Looking for some thoughts about motor oil, my new motor has logged 3000 miles with 3 oil changes, the 1st oil had the break in additive,changed it at 800 miles, the 2nd at 2000, and just now at 3000, I have used striat wt. 30 Shell Rola T the fist 2 and now put 20-50 in. My question is should I stick with the Shell Rola T or switch to a synthetic oil like Mobile one for the next oil change?

I'd stick to the viscosity recommendations from the engine builder, probably 10W40 or 15W40; 20W50 isn't necessary, and not recommended. Rotella T is fine, but overkill; however, its ready availability makes it a good choice.

Yea I think your right Rusty,Rotella T is cheap enough at Sam's Club,and I don't think I will get the milage out of the synthetic to warrant the extra expense.

My 5.9 Cummins has 110,000 miles and doesn't use a drop of oil between changes. I stuck with Rotella 15W-40 even though I have used AMSOIL for years in all of my engines. I thought it was prudent to stay with what is working.

With an engine like these in our coaches I think cost is the last thing to consider and that you should stick with what you start with or what was being used when you bought the unit. Oil is changed based on at least two parameters--time and mileage. Even if you only drive a few miles each year it will behoove you to change the oil once every 12 months. If you are high miles then you will have to change it more often. Oil is cheap--wear is expensive.