I had it done one time. Actually, they didn't ask me if I wanted it done. They just did the fuel injector treatment, which kind of made me mad. But it didn't hurt the truck. I think it did run a little bit better, but I didn't notice a huge difference.
I have a friend who just bought a new Sienna and she wants to know if rust proofing the Toyota actually is worth the money? Does it actually help to keep the vehicle rust proof?