[THEFERMANATOR]

Originally Posted by jasoncooperpcola

West marine had their synthetic on sale a couple years ago. I asked about using it for the Johnson. The salesman told me that once you run synthetic you cannot go back to conventional. Personally i wont run synthetic in any engine of mine unless the engine was broke in with it Or does not have high mileage.

COMPLETE BS. There is nothing that says you can't go back and forth between the two. I ran the pennsoil synthetic blend, but sometimes would get stuck with the full synthetic and never had a problem(pre mixing). Only issue I have heard of with going back and forth was that some of the early synthetics used a synthetic base oil that would actually react with the mineral base oil and create a fiber like substance that would plug the oil injection system(seemed the synthetics that were red were the most prone to this), and this is why I won't mix it in an oil tank. Synthetics are not reccomended for engines with no or low hours on them as the synthetic oil is so slick it can prevent the rings from seating. Other than that there is no trouble in running synthetic. Personally I liked the reduced smoke of the synthetic and synthetic blends.