I have a 05 duramax that I run synthertic motor oil in (no problems doing so) since I had 5000 km's on it (now has 35 000 km's). I was wondering if any one knows if there is a any one that has put synthetic oil's thru-out the whole chassi (differentials, transfercase and transmition)?.

 

Good and Yes, I have done it. I am pleased.

 

I have run synthetics throughout my truck for three years. No problems at all. I get 19 MPG in my 2003 Silverado (Duramax). A little more pricey but I think well worth it.

 

You guys might find this oil information worth while. I use Castrol Syntex in my tractors and Mobile 1 in my Vette. This guy gives some interesting facts on what wieght of oil to use and why.
http://forums.corvetteforum.com/show....php?t=1791708