Chuck Vandergraaf writes
>A second question concerns the use of unleaded gas in an engine that was
>designed for leaded gas. I've been led (no pun intended) to believe
>that lead (Pb) in gas hardens the valves and that the replacement,
>manganese (Mn), will eventually lead to problems.
The issue is that the valve seats on older engines are not hardened. Lead
in the fuel forms a protective layer, especially in the exhaust port. Such
an engine will suffer valve seat wear when run on unleaded fuel. I am not
clear on the extent of the wear, or on the influence of substitute
additives.
98 Octane leaded fuel is still available in the UK as it was only in 1988 (I
think) that cars had to be able to run on 95Octane unleaded and only in
1993 that CATs became compulsory on new cars. Advice given by some
manufacturers (e.g. GM) for those who wished to change was to run one
tankful leaded in four so maybe an occasional treatment would be enough.
Dave Vodden
1992 Plus 4 4 seater
Hampshire UK.
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