Oil questions, old Mercedes engine

[Hypergalaxy]

I've read through all of this, and i am starting to get a grasp of what you are saying. Going from what you said at the beginning of this thread, the manufacturer states that you can essentially use any oil under the moon within reason that has the API spec, considering current weather conditions. But that is not answering your questions. 1: There is no merit in seeking SPECIFIC precursor specifications to 229.5, as most, if not all of the oils that have this spec are backwards compatible. It would be the same analogy as how dexron VI is backwards compatible to dexron III and II in most transmissions. 2: You could try your hands with 0w30 and having the "same" properties, but it would be on the thinner end of the spec. Now, you have to remember that there is always some room in that spec 229.5, and since every manufacturer has different formulas in base oils, type of additive packages, and overall manufacturing, some may lean thicker end vs thinner end. However, with modern oil being so good and being made the way it is, it would essentially offer the same protection and give some gains in power and fuel economy. 3:This goes back to what i said at the end of number 2. There would be no discernible difference as long as the oil has the api spec. However, using such a thick winter weight will affect cold start wear, which accounts for 75% of total wear, due to most of that oil going to the bypass because of oil pressure on startup. That being said, you have to account for most european spec oils having to deal with an extended duration OCI, and being so, manufacturers will specifically formulate their oils with higher quality base stock, additive packages, and with that, more testing to make sure it meets the stringent specification. This in turn gets reflected back on the final price. Anyone who reads this and finds mistakes, errors, and things of note, please do not hesitate to reply. I welcome any feedback! Thanks for reading!

 

[kschachn]

Your point #2 and #3 are not correct. Just because an oil has a better winter rating does not mean the operating viscosity is also lower. The old green Castrol 0W-30 was thicker than any other 30-grade oil. Again, as long as the approval is met the HTHS (and MOFT) will provide the "protection". And 75% of wear does not occur at startup, this is an incorrect statement that is often repeated. Besides, even if it did the reason would not be too thick of oil it would be because it is too thin (but this will never happen at initial starup). Unless the temperature is below -35F (or even colder) then an oil with a 5W winter rating will pump just the same as one with a 0W rating. If the system is in bypass with the 5W rated oil then it will also be in bypass with the 0W rated oil. Both will be massively thick, both will be far thicker than what is optimal for operation. At extremely low temperatures the 0W oil is guaranteed to not gel in the vicinity of the oil pickup tube, that is the primary difference. The bottom line is use an oil that carries the proper approval, and unless you are starting at extremely low temperatures ignore the winter rating as it will be meaningless.

 

[Hypergalaxy]

I see. Thanks for the clarification on initial startup wear