I think it's more important to think about what the truck will be doing. I don't disagree with the engineers, but the trucks aren't new anymore either...

The engineers didn't have towing a 3000# trailer up Roger's Pass in mind when they built my truck. But I had it in mind when I bought it. They also didn't have Moab in mind. But I did. <img src="/forums/images/graemlins/wink.gif" alt="" /> Stock tires were 31s, so I've already changed shift parameters, RPM range, etc, so the conditions the truck was built for are gone out the window. The manual probably also doesn't spec synthetic oil, but that doesn't mean it's a bad idea... You see where I'm going with this?

They are trying to recommend an oil that is good under most average conditions, most of the time. And I'd agree with that. But if you want to get specific with your conditions and your times, then I see nothing wrong with switching it up to suit...

My 2 cents is not equal to Mitsu engineer's design parameters, obviously...

<img src="/forums/images/graemlins/lol.gif" alt="" />