BEST GAS?

[DARK30]

WHATS THE BEST GAS TO USE IN AN OLDER (1977) MERC 20 HP MOTOR? DOES HIGH OCTANE MAKE A DIFFERANCE? ALSO WHATS THE BEST OIL TO GAS RATIO FOR THAT MOTOR?
LAST YEAR UP AT THE LAKE I WAS TOLD TO USE A CERTAIN KIND OF GAS BUT I DON'T RECALL WHAT WAS DIFFERENT ABOUT IT NOW.
THANKS!

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cast,cast,cast,cast......

[Valv]

Dark30, if you can buy higher octane (eg. 92) it would be better. In Faribault I found a station that sells "Racing Gasoline" which is leaded gas, but price scares you away ($ 7 or $ 8 per gallon). Just use 50:1 mix ratio and be sure your carbs are set more on the rich side than lean, especially at high RPM.

[Bodyman]

I was told to use premium unleaded in my old evinrude 50/1 and use a lead additive if you can't find regular leaded gas. Being a 77 I'm not sure if that motor set up for leaded or unleaded gas.

[TUMBLEWEED]

Unleaded vs Leaded gas is mute.With the advancements of the PREMIUM two-stroke oils,it doesn't really matter with what you go with,as long as its of a higher octane
value,like a premium grade.I would stay away from too much use of those racing fuels on an older motor too.Costly,and really an overkill
in most cases anyway,plus a good way to fry a cylinder.What is more important for older units,is too use gas that doesn't have that ethanol dump in it.This stuff is hell on seals and what not.There are some places that do sell non blended fuels,though they can be tough to find.Call around.Also always use a PREMIUM oil and not some cheap junk on sale.
Forgot to talk about mixtures.Get your model
and year,and give your local shop a call for
how much oil to use.Always try to be precise
when mixing too.

[This message has been edited by TUMBLEWEED (edited 07-24-2001).]

[delmuts]

i agree on the staying away from the gas and alcohol mix! not good for outboards. the racing gas would be a waste of money. i do try to get a little higher octane if possible, but was told to run reg gas , but buy good oil. and remember to keep it fresh. if it sits for very long put some stabilizer it just in case.

[DARK30]

THANKS FOR THE HELP GUYS, I CALLED UP TO WHERE I HAD THE BOAT TUNED LAST SUMMER AND HE SAID I SHOULD STICK WITH STRAIGHT GAS WITHOUT ETHONOL (LIKE YOU SAID). I GUESS YOU HAVE TO LOOK AROUND FOR IT IF YOU WANT A HIGH OCTANE WITHOUT ETHONOL. NOW...IS THE LEAD ADDITIVE AN IMPORTANT THING TO ADD?
WET NETS!

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cast,cast,cast,cast......

[TUMBLEWEED]

Nope, not needed as long as you use the PREMIUM grade of two-stroke oil.The lead was used for upper lubrication like the valves etc.The newer oils have been improved to do a better job of this now.The use of a fuel stabilizer is also an excellant suggestion.
I use the one called "STABIL"

[Bodyman]

I know an old OMC mech that would tell you different about not using the lead additive in motors that are made for leaded gasoline. He went as far as having copies of the ratio additve to gal printed up to hand to his customers so they did it right. He said many of the older motors he worked on were in there because the additive wasn't used. I believed him and used it regularly and didn't have a problem on my 1955 15hp evinrude. She ran like a top.

[Guest]

Just a thought, If I remember correctly lead was added to gas to reduce Valve knock and Wear. 2 stroke motors (most older outboards)don't have valves for intake and exhaust. Ergo, if there are no valves to lubricate why do you need lead in your gas to lubricate valves?