Important Notice: Our web hosting provider recently started charging us for additional visits, which was unexpected. In response, we're seeking donations. Depending on the situation, we may explore different monetization options for our Community and Expert Contributors. It's crucial to provide more returns for their expertise and offer more Expert Validated Answers or AI Validated Answers. Learn more about our hosting issue here.

Why do some engine manufacturers specify SAE 30 oils while others want 15W-40?

0
Posted

Why do some engine manufacturers specify SAE 30 oils while others want 15W-40?

0

Almost all heavy duty diesel engine makers now favour SAE 15W-40 engine oils. The benefit is generally a lower oil consumption plus lower wear partly as the oil circulates faster after a cold start and partly as a multi-grade can also generate thicker oil films in bearings and between rings and liners than a straight 30 or even a straight 40. There is no engineering reason why a 15W-40 multi-grade using the current best technologies would not perform at least as well as an SAE 30 mono-grade in almost any engine. Monograde oils are, however, still preferred for some older 2-stroke diesel engines.

Related Questions

Thanksgiving questions

*Sadly, we had to bring back ads too. Hopefully more targeted.