I am getting my new boat in a few days and I downloaded the owners manual for the motor (Yamaha 90 HP 2-stroke). Yamaha says to not only fill oil reserve, but to mix the 50:1 in the fuel tank for the break-in period (first 10 hours).Do I fill the entire 41 gallon tank with mixed fuel?Do I mix ratio in 5 gallon gas can and pour one can at a time in the boat tank or dump oil in boat tank and fill at gas station?Thanks...always had i/o
What I would do is buy a couple of gallon jugs of Yammy TCW 3 or whatever they recommend. Since your fuel/oil ratio is 50:1 that means 1 gallon of oil to 50 gallons of fuel. Soooooo start out with 25 gallons of fuel (since your tank holds 41) and mix with 1/2 gallon of oil. I eyeball the gallon jug & mark on it with a magic marker. Pour in 1/2 a jug & add 25 gal of fuel & run it. Watch the fuel Gage to get a feel of consumption and repeat as needed. For pre mix quantities of less than 25 gal I use a plastic container that has the oil quantity to fuel in gallons marked on the side. These are available at most marine stores.
I'm going to assume that you'll burn the 40 gallons and more in the break in period. I'd mix up the whole tank at 50:1 and do a whole second (and third) if needed. If you have some pre-mix left in the tank after the break in period, it's no big deal as-is, and even less of a big deal if you then top off with unmixed fuel.I'm a little obsessive about the mix. I think that if your fill tube allows you to directly spray the bottom of the tank with full force of the fuel hose, just put in the proper amount of oil (about 3.5 qt for 40 gal) in the tank and mix it up with the fuel flow as you fill the tank.If you have a fill tube that doesn't allow this (most likely), I would recommend that you put the 3.5 qts in a 5 gallon can, mix it thoroughly with 5 gallons of gas, put that in your tank, and top off. This will ensure the oil is mixed thoroughly. A lot of people would say that you could just put the oil in, put the gas in and natural motion will mix it up. Like I said, I'm too compulsive for that.You might just want to do this in increments of 12 gallons (e.g put in 36 gal rather than fill it) because it's 1 qt. oil per 12 gallons gasoline. You'll either be buying the TCW3 oil by the quart or by the gallon - which will have quart markings on the jug. Don't worry if your mix is a little rich. Have fun.