What octane gas do you put in your boat?

(whazzup) · (whazzup) **Join Date: Oct 2001** 06-08-2003, 4:26 PM

I know most manufacturers reccommend at least 89 octane but will 87 octane really make that much of a difference? Maybe its a conspiracy between oil companies and boat engine manufacturers?

(wakeeater) · (wakeeater) **Join Date: May 2002** 06-08-2003, 4:37 PM

wat ever is the cheap one. don't know since i don't pay for it yet. i m pretty sure as long as u don't have a upgraded engine 87 should be fine thats all we put into my friend house boat and that engine is workn harder then a ski boat

(bob) · (bob) **Join Date: Feb 2001** 06-09-2003, 12:42 AM

my boat recommends 89 and i think many of the newer ib/v drives also do, read your manual since running with an engine pinging/knocking can lead to its early demise.

fun9c1 06-09-2003, 7:12 AM

It depends on the motor and how the timing is set. On newer motors, it's controlled by the computer. You're wasting your money using any octane higher than it's programmed for. Higher octane is useless without an advance in timing. If you use a LOWER octane than it's programmed for, it should retard the timing when it senses pinging and shouldn't do any damage, although you won't be getting all you can get out of your motor.

On my old carbureted and point ignition motor, I can change my timing to what octane I want to use.

Every motor's different. If you don't have any literature that tells you, MC can tell you.

(vortech347) · (vortech347) **Join Date: Aug 2000** 06-09-2003, 7:26 AM

I made the mistake of running 87 octane in my boat a few times. I thought there was something wrong because the boat would lose power all of a sudden when pulling a rider. It would just drop about 100-200 rpm and I would have to give it more throttle to compensate. It was very annoying and I took the boat in for service thinking there was something wrong.

The techs could not duplicate the problem and even tried to blame it on too much weight in the boat causing it to fall off plane. About a month later I was looking in my manual and noticed it called for 89 octane. So I called a PCM rep and asked if the engine had a knock sensor. Sure enough it did and was detecting knock and retarding the timing before we could even hear any pinging.

The techs could not duplicate the problem because they were not putting the same load on the engine when they lake tested the boat.

Needless to say I run 89 now and they recommend it for good reason.

(whazzup) · (whazzup) **Join Date: Oct 2001** 06-09-2003, 8:12 AM

I'm sure the manufacturers reccommendation should be followed but I've heard some people that have used 87 octane and never had any problems. I guess its not worth the $1 or $2 extra to have addt'l problems.

cws_kahuna 06-09-2003, 9:06 AM

I used the lower grade gas once on a trip to Lake Mead. I mistakenly selected the 87 or what ever the low grade is in Vegas but I thought well I'll just use it. The boat ran bad the entire trip, but I still had a lot of fun. I have always used the High Octane 91/92 gas in my boat. Boats have a lot of stop & go, but not stop & go like a car where you slowly accelerate. Boat engines run really hard compared to a car engine, especially tow boats, with all the extra weight added, and pulling riders all day. I figure it's not gonna hurt anything to run the better fuel.

(greatdane) · (greatdane) **Join Date: Feb 2001** 06-09-2003, 9:22 AM

Use the lowest octane that does not ping.

It is a total farse that higher octane is doing your motor a favor unless the lower octane is running bad.

My 2000 VLX runs perfectly at sea level (delta elevation) with 87.

ridinhigh 06-09-2003, 9:40 AM

I have always used at least the minimum octane recommended by the manufacturer simply because when they calibrate the engines they use whatever octane they put in their documentation to the customer. I don't doubt that some engines you could probably get away with running lower octane but seems like a small price to pay for peace of mind.

(greatdane) · (greatdane) **Join Date: Feb 2001** 06-09-2003, 10:18 AM

Many car companies document higher octane requirements because their emission and performance look a tiny bit (a few percent) better. Thus, it helps sell the car.

Again, you are just wasting your money unless the engine is knocking. The notion that you are doing something special for your engine is a total farse. In fact, Exxon had to retract such claims in court a few years back.

(hatepwcs) · (hatepwcs) **Join Date: Mar 2002** 06-09-2003, 11:46 AM

My merc calls for 87, thats what I use. I've also heard some of the additives in the higher octane fuels can be corrosive to marine fuel lines. I hate when marinas don;t offer anything lower than 89 or worse 92. They know they got you.

(barry) · (barry) **Join Date: Apr 2002** 06-09-2003, 11:57 AM

Chris Neelley is always complaining.

