Vauxhall sold me a set of 9195109 plugs for my LPG Astra. I believe they're supposed to sell me a grade cooler than those for petrol cars, however it'd not surprise me to find out these are standard petrol ones.

If they are LPG spec, are they OK in a petrol engine? If they're not LPG specific then I have nothing to worry about passing them on (all unused/fitted) to another Z16XE owner.