Okay, so about 2 months ago my dirtbike motor seized up so i had to get it rebuilt. When it was rebuilt, i noticed blue smoke, and the speed was decreasing so i decided id better take a break for a while. I called the person who rebuilt it and he said i should try 20w50 because its thick and wont get into the rings. Then after its burned i go back to 10w40. Should i do this?