Mixing the gas with oil

kevinclark93 · Mar 23, 2011

A mechanic told me the other day I should remove my oil pump and mix the gas. He said it is the best way to go. I wanted to get some feedback on the subject. I know mixing the gas is the safest option as far as oil getting to the motor, but are there any drawbacks other than you have to poor oil in your tank every time you fill up.

I have a 96 150 mercury

Chris1956 · Mar 23, 2011

Re: Mixing the gas with oil

The only drawback is knowing how gas you want to turn into 50::1 fuel. The easiest way is to guess how much gas the tank will take, in six gallon increments. Now add the proper oil (1 pint oil/6 gal gasoline)and then the proper gasoline for that much oil. Now guess if it will take 3 more gal of gas. if so, mix in 8 oz of oil, and then the gasoline. That will put you within 3 gal of having a full tank. If you need to fill it up more than that, you willl need to mix up 3 gal fuel in another container and top off the tank.

j_martin · Mar 23, 2011

Re: Mixing the gas with oil

One other drawback. The pump mixes less oil at low throttle, so at 50:1 you'll burn more oil and make more smoke than necessary.

Silvertip · Mar 23, 2011

Re: Mixing the gas with oil

If you have a functioning oil injection system there is no reason to disable it. Like anything, pay attention to the amount of oil being consumed. Each six gallons of fuel should result in approximately a pint of oil being drawn from the system. The injection system has alarms associated with it. Learn what they are and if the alarm goes off, don't run the engine until you determine what the alarm means and then have the problem corrected.

1nebel0 · Mar 23, 2011

Re: Mixing the gas with oil

Do what the veterans do....buy the dummy plug from Merc, take the pump off, take the tank off, plug the pipe threaded plug on starboard side that pressurizes the on board tank, and never, never worry about pump failure. It's all good that you have alarms but it does not good when you get stuck with no one around. You will never burn your motor up!!! I have every motor I own disabled. When the system works it works but why take the chance of failure and toasting a motor... just my opinion but Merc sells alot of dummy plugs.. This has to be used when you take the pump off to keep the plastic gear in tack on the crank shaft...do a search here and it is explained many times over..good luck

kevinclark93 · Mar 24, 2011

Re: Mixing the gas with oil

Thanks for the feedback guys.

If i mix the gas and the boat sits for a period of time does the gas stay mixed or is there separation of the gas and oil.

Chris1956 · Mar 24, 2011

Re: Mixing the gas with oil

Mixed Gas and oil will not separate, ever.....

Silvertip · Mar 24, 2011

Re: Mixing the gas with oil

1nebel0 said:
Do what the veterans do....buy the dummy plug from Merc, take the pump off, take the tank off, plug the pipe threaded plug on starboard side that pressurizes the on board tank, and never, never worry about pump failure. It's all good that you have alarms but it does not good when you get stuck with no one around. You will never burn your motor up!!!

You'll NEVER burn your motor up????? One should learn NEVER to say NEVER. Doesn't matter if the engine is oil injected or premix. Lubrication failures do occur much more often than realized.. Many techs blame lubrication failures on the injection system when it is in fact a fuel delivery problem. Lean carburetion burns down more engines than injection systems. If the engine is starved of fuel it is starved of oil as well and it doesn't matter if it's injected or not.

1nebel0 · Mar 24, 2011

Re: Mixing the gas with oil

silvertip, while your statements are true we are talking about oil pumps...yes you can burn down a motor for all the reasons you state but he is talking about mixing or not...you will never burn down a motor due to pump failure if you aren't using the oil pump...that is the only point I was trying to make.....of course more engines burn up due to lean conditions, stale fuel, phase separation and many other things other than oil pump failure. I choose to take that piece out of the equasion and deal with all of the other things that can toast a motor. My fuel is disposed of after season not stored, my max timing is retarded two degrees from Max and I have fattened up my main jets on my Carb motors to do my best to make them last...No oil injection being used on Mercury Motors for the insurance factor...

kevinclark93 · Mar 25, 2011

Re: Mixing the gas with oil

Again guys thanks for all of the feedback...

You'll NEVER burn your motor up????? One should learn NEVER to say NEVER. Doesn't matter if the engine is oil injected or premix. Lubrication failures do occur much more often than realized.. Many techs blame lubrication failures on the injection system when it is in fact a fuel delivery problem. Lean carburetion burns down more engines than injection systems. If the engine is starved of fuel it is starved of oil as well and it doesn't matter if it's injected or not.

What are the warning signs of running lean?

Chris1956 · Mar 25, 2011

Re: Mixing the gas with oil

The most obvious sign of running lean is ruined pistons and rings. You will notice that when the motor won't start because of low compression.

Inspect the color of the spark plugs. If they are dark brown or lite brown, you are probably OK. If white or green, it is likely running lean, pre-detonating or overheating.

sschefer · Mar 25, 2011

Re: Mixing the gas with oil

Silvertip said:
If you have a functioning oil injection system there is no reason to disable it. Like anything, pay attention to the amount of oil being consumed. Each six gallons of fuel should result in approximately a pint of oil being drawn from the system. The injection system has alarms associated with it. Learn what they are and if the alarm goes off, don't run the engine until you determine what the alarm means and then have the problem corrected.

Agree, if you haven't torn a motor down and don't know how a 2 stroke Merc works inside and out, leave the darn pump on. The odds of you leaning your motor out with too much oil in the fuel are about 100% more likely than a pump failure. These pumps are highly reliable and rarely fail. You only hear about the ones that fail on this board and not the ones that have 1000 hours on them with no problems.

Telling you to cap it off and plug this is and that is not the way it needs to be done. You need to split the case and fill the space back up where the driven gear and shaft were. You also need to remove the brass bearing in the bottom of # 2 cylinder and fill it up. Yes, you can by the kit that is supposed to take up the space and hold the bearing but if you've been inside you'd know that's just a minimal solution.

Mixing the gas with oil

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