I have used seafoam in my (and my daughter's) present and past two vehicles. I have never had any problems from its use, but plenty of benefits. The only vehicle I have had to replace an O2 sensor on is my current car, a 1994 Accord with 215k miles on it. I seriously doubt it had anything to do with Seafoam, just miles and time. I have used it in all types of applications, from go-carts to mowers to trucks and cars. It is also available as a spray-can product which makes the pcv valve hose and other similar uses much easier.