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Valvemaster is usually added at 1
millilitre per litre of fuel for most normal applications. Dick
Bugala from Shell (retired) said that for hard use such as full
power hill climbs or towing a heavy trailer (where exhaust gas
temperatures are much higher) 1.5 millilitres would provide a
good safety margin. I typically use a bit too much, 20% extra,
we do enjoy our car at any appropriate opportunity such as
mountain driving; Cs are good at this.
The History
of Valvemaster: This product was developed by Du Pont in the
1930’s to act as a de-carbonising additive for US V8’s etc.
which required regular de-carbonising, necessary with the poor
ash laden fuels of the time.
Later in
the 1960’s when fuel was heavily leaded and plug fouling was a
big problem Shell advertised SHELL with ICA (Ignition Control
Additive) as a marketing ploy. This ICA was Valvemaster, (I
changed from BP to Shell about this time and have used it ever
since) and is probably why Shell use Valvemaster, as they know a
lot about the product.
Shell
Optimax: One of the claimed advantages of this fuel is that it
has additives added to keep the injectors clean and to dissolve
the carbon build up on the back of the Inlet valves of 4 valve
heads. This build up is caused by the injector spray pattern and
carbon build up starts to affect fuel economy and performance
with time. It is often recommended to have the injectors cleaned
and also the inlet ports and the back of the valves at about
80,000 km, to restore original performance on modern engines.
What
advantage is the above to MG owners? With the combined effect
of Optimax and Valvemaster dissolving carbon, the fuel keeps the
engine clean and in our car where the head has been on for
46,000 miles since reassembly in 1986 it has effectively
de-carbonised the engine. When I first used the
Optimax/Valvemaster combination the oil came out looking very
black and with each oil change it got slightly lighter in
colour; the oil now looks as it always did when new.
Oil
consumption has decreased with time so the pistons ring lands
and rings must be clean. When I had the huge lump of “Best
British Cast Iron” out a couple of years ago to change the
clutch cover, I had a good look inside the ports and was
surprised to see shiny bronze inlet valve guides, clean inlet
ports and from what I could see into the combustion chambers it
all looked very good.
Our car has
now run for 20,000 miles with Optimax and Valvemaster and even
with a less than optimised distributor mechanical advance
performs well. The car is not happy when it is fed any 96RON
fuels, possibly because I am using NGK BP7ES plugs (N7Y
equivalent).
Before Optimax and BP Ultimate these would foul on
low load/traffic conditions. Bosch W6DC & BP6ES (N9Y equivalent)
were used successfully for years as the Downton supplied N7Y
fouled from day one, possibly from the high lead component of Av
Gas 100/130. With 9.5:1 CR I had to use BP100 or Av Gas 100/130,
this is why the compression was reduced to make long trips
possible.
Bruce Ibbotson. Member #600.
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