Synthetic two-cycle oil
 

Pre mix or oil injection? What engine?

Oil injection, 1992 Yamaha 150

Personally I would not mix it with the old oil, but wouldn't hesitate to run it. Try and run your tank empty, and then fill up with the synthetic oil. Some synthetics don't mix well with mineral oils is why I suggest that.

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.

Gotta agree with Ferm 100%. It even says on the side of the bottle that they can be mixed with regular oil. I've never had a problem with using synth., although the extra price keeps me using regular most times. When I can find the synth on sale I'll buy it though.

I don't know. $38 for a gallon of Yamalube compaired to $18 for a gallon of Penzoil at Walmart. I used to be a hardcore believer of Yamalube but at those prices you would be a fool to run it.

Every once in awhile wally world has the pennsoil full synthetic on sale for less than the blended stuff to get it off the shelves and new inventory in.

Exactly.

The usual Pennsol that I see wally world having on sale is a blended synthetic btw.. not the pure synthetic. But it's a great oil and I agree with Pete that when it's on sale it's a great bang for the buck. http://www.walmart.com/ip/Pennzoil-M...1-Gal/16401577