Who is still using lead substitutes?

[68gmsee]

If you are, what brand are you all using? I have a buddy who said he is having trouble finding it.

I haven't used any on my trucks since a machinist told me he had an old truck and never used lead substitutes. He said he drove the truck daily and had done so for years. Then he told me to wait until I started having problems and then bring the heads in. Made sense to me...