93% Octane Gas

[Rubberduck#2]

Someone told me it was good to use 93% octane gas in boat motors and I have heard some people say not to. I have a 200 HP Mercury, can any of you experienced boaters tell me if it's good or bad?

[macgyver]

What year was the Motor made? Not that I can help, but that's one of the first questions the experts will need to know. From my understanding on some of the older motors it was a good idea, but the newer ones are computerized so the 87 octane is fine. Some of them it is a BAD idea for. I believe zooker had a problem with too high of octane, and it building up a bunch of carbon. Costs a few bucks to have it cleaned out I beleive. If these guys can't help, go to the Mercury web site, and ask them, or this is a good link for boat info http://www.bassboatcentral.com

Lizards

[jeffman]

RUNNER,

Â* Â* My mechanic told me that the new Merc's are designed to run on 87 octane gas, and any higher octane will not help. He advised me to use Mercury top grade lube ONLY, as it has additives that keep the carbon from forming in the cylinders.
Â* Â* He is factory trained by Mercury, Evinrude and Yamaha, so he is not telling me that as a Mercury only mechanic.

JackL

[bearpaw]

I must agree with Jackl. Evinrudes are being made for 87 percent. Any higher may cause carbon build up as well as higher cost to the purchaser.

[Rob Mak]

almost all of the japaesse made moters-yammaha,honda,susuki,ect. are tuned for 86 octane- running 87 octane is fine. i know for a fact that there is no adjustment to change this. odds are most newer moters are the same way. regaurdless of who makes them.

i had to have the head removed and the mechinc scrapped the carbon build up out of my cyclinders which was not good. thank fully it was under warranty i think i had the boat less than a year at that time. all caused by running high test gas. i used to have and old 'rude 70 horse that loved it's high test. mainly because it was a anicent beast. i belive it was a 59 model-boat had fins like a 57 chevy- Â* Â*

i reread the yamaha booklet after this thinking i missed some thing about using 87 octane only it does not it simply states that "this moter uses 86 octane or higher" kinda leaves alot unexplain don't it?

zooker

[Rubberduck#2]

My motor is a 1987 model. I was told it was good for the old motors but was unsure. I guess to be safe I will use the low grade gas.

[okefenokee010]

My mechanic says that the high octane gas will tear up the insides of my Optimax. He said just run the regular.

[Makitcnt4u]

How often should I add that yamaha fuel additive to the gas also?

How many ounces would I need for a 62 gallon gas tank?

[redneck13]

When I bought my Yamaha earlier this spring, I was told to use 87 oct. and add Yamalube oil.They also sell several brands of outboards,so I figure I'm getting the straight stuff on the oil.

[NorthNJangler]

I have 91 Merc, and I can tell you first hand you can tell a difference with the lower octane, the motor runs a little rough with the low octane (its 86 octane out here). I put premium in and run a lot better.