B-

(troyl) · (troyl) **Join Date: Feb 2002** 06-09-2003, 12:08 PM

I have the same issues as Greg where i can feel the computer knocking down the power(timing) when i run cheap 87 octane gas. I still run 87 most of the time but it seems like some brands are worse than others. Arco 87 seems to be the real problem in my boat.

(wakeeater) · (wakeeater) **Join Date: May 2002** 06-09-2003, 5:01 PM

o yeah just remember american gas ratings minus 2 octane so 87 is actually 89(gota love gopednation)

(sn0w) · (sn0w) **Join Date: Jul 2002** 06-10-2003, 1:14 PM

I always put in 89 (canadian)

beth 06-10-2003, 8:43 PM

We JUST got a 03 SANTE and the PCM manual advises 87 octane. It states "The use of higher octane fuels in these engines, besides added operating costs, can cause temporary performance loss and is not recommended." We were VERY excited about being able to use cheaper gas. We had to put premium in the old boat for it to run well.

(Message edited by beth on June 10, 2003)

(eccpaint) · (eccpaint) **Join Date: Feb 2002** 06-10-2003, 9:48 PM

No problems with 87 octane in our 2000 Tige.

ridinhigh 06-11-2003, 5:44 AM

Does anybody else have the Excalibur engine? I could've swore I read that they recommended 89 octane but after reading what Beth H mentioned did I dream this up? I sure wouldn't mind saving a couple bucks using 87 instead of 89.

sxr 06-12-2003, 1:57 AM

91 here in Aus...thats the basic unleaded here.

I can't believe US has crap fuel.

(vortech347) · (vortech347) **Join Date: Aug 2000** 06-12-2003, 6:12 AM

Ray,

Octane rating has nothing to do with the quality of the fuel. It is only a rating to show the fuels resistance to detonation and is achieved by adding chemicals like toluene to the fuel to achieve a certain octane rating.

All 3 grades of fuel sold here in the US start out as the same fuel. Then the companies add their own blend of additives to create the octane rating and add in their detergent package.

If your vehicle runs properly on 87 octane then you should run 87. 87 octane is just as good as 93 octane from the same maker and will make more power and get better mileage in a vehicle designed to run on it.

The reason some engines require higher octane fuel is because they have been designed with more compression, more advanced timing, or have a turbo or supercharger and need the added resistance to detonation. In those instances their more aggressive tune makes a lot more power than a less agressive tune that runs on lower octane fuel.

The oil companies do market higher octane fuels as "higher grade" fuels because they make more profit off of them. It doesn't cost them 10-20 cents more per gallon to make 89 and 93 octane so they want you to buy it thinking your doing your engine a favor. It's not lieing to say higher grade but it is a marketing gimick.

Lastly, do not buy fuel at bargain stores. Stick to major brands at stores that see a lot of traffic. The bargain stores like Costco, Sam's, etc. buy the cheap fuel that just barely passes the grade as gasoline. That is why they can sell it cheaper. It only makes a couple dollars per fillup difference but can save you the headaches of a damaged fuel system that is not covered under any manufacturers warranty.

samcdog 06-12-2003, 6:57 AM

Ridin high - I have the excalibur and it recommends 87 octane. It is definitely nice to be able to use the cheap gas.

(matt_h) · (matt_h) **Join Date: Jun 2002** 06-12-2003, 7:49 AM

Not Cheap! , Less expensive

(bob) · (bob) **Join Date: Feb 2001** 06-13-2003, 2:22 AM

I will repeat this: "my boat recommends 89 and i think many of the newer ib/v drives also do, read your manual since running with an engine pinging/knocking can lead to its early demise". Many people are correct in that if an engine does not need the higher octane then using it will give you no benefit BUT if your manual says 89 then it WAS designed or through testing found to better operate on the higher octane. Chances are with all the ambient noise in a boat you will not hear it pinging until it is too late, burned or holed piston. We are operating high horsepower engines so it makes sense that they have advanced the timing and rasied the compression a bit for that horsepower to be available to us.

(sid7) · (sid7) **Join Date: Mar 2003** 06-13-2003, 5:59 AM

i use 93 octane if not my motor spudders some on my I/O when i turn it off. besides i have noticed it runs better over all.

(csquared) · (csquared) **Join Date: Jan 2002** 06-13-2003, 9:54 AM

If your boat is newer and injected, the use of a lower octane fuel is not going to cause any damage, only a loss of performace. The knock sensors will retard timing long before you do damage or hear the knocking. Your ability to use lower octane gas is going to depend on the quality of the fuel, brand, season, altitude, condition of the motor and driving style.

Try it...and run a bottle of chevron techron fuel system cleaner through the tank twice a year. Chevron is superior to most of the other cleaners for a number of reasons and greatly helps in keeping octane requirements low.