yea i use it all the time and love it. Get a bottle throw 1/3 in the crankcase 1/3 in the intake and 1/3 in the gas tank and it will increase gas mileage without a doubt. i went from 18mpg when I first got the car w/o seafoam to 26mpg w/ seafoam. I have never had any problems but my car only has 75k on it so I really don't know the effects on a high mileage car. It is a great cleaner but it has some harsh detergents in it so it definetly could effect seals and what not on older cars i would imagine.