Quote:
Originally Posted by Loganvilledude
I just looked at one of my operator manuals for the 1000-1650 Tractors,
"This engine is designed to operate on leaded gasoline with a 93 minimum octane rating or on unleaded gasoline with a 91 minimum octane rating. It goes on to say that the unleaded gas will increase spark plug and valve life, maintain engine performance longer and reduce rust and corrosion of the engine while stored." Publication 8-77.
The Kohler service manual I have which covers engines K91-K341 suggests unleaded gas 87 octane and higher. It goes on to say using leaded gas will require more frequent service on the cylinder head. Publication 4/90
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LoganvilleDude: Hum . . .
It seems the IH engineers and the Kohler engineers were on two different wavelengths.
I remember owning a 1973 Pontiac which had a filler neck for leaded gas, but hardened valve seats for unleaded gas. The seats were hardened --no inserts; and the owner's manual discussed the fact that unleaded gas would not DAMAGE the engine. I've heard of engines requiring service to install new valve seats to run the unleaded gas. At the time, the loss of lead in the gas was generally viewed as a LOSS, not a gain.
Personally, I run 93 octane simply because it is cleaner. I have never heard of IH recommending it. In fact, I've been shouted down in other forums because it was viewed as overkill.
The "scientists" will tell you that premium grade fuel is designed for higher compression engines and actually burns slower, the thought being that 87 octane is "better" for the relatively low compression Kohler engines. Their argument is buttressed by the contention that the slower burning fuel will result in greater carbon buildup in the combustion chamber.
But I'm not convinced. I feel that the more highly refined fuel will yield a more CONSISTENT burn. Even the "regular" guys admit to using additives, some of which function to increase the fuel's octane rating.
As far as the storage of fuel goes, I've always thought that premium held up better than regular, but the fact is, all the discussion of 87 octane versus 93 octane ignores an even bigger fuel factor which has developed since the 1970's --the use of ethanol (alcohol) in gasoline in concentrations approaching and equal to 10% by volume. The alcohol content destroys fuel lines, gums up carburetors, attracts water and generally wrecks havoc with fuel systems, and makes it almost impossible to effectively store fuel from one season to the next.
Again, I've gone to Premium (93 octane) for my air-cooled engines and I add Marvel Mystery Oil or Lucas Gasoline Treatment or Sea Foam (if I suspect gumming up), and I try to run the engine dry at the end of the season. Since I've been doing this, I have not had to rebuild a carburetor on any of my equipment (knock on wood).
