When I first got my truck I changed the oil to 5w-40 Rotella Synthetic oil. The last oil change I put Rotella 15w-40 because WallyWorld didn't have the 5w-40. Last night I changed the oil again and put 5w-40 in. I know people don't have a problem switching from regular oil to synthetic but is it bad for the truck and o-rings to switch back so fast. This is the last time it will happen, but I want to know if there is any residual damage.

 

I don't think so. A lot of folks switch twice a year. I just choose to run syn in mine year 'round simply because I like how my truck runs on it. I went to dino (Delo) and hated it. Switched back to syn Rotella early.

 

Agree with Joe, lot's of people go between the 2 a couple of times a year with no ill effects.

 

Cool, just wanted to know.

 

I have done that switch from dino to syn and back again!
I was concerned about a high oil temp, but ruled out Shell 4W-40 as the culprit.
I would consider getting a used oil analysis from Blackstone they charge like $20.00