Quote:
Originally Posted by Mike S.
I wonder why the S62 needs such a specialized additive package? My owner's manual tells me to use an oil with an API rating of "SH" or higher. Mobil 1 0W-40 is "SM" currently. It meets BMW LL01 as well. We can debate the owner's manual info all day long.
I've seen lots of "I heard this, or that guy said that" in this thread. So until we are able to tear down two motors, one run on TWS and one not and compare them, I don't know that we'll get anywhere.
Our engines aren't made out of any special, exotic materials or space-age polymers.
All in my opinion, of course. I could be wrong.
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To be honest i think there is a lot of misunderstanding of how oil actually works. Most people would dismiss 0w-60 because they say its too thin. Sadly that is just not how oil works, a "0" oil will decrease wear and improve lubrication of any engine whilst cold, no matter what engine it is. It will allow the oil to build up pressure quicker and provide the hydro-bearings with fluid much quicker than a "10" or higher oil will (when cold).
Now given that something like 90% or engine wear happens when the eingine is cold, there are obvious benefits to be had here by using a "thin" oil.
when the engine is hot, that is a slightly different story. Once an engine is warm, all the parts that have fluid bearings (crank, big ends, cam shafts etc) run with 0 wear, (as there is no surface to surfacte contact whatsoever). This is not debateable, this is fact, its how engines and bearings are designed.
Now this changes for things like the piston ring´s, which slide across the alusil (low friction) surface, under extreme conditions.
What is important to realise is that people who get broken crank shafts, con rods etc and blame the oil, are simply looking in the wrong place.
DANGER PRESUMPTION COMING UP: I assume that the reason (as far as anyone has thought about it) for the "Oil issues" that are discussed here, is that people think there is not enough lubrication provided by a thinner oil than a thicker oil.
This is not true in the case of any of the main bearings, you will never get metal to metal contact unless you stop the oil supply.
With the Pistons and rings / liners you have a different situation. what should raise a few flags in people minds is the fact that the same oil is reccomended for the S14, S32 S38 etc, and S62 engines. The old cast iron blocks and liners have a very different oil requirement than the new Alu- block and liners. Aluminium/alusil and aluminium /cast iron have completely different friction coefficients and thermal expansion characteristics.
Another thing to bear in mind with the S62 is that it is basically the engine out of the 740 and 540, so do these cars require TWS too?
Ok rant over
What i think is much more important than arguing about specific oil types, is that you use a fully synthetic oil rather than a mineral oil, viscosity is not as important as lubrication, and all synthetics are leagues ahead of mineral based oils.
Also I another thing i think that is quite important that noone ever mentions is are the conditions the car is run under. If you live in germany you will be running your M5 somwhere between -18 to +25 -30 degrees celsius. If you live SOCAL or Nevada you will be running your car in (maybe) +10 to maybe +50 degrees, you will need a different oil for that application.
as an afterthought, this post is purely subjective just as all the other oil posts i have seen on this website, and as we all know, opinions are like a certain part of the anatomy, everyone has one.
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