Hi Randy.. I use a biodegradable oil in my Seagulls, mainly because they require a high gas-oil mix in the older engine (25-1) My two newer engines (1989 & 1992) are the QB series that recommend a 50-1 mix. When I bought Stargazer, she wore a 1987 Evinrude 8hp Yachtwin, longshaft. The owners manual recommended 100-1 gas-oil mix. I called Evinrude tech support to order a service manual and info on the alternator that was in it. We also talked about the gas-oil mix, and they recommended that I use a 50-1 mix, as they were getting a lot of warranty repairs when 100-1 was used. I compromised with a 64-1 mix...2 oz. in a gallon. Their website also touted their synthetic oil, and I bought a gallon (only size available !!!). After 5 years, I still have over 2 quarts left...and I use it in several other 2 cycle garden engines as well ! Penzoil makes a synthetic...West Marine only sells it in a gallon size, but after relating how Mobil 1 saved the engine of my Pathfinder, I have little trouble selling it over oil costing a half as much. ( I work P/time at W-M). I've seen the Penzoil synthetic at WalMart in quarts, as well as a 100% synthetic lower gear oil that I'll use instead of the synthetic blend that I now use. Perhaps I'm going a bit overboard in both gas-oil and tranny oil, but I use so little that the cost isn't a factor....and I love my Seagulls like I love Stargazer<GG> I've thought about Amsoil, for both car and boat use, but would have had to order from the factory as there was no dealer close by. Do check into the 100-1 mix. My Seagull manual suggested breaking it in at a 25-1 ratio for the first 10 hours. I've talked to 2 Seagull sales and service shops and they suggest I not use the 50-1 mix. Perhaps they're mired in the 10-1 and 25-1 ratios of the original and mid-life models, but I again compromise by adding a tad more oil (3 oz instead of 2.6 oz.) Harvey/ Ga M-17 Stargazer #294