are excessive but say go with the Service Indicator lights which in my experience on BMWs of this vintage seem to 'loose all the greens' around every 6000 miles? ( I know the Service Indicators don't calculate simply on a mileage basis). So we change our Mineral Oil at this frequency at (say)$15 a shot....Will using the equivalent cost in terms of Synthetic (eg Mobil 1 at $45+ a shot) afford us the same degree of protection for 18000 miles? Or will the protection (at $45 a shot) be three times better during the 6000 miles? I suspect neither?

Indeed, what is 3x better protection? How do we measure that? take the engine apart and see if there is 'three times less wear'? I doubt it! we simply assume that "it's a bit better and we're prepared to pay a lot more for it"? I suspect that's actually the truth of it.

Now, I'm not saying there's necessarily anything wrong with "paying a lot more for a little bit better"....if that really is the case but what I'm really questioning is: does that really makes a difference to people like me who rarely drive their cars that hard for extended periods? At the moment I pay the extra.....I'm not sure that I need to?


The fact that it protects longer is significant if a synthetic oil can test better at 15000 miles than a mineral oil at 0 miles which is true in many cases. It is also true that mineral oils can do much much worse on standard tests after 3000 miles than they do when new...maybe you should change your oil every 500 miles?

Synthetic oils score much better on all standard tests than the best mineral oils...friction tests, wear tests, evaporation tests, thermal stability tests, viscosity tests, etc. They do this throughout the life of the oil. I have seen countless articles and data reports, partial and impartial to support these statements.

I've decided that the price difference between mineral oil and Mobil 1 is worth it to me. Redline and Amsoil, while superior to Mobil 1, are quite a bit more expensive and so I'm not stepping up to them.

So, when I say that good synthetic oils 'protect' the engine better, I mean that they flow where they are needed, they stay where their needed (don't evaporate), they reduce friction better while they are there, they hold up to high stress and temperature, and they do it all better than mineral oil and, in general, for well over 3000 miles.


>...It was the article in 'Total BMW'- Feb 2002....right?

They asked someone who regularly works with these cars. His recoomendation was that oil grades of 10W/30 be used and that ordinary Mobil 1 and grades at 0W or 5W were too thin.The suggestion was a good quality mineral oil like Duckhams Hypergrade would be fine.

Whilst it is 'ridiculous' to suggest that engines 'like' something it is also 'misleading' (IMHO) to believe synthetics 'protect' an engine better simply because they are synthetic. The advantage of synthetics ( as I understand it)is that they retain their properties LONGER.

However, if (as most enthusiasts seem to be doing here) one is changing the oil every 3000 miles or so this probably obviates the need to use synthetics.

It is also true that synthetics lead to more leaks by seepage past gaskets as they tend not to be absorbed and therefore do not lead to expansion of the gasket.

The above two should make one question whether it's worth the considerable extra cost of synthetics such as Mobil 1 if one is prepared to change oils frequently?

I think much of the 'oil debate' centres around a lot of 'myth' just in the same way as the old 'myth' of 100K mile cam chain replacement?

Just my 2 cents worth.

To say that an engine "doesn't like" synthetic oil is somewhat ridiculous. Synthetic oil is superior to conventional oil in all respects. Also 15W50 Mobil 1 is not "too thin."

Synthetic oil is much more stable than conventional oil. One on its major benefits is that it works almost as well at 5000 miles as it does when you put it in. The main reason for changing synthetic oil is contamination by combustion blow-by, etc.

The only problem synthetic might cause is when you switch from regular oil to synthetic after some time. You might get oil leaks. This is because conventional oil is soaked up by gaskets which then expand whereas synthetic is not soaked up to the same degree. So, after you switch to synthetic, the gaskets can dry and shrink back down causing leaks. Then, you just have to replace the gasket.

I think the benefits outweigh the risks (leaks). Good synthetic oil protects your engine much better.


Anybody have any views on using Mobil 1 Motorsport in the S14?
I've seen quite a lot of stuff about not using regular Mobil 1 (as it's too thin) but I recently read an article that said S14's don't like synthetic oil of any description.
Anyone like to clarify this for me so I can sell the Mobil 1 Motorsport to my mate with the Cossie if need be.


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