>
>I have found several different brands of lead substitute and purchased STP's
>version of "lead substitute" fuel additive. Unlike my diet coke, the product
>label doesn't give any clue as to the ingredients or nutritional value for my
>car.
>
>Does anyone know what's in this stuff?
>
Tetraethyl lead was the primary octane booster for years. The lead also
helped the valves by coating them and the seats (I believe). I cannot say
exactly what compound is in use now for the "lead substitute" except that it
is usually a phosphate based chemical. As a chemist, I usually like to see
the actual ingredients listed so I can buy the chemical direct as its much
cheaper. For example, gas line antifreeze is usually methanol in a higher
priced container.
>
>Will it really save my valves? Does it really take the place of good old
>(virtually unavailable) lead?
>
Only time will tell. Perhaps a long time mechanic out there can make a
judgement call on this.
>Also, in my part of New Jersey, I have found one Sunoco station that sells
>their 100 octane fuel. It's a long trip out of my way and I'm wondering if
>it's worth the trouble.
>
Is this aviation fuel? The question still comes to what the octane booster
is. Is it the good stuff (tetraethy lead)? Or is it the newer compounds
including alcohols or MTBE? The downside to these oxygenates is their
greater tendency to vapor lock in warm weather. Either way, a higher octane
rating would probably not help your car more and it would be false economy
if you went straight 100 0ctane. I would blend it with a cheaper low octane
fuel to keep it in the low nineties.
High octane fuel is scarce here in Montana. But I blend various chemicals to
enhance the octane level. Usually though, my BGT does not seem to mind the
unleaded at 88. Some day I will most likely due a valve job, and then I will
convert the engine to unleaded. Any one else do this to their satsfaction?
David Councill
environmental chemist/consultant
dcouncil@imt.net
71 MGBGT
74 Toyota Landcruiser
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