Fuel mixing with the boat rocking action

[johnyrude200]

So, I have read in the old owner’s manuals that when mixing fuel, to add the oil as you’re filling the tank. Well, my question is what difference does it make once you drive down the road or start using the boat? Doesn’t the rocking action of the boat equalized the mixture regardless?

I mean – thinking back to my chemistry classes in college & high school, a mixture will come to an equilibrium when stirred continuously….sort of like chocolate milk does when you add the syrup and stir long enough (even the stuff that sticks to the edge of the glass eventually dissolves into the solution………)

In a 6-gallon tank, this is simple. In a big tank such as 95 gallons, I can see why adding 1/2 the oil when 1/2 full might make sense, but even with that the constant sloshing of fuel inside the tank should make the solution equalize…….

• This topic was modified 4 years, 9 months ago by johnyrude200.

[frankr]

Modern TC-W3 oils mix much more readily than the old 30 weight stuff, so I don’t think the issue is as great as it used to be.

[Tubs]

A "Boathouse Repair" is one that done without having tools or the skills to do it properly.

• This reply was modified 4 years, 9 months ago by Tubs.

[johnyrude200]

Tubs, driving down the road with the boat on the trailer has plenty of rocking action every ime you speed up or slow down….wouldn’t that act the same way?

[fleetwin]

Well, the only thing I would say is not to add the oil last, after filling the tank with gas….I’m sure it is fine to add most of the oil midway through filling the tank with gas, adding the rest of the gas should promote proper mixing.
But, I guess you never want to add the oil first on an empty tank, there is a good possibility that the pick up tube will get a good gulp of solid oil before proper mixing takes place.

[reivertom]

I never even thought of not shaking the tank around if I add oil after the gas. I usually try to put the oil in first and watch the gas pump to fill to the amount I want.

[johnyrude200]

Staying on topic – the question was for a big tank, not those little 6 gallon ones where they are easy to just shake up a couple of times.

So in summary – add 1/2 tank of fuel (i.e. 48 gallons), add your oil, then fill the last 48 gallons of fuel. I’ve been doing 1/2 tank gas, 1/2 of oil, then 2nd 1/2 of fuel, top off with the last 1/2 of oil. 1 gallon of oil makes 42 gallons of gas at 50:1, so I use 2 gallons of oil for each fill up in a 84 gallon tank.

There are 7 pints in 1 gallon, or 16ou. of oil per 6 gallons; so 7×6 gallons = 42 gallons of gas per 1 gallon of oil.

Thanks for the help, wanted to make sure my line of thinking wasn’t doing harm……..

• This reply was modified 4 years, 9 months ago by johnyrude200.

[lindy46]

My tank is built in on my pontoon, so I never add gas/oil to an empty tank. There are usually 5-6 gallons in the tank when I fill up, and I add the oil first, then the proper amount of gas for the oil I have added. Never a problem.

• This reply was modified 4 years, 9 months ago by lindy46.

[Tubs]

A "Boathouse Repair" is one that done without having tools or the skills to do it properly.

• This reply was modified 4 years, 4 months ago by Tubs.

[Mumbles]

With a built in tank, you have to rely on the boats motion to mix the mix.

[Author]

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