Chevron Techron additive concentrate doesn't have lead or aggressive solvent in it. I think the solvent they use in the concentrate is similar to low aromatic solvent.
It has an organic detergent/dispersant which is slightly different from the additive used by other additive suppliers. This additive is strong, it'll clean injectors if added to just one tank.
However Chevron do recommend not to use too much of the concentrate, I think its no more than 3 or 4 bottles per oil change. This is because some of the additive does get down into the crankcase, and if there is too much it will affect the oil. I think it might make the oil thicken.
But I've used Techron additive concentrate regularly for over 300,000 km (200,000 miles) in a number of vehicles and had no trouble, and never noticed elevated lead levels when doing UOA.
[ June 10, 2004, 05:12 PM: Message edited by: SteveS ]