What additive do you use?

I'm a big fan of fuel, tranny, and oil additives. I was just wonderin what everyone here was using in theirs.
I have two fav. brands.
Z-Max Additives and Lucas Additives, both of which are killer.
Haven't tried many octane boosters-other than lucas.
So if you got a specific brand that really kicks azz post it. I could use a few more ponies. :cool:

I've used a product called Prolong before. I haven't used it in the ls1 yet, but when it gets a lot of miles, i will.
I put it in the previous engine and tranny though. At 85K miles, the tranny was slipping and stuttering, after some trans Prolong additive, it worked perfectly for about another 80K, put some more in , and it lasted until the truck had 210K miles.
As for the engine, I put that in every 5th oil change and it made the engine run smooth and never missed a beat, except when i blew a head gasket, doh. water pump dumped on me.

For the current ls1, i just use 5w mobile syn.

later,

allen