On 21 Oct 1998, Peter Cebalo wrote:
> The oil companies offer an
> additive - 'valvemaster'.
> All I can say is - spend your money on hardened valve seats.
Sodium or potassium based additives, like for instance the DuPont
Valvemaster, *does* have a well documented effect on valve seat recession.
Test results I've seen suggests protection that is significantly better
than for low-lead gasoline (0.15g per liter).
> Still the performance difference is noticeable and now
> we have to put up with sooty spark plugs that need cleaning every few
> thousand miles and engines that
> pink badly under load.
That has not really been my experience with unleaded (we use RON 98 here,
BTW). In Norway we've had LRG (lead replacement gasoline, i.e. unleaded
containing potassium-based valve recession additives) for many years, and
trying out leaded 4-star in UK this summer, I can't say I noticed any real
difference.
In general, unleaded gasoline should have less problems with sparc plug
fouling than do leaded, due to formation of lead-based deposits. If your
plugs are outright sooting, a check of the mixture and CO levels, as well
as ignition system, would definitely be required (and quickly be
paid for by decrease in consumption).
Of course, unleaded gasoline comes in various flavors, and it might of
course be that European unleaded is of another (and more favorable)
composition that the one you are using.
> about US$110 for a Spitfire and
> US$150 for a TR )
That sort of money would buy a lot of additives that are scientifically
documented to work. At least, I know where I would have spent my money ;-)
If you really need an octane increase, toluene is an efficient additive.
Egil
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