Why are you running 20w 60 oil in the first place?!?! Thats about the consitency of Molasses on a cold winter night! That oil is almost the consitency of gear oil. Anyways, besides that, it could be possible that you have a bad seal, or one of the seals was put in incorrectly. But their are many reasons that you could be buning oil... are you sure its burning oil, or could it be your exhaust?
Bookmarks