Lead Replacement Additive

Hi all,
Quick question, is there a particular additive you recommend to prevent exhuast valve pitting. I have a Lister AK and intend to run primarily on paraffin, however, during the 'tweeking' stage I will just be running on a carb of petrol each time. Also, although I have plenty of paraffin, is there any reason I shouldn't run the engine on petrol only for longer periods?
Thanks,
Stuart

Leade additive is not required as ours engines were built before lead was added to fuel, you can run the engine on petrol or paraffin, to run properly on paraffin the engine has to be up to temperature which is why you start it on petrol and then change over, for rallying use petrol is cheaper than paraffin so engines generally are run on petrol.
There are very few engines designed to run on paraffin from the start, most have a heat source to vapourise the paraffin first, there is one engine designed to start directly but as I type this I cant remember the maker.
Remembered the make its a Bristol Wagon and Carriage Works Co Victoria engine.
Maryalice

Thanks Maryalice,
I always thought all old engines required addutive when using unleaded fuel, you learn something new everyday.
Stuart.

Martin,
The Kerosene version of the 'Victoria' starts on petrol from a small tank attached to the main fuel tank. The company were experimenting with a 'start from cold' when  Leeds Forge Co took them over in 1922 , closed them, and concentrated on railway carriages. A well-known Victiria owner has a SFC engine which I believe is experimental and uses a wick and a flame burner to heat the kero. Very dangerous in a barn with hay, straw etc!
Eric

Thanks Craniun,
I've always thought they ran on paraffin alone, somebody has been telling me porkies.

Maryalice