Mixing oil and gas

marauder11

Petty Officer 2nd Class
Joined
Oct 10, 2011
Messages
176
Have just gotten a new boat and am wondering if i can fill my tank and then add 2 stroke oil after i see the amount of fuel it takes. Will it mix ok . I know it might sound stupid but just wondering the best way to achieve the best mix.
 

BonairII

Commander
Joined
Jun 7, 2011
Messages
2,727
Re: Mixing oil and gas

It will mix just fine. I would assume that most people put gas in first THEN oil....unless the tank is empty.

Just make sure you don't fill it so full that you can't fit the proper amount of oil in.
 

rfdfirecaptain

Petty Officer 1st Class
Joined
Aug 17, 2008
Messages
314
Re: Mixing oil and gas

I am assuming the gas already in your tank was mixed with oil at the appropriate ratio. Here what I did with my old two stroke. I would fill the tank until the gas handle clicks off. The add the oil for the amount of gas shown on the pump. Then add just a little more gas to wash the oil off the side of the gasoline fill tube.

As far as it "mixing ok"... sloshing around in the tank on your way to the dock from the gas station should take care of that.
 

Mikeyboy

Chief Petty Officer
Joined
Mar 15, 2012
Messages
475
Re: Mixing oil and gas

You can do it that way if the tank is not empty. I try to put oil in first so it mixes as I put the gas in but you can't always do that. If you are using a portable tank after putting gas and oil in you can shake the tank to ensure it mixes but if that's not an option you should still be ok.
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
28,141
Re: Mixing oil and gas

If it is a large tank, and you need to add lots of gasoline, I recommend you add 1 qt of oil and then pump in 12 gal of gas. Repeat until you get near the top and then add a pint of oil and 6 gal of gas or 1/2 pint of oil and 3 gal of gas. It will mix best this way....
 

JimS123

Fleet Admiral
Joined
Jul 27, 2007
Messages
8,282
Re: Mixing oil and gas

My tanks are all "calibrated". I know how much gas they will need to fill them up. Simply add oil for X gallons of gas, then add X gallons of gas. The force of the gas pump will mix the oil.
 

Sea Rider

Supreme Mariner
Joined
Sep 20, 2008
Messages
12,345
Re: Mixing oil and gas

The best way to replenish a 3-6 gal portable tank is to have it marked at each gallon at the dial, that way will know how much gasoline/oil to add for that outing without any spill. Adding gas first and oil second or viceverse makes no difference if refilling tank with at least 1/2 gallon leftover on bed tank. The drive from gas station to boating facility will mix it al right.

Happy Boating
 

Georgesalmon

Lieutenant Commander
Joined
Apr 14, 2012
Messages
1,793
Re: Mixing oil and gas

I have a 30 gal tank. Mixing the oil and gas inside the built in tank still bothers me a little but I do it. However I put a pint of oil in and then add 6 gallons, then stop add a pint of oil then 6 gallons, etc. I know my gas gauge pretty well with the boat on the trailer and when I get close to full I still add a pint of oil and 3, 4, 5, gal gas whatever it takes. I would rather be a little oil rich than oil lean. Got an old 1979 engine and want to protect it. I know, I know, to cautious. I also use marine sta-bil because I like their TV adds.
 

Home Cookin'

Fleet Admiral
Joined
May 26, 2009
Messages
9,715
Re: Mixing oil and gas

I agree with George and Chris--oil first then gas. You'll feel better knowing that at worst, you have a little too much oil. But don't overthink it. It's not rocket surgery. The boat won't know, and doesn't care, if it's 48:1 or 52:1--or even way greater tolerances.

Never rely on a boat fuel guage for anything except "E". And don't forget to put the stabil in first, too.

To answer the OP's question, no you can't fill the gas then add oil, b/c "full" is full. But I know that's not what you meant, but from experience, it's very easy to top off a tank, in-hull or loose, unintentionally.
 

duke33

Petty Officer 1st Class
Joined
Apr 2, 2012
Messages
353
Re: Mixing oil and gas

Mixing is a scary issue. I've ran chainsaws, weedwhackers, and assorted other 2-stokes. The gas will mix either way. The crucial part is the proper mix ratio. It's been very well described above. Thanks Guys.
 

pootnic

Chief Petty Officer
Joined
Aug 11, 2007
Messages
447
Re: Mixing oil and gas

You could use liters where you only have to times the gas number by 20 to get the oil amount(ml):)
Or times by 2 and add a 0 for your oil in ml's.
 

marauder11

Petty Officer 2nd Class
Joined
Oct 10, 2011
Messages
176
Re: Mixing oil and gas

You could use liters where you only have to times the gas number by 20 to get the oil amount(ml):)
Or times by 2 and add a 0 for your oil in ml's.

Well i like this being in Canada that will be easy math. That is if i forget my idiot bottle as my dad calls it lol.
 

saxrulez

Petty Officer 1st Class
Joined
Apr 10, 2010
Messages
286
Re: Mixing oil and gas

I honestly don't put the oil in before the gas and never have. Haven't had an issue yet. Mine is only a 12 gallon tank and I think I've only ran it empty once or twice. Those are the only times I'll put the oil in first.

I feel like if I still have 3-4 gallons of the correct ratio mix in, adding the other 8 gallons then adding the oil isn't going to be an issue by the time I get to the boat ramp. Starting and stopping the trailer, unhooking everything, backing down the ramp, I'm pretty sure it is well mixed by then.
 
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