Join the Car Talk Community!

Discussion Rules

Welcome to the Car Talk Community!

Want to ask a question or join the discussion? Great! Join now.

Sign In Register

Fuel additives how often should you use them

I am planning to start using seafoam in my gas and oil ,how often should you a add it an how much.The label isn't to clear about it.


  • edited June 2010
    Why are you planning to use an additive? Are you having a problem? Frankly few cars need or will benefit from additives.

    That said, I would suggest starting by reading the car's manual to see what it may say and second try reading the instructions on the can.

    I generally use one bottle of a diesel additive to my VW diesel every year, at the beginning of winter to provide some anti-gel to prevent problems if we get a early cold spell. In over 45 years of driving, that is the only regular use a additives I have used and I have never had a problem that could have been eliminated or reduced by any additive I know of.

    Modern cars, oils fuels etc. seldom need special help.
  • edited June 2010
    As Joseph stated, modern cars, oils, fuels, etc, seldom need special help.

    Unless you have a specific problem that you're trying to get an additive to address, wouldn't you rather not waste your money?
  • edited June 2010
    I add a can of Seafoam or Chevron Techron once a year or so on my cars and trucks as preventative maintenance. My rule of thumb is to add roughly 1 oz of additive per gallon of fuel.

    Ed B.
  • edited June 2010
    I do the same about every 6 months. I have no idea if it does any good, but it doesn't hurt at that frequency.

    If you were to call the folks at SeaFoam they'd tell you to use it as much as you want (not surprisingly).
  • edited June 2010
    Ijust bought my car an when I changed the air filter there was a lot of black stuff in the throttle body an thought Ineeded to try an clean the rest of the motor out.Idid clean the throttle body out an it definitely helped.
  • edited June 2010
    Definitely helped WHAT?

    The throttle body on almost all cars is dirty to some extent. The dirt is only a problem if it makes the throttle stick or causes some other driveability problem.

    So what did cleaning it help?
  • edited June 2010
    I've used Seafoam for forty years. And if you want to add it to the engine oil to remove sludge and clear out the PCV system, pour half the can into the oil and the other half into the gas tank. We call this the Minnesota Tune-Up. This will not harm the engine or fuel system in any way. I apply the Minnesota Tune-Up every six months.

  • edited June 2010
    When the next step is sending your car to the scrap yard.

    I think you find in 99% cases that pouring the equivalent amount of bottled water into a full full tank does the same thing.
  • edited June 2010
    When I was a kid, I heard the old timers talk about adding mothballs to the fuel tank of the Model T to increase the octane. One could then set the manual spark advance control (the spark advance was on the steering column) and the Model T would really fly--maybe as fast as 50 mph.

    I doubt that the mothballs really did much good back then and I am certain that with today's fuels, the additives do even less good today.
  • edited June 2010
    Agree with posters; today's gasolines have quite a few additives already in them. We've driven cars to over 300,000 miles without any additives other than the odd bottle of "gasline antifreeze" in very cold weather.

    Years ago I recommended an additive called "Karbout" to my father-in-law. He only did short stop and go trips in his carbureted Buick and ran a very rich fuel mixture. Today's computerized cars with fuel injection don't have those problems anymore.

    If you are having problems with your fuel induction system, look for the real causes and fix those.
This discussion has been closed.