Engine oil switch`

I've been using Rotella 15w 40 oil in my 2005 duramax that has 104,000 miles on it and we're planning a long 4 month 8000 mile trip. I'm thinking about changing to Rotella synthetic oil but they don't have it in 15w 40. Is anyone with a duramax using the Rotella synthetic oil? What weight? Thanks for your help.

Why switch, especially if you've ran dino oil this long?


Earl

This will be our first long trip which will be around 8000 miles and I'm hoping to get improved fuel mileage and added engine protection since these will be hard miles. If I do switch to the synthetic I plan on staying with it, it's not just for the trip but I figured it was a good time to make the switch if I'm going to do it.

I've been running amsoil in mine since new after 10,000 mile break'in I change my oil every 20 to 25 thousand miles haven't had any troubles 160,000 miles on the truck now. I might burn a quart of oil between changes at the most but it depends on how much towing I've done. I use the AME 15W-40 synthetic heavy-duty diesel oil and love it.

I use Royal Purple 15W-40. I pick it up at O'Reilleys in 1 gallon containers. I use synthetic in everything, truck, car, tractor, generators. Make sure that you use a good filter like NAPA gold or WIX. I would also suggest that you switch to synthetic before you go and get a filter/oil change again before you leave in case you have any gunk in your engine.

I'll probably switch to the Amsoil since they have the 15w 40.
Thanks guys.
Bill