Does it do any harm adding a additive even if your heads ben done

[Mercmancdi]

Was asked today / if you did not know if your minor head was ever done for modern petrol would it do any harm to use an additive anyway.
I advised him it should do no harm but I know more about newer engines that the older ones. Is there a simple way to tell if his head was done .

[simmitc]

It probably depends on what the additive is. If referring to something like Castrol Valvemaster as a lead replacement, then no harm at all in using it. If some of the snake oil miracle cures, then don't waste the money. The modification for using unleaded fuel is hardened valve seats, and the only way to know if they have been fitted is by inspection after removing the head - or having the receipt.

[Mercmancdi]

I mailed him he bought Wynn's Specialist E10 Petrol Fuel Protector Makes E10 Safe For All Petrol Engines.This should do him no harm either way shouldn’t it .
Thanks