Hi Jason,
So if someone brings a vehicle under manufacturers warantte to you, you would invalidate the warantee by putting additive in?

Here is an extract from the first handbook I laid my hands on:

"Oil to the correct specification contains additives
which disperse the corrosive acids formed by
combustion and prevent the formation of sludge
which can block the oil ways. Additional oil additives or flushes should not be used."

Good luck if it's working well for you, I'm just interested. I do use Forte products & happy when I use them, it's just I wouldn't want them used in my car without giving my permission first.

Regards
Steve