From: utzoo!watmath!watcgl!dmmartindale
Newsgroups: net.misc
Title: Re: Regular vs Unleaded Gas
Article-I.D.: watcgl.185
Posted: Fri Feb 11 02:03:18 1983
Received: Fri Feb 11 07:14:50 1983
References: utcsrgv.998

There is no metallic lead in "leaded" gasoline.  The octane-increasing
additive is tetraethyl lead.  I don't know what it turns into during
combustion, but I would expect a lead oxide of some sort.  Whatever it is,
it tends to deposit on things, and provides lubrication for the valves
and valve seats.  Older engines need this; newer ones use better materials
in the valves and seats and can withstand running with no help from the lead
byproducts.  Presumably they will still last longer if the lead is around.
It can be a mixed blessing, though - lead deposits on the valve stems
can cut down gas flow through the engine, and sparkplugs can become
lead-fouled (a very common occurrence in aircraft burning 100/130 octane
fuel, which has lots of lead in it).