Lead replacement additive

[accord83]

When I run straight octane booster turns my plugs brown, but they've never fouled.

[caprimk1v4]

No, its only if you really go over the top with the dilution ratio, it will foul the plugs, not at normal levels. 

[chinkamon]

I can't remember but with the castrol One I'm sure I used to put a bit in every time I filled up, if I put 20 litre in I put 20ml of castrol in or there abouts?