I run a pair of 300 ProMax oil injected and fuel injected outboards on my ChrisCat. I was low on gas and had to put in some of the midgrade additive added fuel here in Michigan. Will it hurt the engines, and what should I do, I have since put in 93 octane fuel.

Thanks Ron Luks

add some toulene and bring the octane up

Technically, you should not have to run the high octane in those particular motors. If they are just standard Pro Max 300's. Only the Bridgeport engines over 260 Hp require better fuel. You will see better fuel economy though with 92+ octain. But not enough to justify the higher price. Something else you should consider doing is removing the oil injection. Pre-mixing your fuel is always a better deal, though not as convinient. Mercury makes a plastic plug for the old pump hole in block. Make sure to get the "long" one to hold in brass bushing. Powerhead removal is not nessesary. 16 oz's of oil to 6 gallons of fuel. Hope this helps !!!!!!!!!!

RainsPerformanceMarine
Afton, OK

Thanks for all the info, I do have the 300 HP ProMax's, I only burned approx. 40 gals of the lower grade (mixed with approx 40 gals of 93) leaving approx 40 gals in the tanks, and have added 100 gals of the 93 octane. With what I have read I guess I should be alright. I forgot all about tolulene, I used to run it years ago in my drag cars, old tricks never go away, with the price of gas now it makes sense to buy tolulene.
Thanks Ron

Technically the gas you bought has ethanol,not methanol,the main thing besides octane is it leans out your motor but most gas now has ethanol in it. I looked for tolulene myself a few weeks ago and most places no longer have it. Tolune is 110 octane,race gas does the same thing for less if you wanted to boost your octane,Smitty

Artic go to your local Sherwin Williams paint store they'll have it we pick up 55 gallon drums from ours .in a pinch Menards sells it also you can pump 87 to 100 octane for pennies on the dollar . 700 gallons 87 octane and add 110 gallons toulene

The oil injection on the 300 pro max has proven pretty reliable why would he remove it?
Not just the "bridgeport" motors that have over 260 horsepower require higher octane fuel.

I've been using TORCO Accelerator $$$ but tought about going the toulene route.
How much does a 55 gallon drum sell for?

UPROKTOY.................some people never learn do they......A stock promax does not require higher octain fuel. You need to do your research on compression in the 300 PM. Do you know what that is????? I have probably forgotten more about outboards than you will ever know............

Here in good old CA, we are limited to 1 gal at a time.



Darrell.