Any problem putting 92 octane into boat motor?

[TSCTSC]

I have a Yammy 2 stroke oil injected. Is it better to put in 92 or 87? Intuitively, it seems better to put in higher octane, but is there some concerns with carbon deposits or something? What do you guys put in for performance and engine smoothness....in terms of gasoline?

[Surface Tension]

Unfortunitly, non oxygenated gas is only available in a premium blends with the high octane. It won't make any difference in performance in your newer outboard. What the non oxygas gas is better for is shelf life and not deteriorating in your tank and carb thus leaving less varnish deposits. Go ahead and use the oxygas but if your going to store the gas for any period of time use a gas stabilizer.

Most of you are to young or not even born to know that the higher compression engines from pre 1972 and the need for higher octane gas. There wasn't any self-serve gas stations and an attendant pumped the gas for you. This was long before unleaded gas. You had a few picks as to what blend you wanted. In 1972 gas was about 25 cents a gallon, forgive me if that price seems high because I was only a kid at the time with a thirsty minibike. To further date me, I remember the days of asking the gas attendant to put 1 buck of gas in the tank and it would last a nights worth of cruising in my 1965 Le Mans.

Todays gas would eat the diaphragms and gas lines in that old auto. Thats why you'll see pumps stating the Nonoxygas for vintage autos and small engines. So unless you have a Musel Car from the past or are storing gas for long periods of time, the oxygas will be just fine. You can prolong the storage time with a stabilizer.

[river-rat4]

ST-

You must be a REEEAL old feller!!!!!!

I wouldn't mind heading up soon for an education.

Brandt

[Surface Tension]

Brandt, you know I'm not old, just a good memory.

Get up here and we'll get onto the trout an salmon.

[Guest]

Surface Tension - I wish I could have drove around all evening in my roadrunner for a dollar.At 7 miles to a gallon and I got the gas for cost at 17 cents because dad owned gas stations.Its true gas was cheap in 1972,but the hp in my buggy sucked up alot of premium or as some called it HI-Test or ethyl.To bad some of these younger kids today will never have the chance to drive the muscle cars of the sixties and early seventies.I guess this has nothing to do with boat motors,but it was fun remembering.

[Ralph Wiggum]

Yeah, I got the likes of an '84 Plymouth Reliant. Now that was a muscle car

[BIG DS]

The outboards built since 95 pretty much have all been designed to run on 87 octane. Fuel stabilizer is a good idea year around. Keep in mind though, fuel stabilizer will only slow down the break down of the fuel. It will not stop it. During the boating season I would reccommend going to your Yamaha dealer and getting some Ringfree rather than the fuel stabilizer. It is a fuel additive that cleans the engine of deposits and helps to stabilize the fuel. Use only the reccommended amount and only every other tank of fuel. The directions on the bottle say something about a "shock treatment", don't worry about that.

[TSCTSC]

THanks for the responses. But I am still not clear...is it better for my motor to run on 92 or 87 or 89 for that matter? I have been putting 92 octane premium gasoline so far.

[BIG DS]

87. If you want, do the additives. 89 usually has more alcohol in it than the 2 strokes can deal with and 92 tends to leave a lot of carbon and soot deposits in and on the engines.

[Jeremy airjer W]

I use the cheap stuff in everything! And I do use a stabalizer in everything!

The Octane rating is the amount of resistence fuel has to ignite. The lower the rating the easier it is for the fuel to burn. Higher compression engines require higher octane (or a higher resistence to ignite) Because the heat generated by compression would pre-ignite (also known as ping) a low octane fuel (or easier to ignite)

Its just the opposite for lower compression engines. If you use a high octane fuel its harder for the engine to ignite working engine management and ignition systems harder then they need to and resulting in incomplete combustion wich may lead to carbon deposits.

So know we come to the catch 22. No you don't need to run 91 octane, but 87 octane contains 10% ethanol which absorbs moister and breaks down faster! If you are using up your tanks within a month or so go for the cheep stuff. If it takes you a while to use up a tank go with a "non-oxy" premium with a stabilizer (most two stroke oils already have this). If you have been using an oxygenated premium you definitely have been wasting your money!

[TSCTSC]

Ok...so :

87 has 10% ethanol and over time, will absorb water and that is not good when it happens. Otherwise, if it is fresh, it is OK. Right? But can be mitigated with stabilizers? If so, what stabilizers should I use and what is the effect on my motor on using the stabilizers?

92 has higher octane and thus produces more carbon in my 2 stroke than the 87? So that is not good too? But can be mitigated with ring-free additive?

So what about something like 89 or 90 or 91? And how do I know whether it is oxygenated or not?

[tomfromblaine]

TSCTSC what kind of motor are you talkin' about year make model? the last 3 fuels you asked about will almost certainly be oxygenated at least 10%. most water retention comes from having an air space in the fuel tank leading to condensation, keep her full.as far as additives go I'm a seafoam guy and have never had any problems from augers on up.some people use stabil in their last tank of the season, I personally would not put any premium in a average boat motor for the reasons listed in the above replys except if your going to run it hard for a day or 2 pulling skiers or tubers other than that save your money, hope this helps alittle.. "git the net - git the net DOH"

[TSCTSC]

Mine is a 2001 90Hp Yamaha 2 Stroke Oil Injected. I use the boat about twice a week during the weekends and I pump in gas approximately once in 2 weeks. Currently using only Ring Free Additive and putting in 92 octane premium gas. So, should I do different now and just use 87 or 89?

[tomfromblaine]

Just use 87 unless your going to be realllly workin' that motor, I don't know much about yamaha ring free but the chemical called techron has been popular in the auto industry for de-carbonizing injectors/combustion chambers/rings so I'm just guessing but I'll bet it's the same or really close to it,, if thats the case she's pretty strong stuff, Chevron has it in their gas but in very small amounts, just follow directions on that stuff or use 1/2 of the recommended dose if you feel the need to treat every tank most of all just keep your tank as full as you can when you remember to. just remember that a "little" prevenative maintance goes a really long ways towards longevity and reliability you really don't want to over do it or you'll just stress yourself out and your toy becomes not as fun, in otherwords just fill her up and go fishin' hope this helps a little

[tashit]

Even if you really are working the motor, is it still advised to use a higher octane? I thought this would only be necessary if you were working the motor hard AND experienced knocking/pinging as a result? As long as there is no knocking/pinging, I don't know of any reason to use 92 octane (aside from the 10% ethanol issue).

[BIG DS]

Switch to the 87, stay with the ring-free, and it sounds like you are using the fuel up fast enough so you shouldn't have any moisture or fuel degradation problems. Check with you dealership this fall as to winterizing you motor.