10w30 for ISX?

10w30 is kinda strange. I would think that might be good if you spend all your time in the cold. I've never run anything besides 15w40 in over 30 years of driving. Always liked delvac. The engine makers all claim you can do 40k between changes, but I always did 15. That's about where it would be about ready to add some

 

What does your owners manual say about type of oil and change intervals?

 

10w30 for Heavy Duty Diesels is synthetic oil which, even though people might think 15w40 conventional oil would offer better protection, the lighter Synthetic offers equal or better, plus even though it's thinner it offers a increase in fuel economy as there is less rotational drag on the engine vs. conventional oil.

 

So your saying just the fact that it's 10w30 for diesel makes it a synthetic oil?

 

It's actually a synthetic blend.

 

Kenworth actually recommends the 10w30 oil in the Paccar MX and they are saying it can go 60000 miles between oil changes. As tnevin said, they also say it offers maximum protection and better fuel economy.

 

Did you get your truck yet Hegemeister?

 

No. It's waiting for me at the dealership. I'll be picking it up on Nov. 6th. Counting the days. Don't want to hijack the thread. Thanks.