http://maintenance.yamahaoutboards.com/engine-oil-lube/All the things you hear from these old school mechanics, or new school who have been taught incorrectly…like synthetics are too “slick”, wont allow rings to seat, etc. is complete horse hockey pucks. Yamaha sells synthetic oil for a reason. After the initial change, there is no reason not to put synthetic in it. The only reason to change the first 20 hours is to remove contaminants from parts seating in. Most importantly, ALWAYS get your engine up to normal operating temperatures, usually by running it hard for 10 minutes or so, in order to evaporate the fuel and water that makes it past the rings in ANY engine during the combustion process. The way we fish, which is typically running the engine for 2-5 minutes at a time moving from spot to spot, is not adequate to evaporate stuff in the crankcase, thus the smell of fuel in the crankcase oil. There are a bunch of reasons to use synthetic oil, mostly related to its ability to withstand higher temps and shock resistance than conventional oil. It lasts longer too. With todays oils, the old rule of changing every 3k miles in your car is a complete waste of both money and a valuable resource. The only exceptions are if you run in extremely dirty environments, or are always just running down the street to the store and the oil never gets up to proper temps. Even then, synthetics are less subject to breakdown from fuel dilution.2017 Sabre FTD AE DC2017 Yamaha 175 SHOMK Fortrex 80Helix 10 Mega SI in consoleHelix 7 GPS SI GN2 on bow
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