There is exactly zero benefit to mobil 1 over Yamalube 4M. Without starting an "oil war", at the Yamaha school, they talked for FOUR days about different lubricant qualities and what they do inside a running engine. Different engines have different needs. An outboard will run at redline (6000 RPM) for hours on end, full throttle, full load. A car engine--runs at 1/4 load or less, low RPM, and low throttle input. And it has air passing around the oil pan to help regulate the oil temps. Outboards don't have that luxury, so they use seawater for the oil cooler. The bad part is that seawater isn't always the same temp. Those in the Northern states might use theirs in water temps in the 20's and 30's, those of us in the South might see water temps in the 90's, so the engine oil temperatures can vary a LOT more than a car's engine oil temp (which is usually around 200 deg most all the time). For those reasons and a LOT more, yamaha recommends ONLY the fluids and filters that are yamaha branded.
The filter and no fluid change was an issue brought up at the meeting as well. Just change the filter at each oil change. Does no harm aside from costing $12 and change. Don't use a Fram. Use the correct Yamaha filter; it's slightly more $$ but how much do you value your outboard, and how badly do you want to avoid sitting out in the middle of the lake with a blown motor, flagging your hands to get anyone to tow you back to the ramp? Hopefully that tow boat is yamaha powered; if not, you'll never hear the end of it. LOL!
In the owner's manual, there's a maintenance log chart. Keep log of your maintenance. Don't forget the water pump impeller once a year.
If for some reason you sell the motor and upgrade to something bigger, or whatever, that filled out maintenance chart typically adds a few hundred dollars to the value of the motor.
