What Octane Gas..Do you Use?

[Alex65]

Hi All: I bought a 1997 Mariner 6 HP brand new then. I have always used 93 octane gas from the local pump (w/ 2-Stroke Oil Premix). Seems like it's always been fine, although I did have to have the carb cleaned BIGTIME once. Is this ok? Or should I use 87 octane? The reason I ask is I just bought a new Tohatsu 9.8 2-Stroke & I want to start it out right.<br /><br />Is there more alcohol in 93 vs. 87? Any harm done with 93? Any insight would be appreciated! Just would like to know what "everyone else" uses.<br /><br />Regards,<br /><br />Alex Moore

 

[ZmOz]

Re: What Octane Gas..Do you Use?

You should run the lowest octane your motor is designed to run on. I'm guessing that one is designed to run on 87. I use 93 in my inline six, but that's because when it was made REGULAR was 90 leaded. Using higher octane is not only a complete waste of money, but it will cause carbon to build up faster because it does not burn as complete in a motor not designed to use it.

 

[JB]

Re: What Octane Gas..Do you Use?

I use 91 or better in my Suzuki 4 stroke, Alex.<br /><br />I might save a few bux if I used regular, but:<br /><br />1. My Owner's Manual says run at least 87 octane and recommends premium to take full advantage of the engine management computer.<br /><br />2. I always have fuel left over. I transfer it to my vehicle, which requires 91 or better.<br /><br />I don't think either applies to your engine, so I recommend that you use 87 unleaded.

 

[DJ]

Re: What Octane Gas..Do you Use?

Use 87 in the two stroke Tohat.

 

[neumanns]

Re: What Octane Gas..Do you Use?

Around here everyone I know runs premium. Localy it is the only way to get non-oxeygenated fuel. Oxygenated fuel has a very short shelf life that can lead to gum problems. Not to mention the water dispersal capabilities. Ask for non-oxy i'll bet they point you to the preimum pump. Just my take on the question.

 

[Oldsaltydog]

Re: What Octane Gas..Do you Use?

We have mainly 87,91,and 93 octane gas available at gas stations around here. My motor calls for at least 85 octane gas. I suppose that I could get by with the 87, but I have been using the 91 for the following reasons. If I should not go out boating for a few weeks, the octane level is bound to drop in the tank. Secondly, pre-ignition, quite often inaudible, can wreck a motor, may it be due to older gas or the timing being slightly off. So the few extra dollars seem like good insurance to pay. Fuel dock owners seem to be on the same track -- they usually offer midgrade gas.

 

[DJ]

Re: What Octane Gas..Do you Use?

Two stroke engines gain nothing by using more octane than needed. Four strokes MAY (not always) be a different story.<br /><br />In most parts of the country, ALL fuels are oxygenated.

 

[red10]

Re: What Octane Gas..Do you Use?

neumanns, i run the 92 non-oxygenated gas also up in the north woods, i really didn't know if anybody else used it, i know it's good for the carbs

 

[LubeDude]

Re: What Octane Gas..Do you Use?

I think I would use 87 in the engine in question, as it clealy not concidered a high performance engine.<br /><br />Back in the late seventies, I was running a 85 evenrude on a 15' Ranger Bass Boat, I always used the 100 Octane from Union 76 as it was one of the only leaded premium fuels left. I know now that I wasnt doing myself any favors, but I didnt know any better then. However, I must confess that it sounded a lot smoother with the 100 octane in it. I used regular once and it sounded like it was going to come apart. It never did though. I never had any carbon issues either. Although it was always at WOT. Im running 87 in my 150 merc now.

 

[RJS]

Re: What Octane Gas..Do you Use?

Octane rating is like a shoe size. If you wear size 10, you don't run any faster in size 11.<br />My engine says 87, this is what I use. Using premium is a big waste of money.

 

[Forktail]

Re: What Octane Gas..Do you Use?

You'll get more power running a lower octane. Higher octanes are designed for higher compression engines where pre-ignition is a concern. Otherwise they are a waist of money and performance.

 

[Elmer Fudge]

Re: What Octane Gas..Do you Use?

I have always used 87 octane in my 2 strokes,it worked just fine,i felt that i would only be burning money by using a higher octane rating.

 

[Alex65]

Re: What Octane Gas..Do you Use?

Thanks Everyone! I guess it will be 87 Octane for my new Tohatsu 9.8 HP 2-Sroke! I have always used 93 Octane in my 1999 Mariner 135. The reason is, it's was the best place in Gloucester, Ma. to score fuel & they only have 93. <br /><br />Now...I have a brand new Honda BF150 & it looks like I'll stay with 93 on that engine! Many thanks to all who posted!<br /><br />Regards,<br /><br />Alex

 

[james082273]

Re: What Octane Gas..Do you Use?

I see it posted but no one has really denighed or accepted the point . The point being that as gas sits in a vented fuel tank the octane degrades over time. So if an engine requires 87 and you fill the tank up with 87 before you put it in storage for the winter and take it out in the spring the octane maybe less than 87. Is this not a problem ? I guess a stabilizer would take care of this or always using fresh gas as he would probably do anyway with a portable size engine.<br /><br />What ever grade of gas you use welcome to the proud Tohatsu owners club !

 

[neumanns]

Re: What Octane Gas..Do you Use?

Jon, I think the stability of 92 octane non-oxygenated may be more prevelant here in the north for that reason. Many of our motors spend 6-months waiting for there season. Lawnmowere, snowblowers, chainsaws, leafbloweres boats etc. There are some other properties also that make it Ideal for us northerners.

 

[RJS]

Re: What Octane Gas..Do you Use?

If the fuel sits around long enough for the octane to degrade, I would be much more worried about gum and varnish forming. A fuel stabilizer should be added. Gum and varnish will still form with a higher octane gas; therefore, I would still go with 87.

 

[LubeDude]

Re: What Octane Gas..Do you Use?

The fact still remains, Unless your engine manufacture requires the use of a higher octane than 87, there is absolutly no benifit to using a higher octane, none at all!!

 

[Alex65]

Re: What Octane Gas..Do you Use?

I see it posted but no one has really denighed or accepted the point . The point being that as gas sits in a vented fuel tank the octane degrades over time. So if an engine requires 87 and you fill the tank up with 87 before you put it in storage for the winter and take it out in the spring the octane maybe less than 87. Is this not a problem ? I guess a stabilizer would take care of this or always using fresh gas as he would probably do anyway with a portable size engine.<br /><br />What ever grade of gas you use welcome to the proud Tohatsu owners club ! <br /><br />To: John Boater: I'm really gald I purchased the Tohatsu 9.8 2-Stroke OB. It's a 15" SS & it's weight is only 58 lbs.! Nobody makes a 9.8 that light. Also, 2004 is it's last year of availibilty for the US. Scored a wonderful deal @ $1250.00 (brand new) Looks like all 2-Strokes that don't pass The EPA's rating will be yanked by 2006. Get those 2-Stroke engine purchases before it's too late!<br /><br />Regards,<br /><br />Alex