Interesting article on oils

[Lin]

From this article, one can see that there could be a benefit to using a multigrade oil even in a DD.  However, don't forget to read the part on Drawbacks of Viscosity Improving Additives used in multigrades so you get the whole picture.

http://www.upmpg.com/tech_articles/motoroil_viscosity/index.html

[bevans6]

What they are suggesting, and as far as I know it's actually true, is that Group IV synthetics ("true" synthetics) can meet multi-grade testing standards for cold and warm viscosity without having viscosity improvers.  Which makes them technically single grade/multi grade at the same time.  If they have the ash requirements, resistance to high temperatures, coking up the piston ring resistance, etc, needed for two stroke diesels I don't have a clue.  It is true that multigrades that do have some types of viscosity improves do degrade to their base level which is usually the cold viscosity when the additives degrade, and they are some of the same additives that burn out as ash.  For me this would only be relevant if I had to start the bus engine regularly at cold temps and didn't have access to power to heat the oil.  I don't have that situation, so I don't have to make a decision to run multi-grade oil.

Brian

[Lin]

I found it interesting that a 40wt basically stays 40wt, which is what I would want.  My cars though have multigrade and, although my generator manual recommends 30wt, I have considered multigrades there.