87 Octane Gas and 2-Stroke Engines?

Dave A · Post by **Dave A** » Thu Apr 21, 2005 9:35 am

Have any of you encounterd problems with your outboard when you put 87 octane gas in the tank. On a trip to clear lake last week I inadvertantly put 87 octane in the tank and the motor would start up and die. Usually I will use a higher octane gas. Anyone have this problem? I have a Merc 115

Fishin' Dave · Post by **Fishin' Dave** » Thu Apr 21, 2005 9:44 am

Call Mike or Drew at Boatmasters. I used to have a 90hp merc and he told me to run 92. He's the best mechanic around, so...? Go fill up with Cheveron.

Justin · Post by **Justin** » Thu Apr 21, 2005 10:19 am

I have a 225 optimax and i have only ran 87 octane from chevron only though. I have never had a problem with my motor not starting or dying. Maybe you got some bad gas. You should only run popular stations like chevron, shell, or 76, atleast you can kinda trust them.....

> Have any of you encounterd problems with
> your outboard when you put 87 octane gas in
> the tank. On a trip to clear lake last week
> I inadvertantly put 87 octane in the tank
> and the motor would start up and die.
> Usually I will use a higher octane gas.
> Anyone have this problem? I have a Merc 115

Hitman · Post by **Hitman** » Thu Apr 21, 2005 11:12 am

Could be a bad tank of gas or built up condesation if you store your boat outside. Ask your mechanic about the risks of running higher octane gas in your 2 stroke. I've been told by Mercury and several mechanics that running the higher octane gas raises cyclinder temprature which would lead to piston or cyclinder wall melt down. Just a heads up....

I run a 225 Opti and ran 89 for 3 years - I just blew the power head in Jan! I now stick to 87 octane per the advise of Mercury.

Hitman

Cooch · Post by **Cooch** » Thu Apr 21, 2005 12:14 pm

that we run the lower octane gas in these outboards due to over heating issues. It's one thing to run the high octane in a racing machine, it's a whole nother story to run em in our engines with the constant stop and go.

I've run low grade 87 Octane in every single OMC/Johnson/Bombardier motor I've ever owned, and not once have I had any problems associated to running low octane gas. It's what my owners manual recommends.

Quite frankly, I don't see how anyone can trust a mechanic, I don't care what his reputation is, that tells them to run higher octane in our bass boat motors, when our hand book and owners manual says the opposite! Who do ya think is gonna be responsible for that motor when it blows cause it over heated running too high an octane gas? Most definately not the manufacturer, and yer mechanic will bail on ya too, I promise you! You'll be the one footing the bill for the repair.

Follow your book guys, what ya read there, is yer bible to efficient and safe motor operations.

Cooch

Paul W · Post by **Paul W** » Thu Apr 21, 2005 3:51 pm

I have never heard of any commonly used outboard to require anything over 87 regular unleaded. Even the new Verados dont require premium gas. My 115 4 stroke Yammy runs perfect on 87....it hast to be something else....maybe bad gas?? Water??

Paul W

Mike A · Post by **Mike A** » Thu Apr 21, 2005 4:06 pm

I've been running 89 in my 150 Mariner for the first 9 years of its life, with NO problems! (knock knock). You mean I could have saved .5 cents a gal all of these years? Man I could of bought a new boat by now! I think its all in how you break your motor in. I did mine wide open! (really) break it in like your going to run it, so it does'nt go into shock when you open it up!

saLTIE- · Post by **saLTIE-** » Thu Apr 21, 2005 7:12 pm

Billie T · Post by **Billie T** » Thu Apr 21, 2005 7:27 pm

I had a old 86 Skeeter Starfire 175 with a merc 175. I ran nothing but 87 octane for 15 years before the power head let go. I now have a new Skeeter ZX200 with a 200 yamaha and I run nothing but 87 ocatane again, no problems. Now here is another thought!! People say you have to use nothing but Yama lube for your oil, not true!! When I was down at Havasue fishing WonBass pro-am. I talked to a Yamaha rep about oil. I told him that I buy my oil at Walmart for 6.38 a gallon. Could I be hurting my engine? This is what he told me:: As long as it is TCW3, you can use it. BUT, do not mix different brands together. What happens there is the oil will thicken up and not blend together, thats when you have problems. My Yamaha has 235 hours on it and no problems. Just thought I would pass along that info.

Andy Giannini · Post by **Andy Giannini** » Thu Apr 21, 2005 9:04 pm

> If you see a tanker semi rig at your favorite station and are thinking of filling up the boat, go across the street anywhere else. Specifically, if the station is being filled with gas, try somewhere else. Anything bad in the station tank is going to get an enema. Dirt, water, rust, is getting blasted around as the fill nozzel from the semi is going many gallons per second. They have filters, but why risk putting crud in your favorite boat? It takes a good while for the tank to settle down, the sediment go to bottom etc.

Food for thought,

A.G.

Tim · Post by **Tim** » Fri Apr 22, 2005 2:22 pm

Andy is right about not fueling when the Tanker is dropping fuel at a Service Station. It isn't wise for your car/truck either. All gasoline tanks have water or other contaminates in the bottom. There is usually 150 to 300 gallons below the pickup line in the tank and that is where the water (from condensation) and other particles reside. When you dump the new gas in from the top of the tank, it stirs eveything up. It doesn't take long to settle back down, but the filters don't always catch the water. In the old days, we checked our tanks with a special paste that turned red to indicate the level of water. If it was within 50 gallons of the pickup line, we would have to pump it out. I am sure the filters are much better today, but it isn't worth having the problems by taking a chance it won't happen. Feeling lucky???

> Food for thought,

> A.G.