Mike Thompson <miket@rio.edu> wrote
> Hello All,
> Not that I have an oil burner But I have wondered...
>
> Would an engine that burns a little oil need a lead additive to save the
> valve seats of an old head?
> Or would the oil being drawn by way of the valve seals or rings be
> enough to "lubricate" the seats?
>
> Just thought I would throw that out to the list.
> Cheers,
> Mike Thompson
The oil will burn as soon as it gets down there and there are no benefits
from so-called "lubrication" to delay valve seat recession with leaded gas.
When I restored my TR3A, I did the engine too. I kept it very original
(1991 cc), but in 1990 just when the car was finished, Canada banned leaded
gas. I decided not to pull the perfectly restored head to put in exhaust
valve seats. I decided to test how far I could drive with unleaded, no
exhaust valve seat inserts and no lead additives. I didn't believe in Lead
Additives any more than the proverbial "snake oil" claims. And I still
don't.
Starting about 35,000 miles later (1997), I found I was re-adjusting the
exhaust valve clearances about 0.008" every 3,000 miles. At 43,000 miles, I
pulled the head and had inserts put in for the exhaust valves, 8 new valves
and 8 new valve guides. The edges of the exhaust valves were razor sharp.
All this time, I had been getting about 600 miles to a quart of 20W50 engine
oil (Castrol).
Over the last two summers, I have driven 17,000 miles and I have not needed
to readjust the valve clearances more than 0.001" every 5,000 miles. And I
still get 600 miles to a quart of Castrol.
Don Elliott, Original Owner, 1958 TR3A, TS 27489 LO
Montreal, Canada
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