I switched over to a synthetic oil in my scrambler400, and the thing started smoking terriable. At first i thought maybee i was running two rich, checked the plug and everything was okay, so I drained the syntetic oil and put in the regular oil. No smoke. It was pennzoil synthetic from walmart, says it is for marine use, but is still a tcw3. It shouldnt make a difference, heck you would think it would smoke less being for marine use.

 

I changed over to Penzoil myself and I have also noticed some extra smoke, I was told by a mechanic an my Polaris Dealer that as long as it was TCW3 it would work. My Explorer seems to be running fine.

 

I run the Pennzoil marine in my old Suzuki triple motorcycle and it does smoke more than regular. But as long as it is synthetic and it is rated OK then you dont have to worry.