My engine is 351 Cleveland and never used any additional additives. I always use premium fuel 99 octane E5. The seats valves on American heads have been hardened since the early 70's. I believe even Rovers V8 have hardened seat valves from the 1980's.
Ethanol is a rubber eater and is awful stuff on your skin. It eats rubber gloves and even rubber fuel pipe after 3 years!
My spark plugs look super clean and I am happy with the fuel mixture which has been adjusted on a rolling road. AFR was 12.5 which is a bit rich.
Quote from: JON1D on Mar 09, 2026, 12:05 PMMy engine is 351 Cleveland and never used any additional additives. I always use premium fuel 99 octane E5. The seats valves on American heads have been hardened since the early 70's. I believe even Rovers V8 have hardened seat valves from the 1980's.
Ethanol is a rubber eater and is awful stuff on your skin. It eats rubber gloves and even rubber fuel pipe after 3 years!
My spark plugs look super clean and I am happy with the fuel mixture which has been adjusted on a rolling road. AFR was 12.5 which is a bit rich.
Hi John ,
Thanks for your reply,
You are correct with regards to harden valve seats on the old RV 8, as mentioned I've always used the Castol valve master plus after the dreaded four star leaded disappeared.
My thoughts it being a bit of belt & braces until things ironed out with unleaded petrol, initially I just used the standard unleaded but stopped doing so when the petrol company's started introducing the nasty Ezzz into to
the process, no the Ezzz are not good .
With regards to shell as far as I know there should be zero ethanol in the premium stuff although they state five
percent ethanol on the pump ?
This is to cover all eventualities, therefore no comebacks me thinks .
Currently I use either shell or the Esso and have had no noticeable issues to date, plugs show a grey burn and
if I have to hit the accelerator to get over the hump in my garage I get a bit of black soot, due to Holley accelerator pump .
Ultimately I may not need the additive but old habits die hard and the Castrol valve master plus use to give a bit of octain boost although I am not sure these days, the Millar's states it gives about two points ?
Chris.
Quote from: Chris on Mar 10, 2026, 07:15 PMWith regards to shell as far as I know there should be zero ethanol in the premium stuff although they state five percent ethanol on the pump ?
Not anymore, unfortunately, it contains 2.5% ethanol: https://www.youtube.com/watch?v=UBkBa_rEj7w