If I drive my truck for 30 min with just water in my system, would it be equivalent to just flushing it stationary (the proper way to flush it)? IOW, if I just drive around with a clean water refill in the coolant system instead of keeping the truck in place and then draining, would it be an okay way to flush?

1 Answer 1


It would make no difference if you are standing still or driving the vehicle. You want to ensure you have the heater wide open when you do it to ensure you are getting the old fluid from the heater core as well as the engine. Driving the vehicle around will probably allow the process to happen a little faster, as you engine will get up to operating temperature faster. The real thing you are trying to accomplish is to get the thermostat open to allow everything to circulate.

  • Thanks. I guess having the heater on while driving in 90° weather is not favorable
    – amphibient
    May 31, 2015 at 19:27
  • 2x65 air con can do the trick. Just because you have it all the way over on hot doesn't mean you have to have the blower kicking hot air out onto you. But, 90° and hot air won't mix in the cabin, that's for sure, lol! May 31, 2015 at 19:29
  • Is there any way to know the thermostat is in the open position?
    – amphibient
    May 31, 2015 at 19:31
  • A properly running thermostat will be open when the engine gets up to temperature. May 31, 2015 at 19:32
  • But is there a definitive way to tell if it's engaged or not, say when the engine is running and not going anywhere with the hood lifted?
    – amphibient
    May 31, 2015 at 19:34

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