Fuel premium vs regular ?

[artdf175]

Is there any disadvantage to running a tank of premium through the engine periodically ?
Other than cost? Actually premium at the moment is cheaper than the regular last summer. thinking is premium might have more additives than regular but could be convinced otherwise
Anybody with thoughts on the subject?
Art

[Moonlighter]

Hi art

Of course there are different fuel grades in different countries, but my Suzuki mechanic recommends a tank of premium once every 6 months for just the sorts of reasons you mentioned - premium has more additives, cleans injectors, fuel system so thats what he recommends. He says there is nothing wrong with using it all the time, either.

I just did it a while ago and it seems to run thr nicely, and slightly more economical.

Cheers

[artdf175]

thanks for the info
it just kind of made sense
at somepoint.. I will let you know how it works
middle of winter here in the N.W.
Art

[Moonlighter]

thanks for the info
it just kind of made sense
at somepoint.. I will let you know how it works
middle of winter here in the N.W.
Art

All good!

Its middle of summer here, not the best boating weather though as it is often windy. Temps 30 C today but had a couple of days last week where it got close to 40 C (104F) which had us reaching for a beer, or twenty!

Grant

[artdf175]

Grant.. Mid 80's is a great temp..
we are running between 0 C and 1 C here in the mornings and 5C to 6C for highs.. so it is a bit nippy..
I will get those photos to you
is the email address I saw on the other thread the correct one?
and Thanks

art..

[szkfxer]

Actually running higher grade gas makes no sense at all.
If motor is designed for the regular gas (i.e. has low compression ratio) - higher grade actually can lower the motor's life expectancy.
If you want to clean injectors/carburetor and fuel lines - using proper fuel additives is far better solution.
Higher grade gas will not get rid of water or clean anything.

[Moonlighter]

Actually running higher grade gas makes no sense at all.
If motor is designed for the regular gas (i.e. has low compression ratio) - higher grade actually can lower the motor's life expectancy.
If you want to clean injectors/carburetor and fuel lines - using proper fuel additives is far better solution.
Higher grade gas will not get rid of water or clean anything.

That, with respect, is all rubbish.

[Harper]

That, with respect, is all rubbish.

Come now, Grant, calling someone's opinion rubbish isn't exactly respectful, no matter how you try and sugar-coat it. I might be wrong but, based on a little reading between the lines (or letters, in this case), szkfxer might just be a Suzuki mechanic, and if so, then his opinion is just as valid as that of your Suzuki mechanic. For that matter, my opinion is just as valid as yours or that of your mechanic.

I already told Art, in answer to a private email to me, that I didn't think it would do any good to run any premium gas, since in this country, 87 octane and 91 octane, distributed by any major refiner, both have the same amounts of detergent, same additives, same fuel system cleaners, etc. The only difference is the octane, and 91 octane has a slightly slower burn than 87 octane, so that it won't knock in higher compression engines. And since our outboards are tuned for 87 octane, they will run more efficiently on the lower octane. The best advice that I could give Art, and that I would offer to anyone else, is to use non-ethanol gas if you can find it. As you pointed out, it might be a bit different in Oz, and if you and your mechanic over there agree that there's any difference in the grades of gasoline other than octane, it might just benefit you to run the occasional tank of premium. Over here, I would consider it a waste of my money. But I don't tell anyone else how to spend theirs.

[szkfxer]

That, with respect, is all rubbish.

Well, it may look like one but on contrary to a popular believe it is true.
You do not want to fill-up your car with high octane fuel, right? why?
'Cause it'll burn your engines' valves and kill spark plugs fast. True?
For the same reason you do not want to use higher octane gas in your outboard.
Compression ratio is the main guide for the fuel octane number. Increase the ratio - get a higher octane. Lower the ratio - lower an octane number.
BS sold by mechanics on basis they have never learned the engine maintenance for the long run. They want you to come back soon!
I did repair many engines in my life. Built just as many.

Have seen it all and never a good thing that came out of using a higher octane on a low compression engines.
With respect to your opinion - you must have seen too many commercials without giving it much of a thought - the outcome:

That, with respect, is all rubbish.

[Harper]

You do not want to fill-up your car with high octane fuel, right? why?
'Cause it'll burn your engines' valves and kill spark plugs fast. True?

Now I can respectfully disagree with that statement.

In 50+ years of working on gasoline engines, I have never once seen any damage directly attributable to burning premium gas in an engine designed to run on regular.

[szkfxer]

..The best advice that I could give Art, and that I would offer to anyone else, is to use non-ethanol gas if you can find it...

Where do I sign the paper Harper? 100% with you on that!
Ethanol is not good at all to the engine, especially for outboards. That's the reason I have mentioned fuel additives. Not just any additives.
It is hard to choose based on many commercials out in a open. Most of them are totally based on marketing (read further BS).
Back in the 80's when I was in university we did tests on oils, additives etc..
Guess what brands were the least performing? The ones that were mostly advertised.
Since then I took it as a rule of thumb - check the commercials and never buy any brands they advertise.

[szkfxer]

Now I can respectfully disagree with that statement.

In 50+ years of working on gasoline engines, I have never once seen any damage directly attributable to burning premium gas in an engine designed to run on regular.

I did. Take the race cars, racing hydroplane boats - I did work on many of those. Main issue - burnt valves. As much as quarter of valve was burnt. It looked like blow-torch was used.
If valve is not adjusted properly or lifter is stuck - fuel burns thru valve very fast. Which is not true on a low octane motors.
Go figure.

[Harper]

I did. Take the race cars, racing hydroplane boats - I did work on many of those. Main issue - burnt valves. As much as quarter of valve was burnt. It looked like blow-torch was used.
If valve is not adjusted properly or lifter is stuck - fuel burns thru valve very fast. Which is not true on a low octane motors.
Go figure.

No, the reason for burnt valves is always either 1) too low an octane, thus detonation, or 2) improperly adjusted valve clearances, resulting in little or no dwell time on the valve seat. It is not possible for a slower burning (in microseconds) fuel to burn a properly adjusted valve, or to cause any greater burning of spark plug electrodes. And to compare race engines, be they land or marine, to engines designed for everyday use is comparing apples to oranges. Race engines are only built for the short haul, and are designed with the idea that they must be rebuilt every few runs. Designs of race engines would be considered a fault in engines designed for the consumer.

[szkfxer]

No, the reason for burnt valves is always either 1) too low an octane, thus detonation

Detonation kills the piston, piston rod, crankshaft and all things in-between, not the valves.

2) improperly adjusted valve clearances, resulting in little or no dwell time on the valve seat.

agreed

[Harper]

Detonation will burn valve heads, will burn spark plug electrodes, melt spark plug ceramics, will blow holes in piston tops, will bend or break connecting rods, will ruin piston pins and rod bearings, and will melt all manners of components in the combustion chamber.

Let's face it, when you speak of race engines, you are talking about engines that run on very high octane fuel mixtures, often high in alcohol (methanol in this case) or pure alky. They are running with extremely advanced ignition timing, running well into the detonation region of tune, with very high cam overlap profiles and long open valve durations, running at high RPMs at full throttle 99% of the time. They are expected to burn up.

Your comparisons here with our everyday Suzuki outboards, designed, built, and tuned for reliability and longevity, are becoming tiresome. You are coming very close to making me feel that I should apologize to Grant for getting on him about calling your opinion rubbish. Only difference is that I would do it without any feigned respect. In any case, I'm done with this conversation.

If anybody wishes to use premium gasoline in your everyday, plain-Jane Suzuki outboard, please do so. It might or might not help, but it sure won't hurt.