Dual-fuel conundrum

EVERY engine has valve recession, whether running on petrol, LPG or your grandma's bath water, but it happens at a faster rate on engines running on LPG. Your engine will have some valve recession, and switching to LPG will accelerate the wear. You could have to rebuild the heads sooner than you might if you stuck with petrol. The way around the problem with LPG is to fit a dual-fuel system and regularly run the engine on petrol to lubricate the valves and valve seats with lead, as happens when it runs on petrol alone. If you follow a routine of using petrol, say for an hour or two a week, you shouldn't have any problem. Upper-cylinder lubricants are available that protect the valves and valve seats from wear.