Subject: Re: Lead replacement fuel additives. Necessary?
Yes, as Laurence says, I have always used the tappet clearance check as an indication whether or not one is getting valve seat recession. No problems over the years so far with ordinary road use.
However I think that ethanol in petrol is a far greater problem. My advice (for what it is worth) is to minimise the use of any fuel with ethanol in it. For some years I have only used 97 or 98 octane (usually Shell or BP) in my old cars. Inconvenient (and expensive) I realise but I think it is worth the trouble.