2/2     So one guy tells me that engine preheating is good for the car (warmed
        up oil, belts, cogs, etc move better) and the other guy tells me that
        it's only necessary for non-fuel-injected cars. My mechanic tells me
        that it's all bullshit and you can pretty much just start and go.
        Who's right?
        \_ I have a fairly new car whose instruction manual says not to
           warm up the car in idle but to drive immediately and not to
           put too much load on the car. I think one of the reasons was
           that they didn't want to be liable for CO poisoning.
        \_ Where do you live?  If it's cold, engine preheating's just wise.
        \_ my doctor said it's bs to warm up before you exercise, now
           I had to pay him to get my back fixed. [reformatd]
           \_ Who's your doctor, Dr. Quack? There's a tort there somewhere.
           \_ Some Hearsay for you: At least one study (each) has indicated:
              1.) cars that are just run gently in the first mile(s) after
                  starting fair no worse than auto's that are always
                  "warmed up").
              2.) People who stretch regularly do not have significantly
                  less injuries than people who don't.  However, people
                  who stretch ususally and then don't stretch have a higher
                  injury rate for that occasion. -crebbs
                  \_ source?  This type of inquiry seems fraught with
                     possible control issues and experimental procedure probs.
        \_ Use some common sense.  Do you think rubber, such as that used
           in belts, will age better if warmed up prior to tensioning?
           Probably, yes.  Will it make a difference in the aging of the belt?
           Probably, yes.  How much difference?  Probably not much. You might
           squeeze 5k more miles out of the lifespan of a 60k belt or hose.
           So what does that mean for you?  Cost savings, if you plan to
           keep your car that long and don't plan to follow dealer maintenance
           replacement schedules.  Will it matter in your engine long term?
           Sure.  Again, maybe a 10% gain in the longevity of powertrain parts
           (middle of the road estimate - it might be 3% it might be 20%).
           If your car is Japanese, it might mean a 220k lifespan rather than
           200k.  If American, 165k lifespan rather than 150k.  Does it matter
           _to you_? You be the judge.
           \_ what about the wasted gasoline from idling? And air-pollution?
              \_ it's unamerican to worry about air pollution.  Are you
                 a terrorist?
        \_ I've also heard from another mechanic that unless your car's in
           such a bad shape that it actually stalls if you don't warm up, it's
           better in the long run to not warm up.
        \_ Ever since my Integra hit 150k, if the engine is cold, my car jerks
           when I switch to reverse. It doesn't happen if I let the car warm
           up for more than half a minute.
        \_ it's better to let your car warm up by driving it slowly than to
           let it idle. idling puts no load on the engine, so little heat is
           produced.
        \_ search cartalk (http://cartalk.cars.com