In response to a recent thread, I wrote to the customer service departments
of several gasoline companies. So far only Chevron (No financial interest,
Yadda Yadda Yadda) has responded. I guess unleaded is OK under the
"right" conditions. I'm pessimistic so I guess I'll go for the hardened seats
just to be sure.
Here's their response:-
"I am not aware of any inherent chemical properties of current unleaded
gasoline that would prevent valve seat sink under the "right" service
conditions in cars with valve seats that are not hardened. Nor do I
believe that many unleaded gasolines contain an additive to compensate
for the lack of lead. Chevron's unleaded gasolines don't. However, it
is Chevron's belief that using unleaded gasoline in older cars with
valve seats that are not hardened does not present a problem for most
types of service. This is should be particularly true for the light
service most antique sports cars see. Valve seat sink only becomes a
risk at higher than normal engine temperatures generated by operation at
sustained high speeds and/or loads. Please see our technical bulletin
on the subject at www.chevron.com/chevron_root/prodserv/index.html.
Happy driving."
Do with it as you will
Andy
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