How often do you flush your coolant (if you flush it)?

[NYEngineer]

I did a full set of hoses on my 09 Suburban at around 100,000 and replaced the Dexcool. Now I'm approaching 200,000 and still on the original radiator and water pump. I'll probably do another drain and replace soon.

Not a car, but in 2003 I took a job in a commercial building with four 2000 kW Cat gensets. During commissioning, I was told the engines were filled with red "lifetime" antifreeze. I was skeptical but said ok, you guys are the doctors. Five or six years in, I decided to have the coolant tested . I took samples from each engine and when I got the results back, I was none too happy. I learned that the coolant was NOT lifetime but more of a test it every year and treat with an additive as per test results. I flushed all four engines, bought new red coolant and mixed it with water from my deionizer. I had it tested every year and treated it as per required. Ended up much happier in the long run.

 

[Kira]

A 4 banger I maintain has seen two "radiator dumps" over 11 years and 116K miles.
Turns out exactly 1 gallon of coolant drains when you pull the plug. EZ to keep clean.
What's a good brand and/or source of coolant test strips? There MUST be cheap ones to avoid.
Thanks

 

[SEMI_287]

Usually every 3 years. Speaking of which I need to do that in the BMW. Mmmmm I'd love an E90.

 

[ARB1977]

Just did my 15 Tacoma 4.0L. It’s speced 5 years or 100K. Just over 5 years and close to 100K. I think it’s 5 years 50K after that.

 

[joekingcorvette]

I usually do all my vehicles every 2 or 3 years and use the Lisle no spill funnel to make the job easier. I just do a drain and refill with no flushing at all.

 

[2strokeNorthstar]

I change my coolant once a year on my car.

Yes I know its overkill, but 2 Gallons of Dex Cool costs $15 and it only takes 15 Minutes to do.

Apparently the best way to prevent HG failure on a Northstar is to change the coolant often. So that's what I do.

Tick tick tick...boom. Just joking. Our Northstar never had a head gasket issue in 180k miles when sold. Coolant crossover and water pump leaked and repaired but that’s it. Burned a lot of oil and front motor mounts were a quarterly item

 

[MCompact]

I have a 2009 BMW 328. BMW claims it's "lifetime fluid". There's no such thing as "lifetime fluid". The last time the coolant was flushed was in July of 2018 at 64k miles(by the PO). I am at 72k miles right now. I plan on doing a coolant flush later in the spring or summer. I'll probably stick with flushing it every 3 years (Since I hardly drive the car).

I watched a video on youtube where the guy drained the coolant from the drain plug and then ran the water pump while the coolant was still draining. Isn't the water pump running dry?? From what I am reading, a lot of folks drain it from the drain plug and then drain it from the water pump/thermostat hose.

Here's the video:

Every two years for my BMWs and Mini- using BMW OEM coolant.

 

[ARB1977]

Did my 15 Tacoma this past spring for the first time at 98K. I believe it’s 5 years/50K after that.

 

[DBMaster]

I'm experimenting, assuming the risk so that I can learn and share. I have a 2012 Mazda3 (Skyactiv) that came from the factory with FL22 coolant. I'm at nine years and 120,000 miles on a coolant that has a first replacement interval of 122,000 miles (weird, yes, but from Mazda, not me). I started adding RMI-25 to the coolant at 15,000 miles and have done so every 15,000 miles since, after reading about it on BITOG and doing a SMALL amount of research. My intention is to never change the coolant unless required due to hose or component failure. Based upon the ratio listed in RMI-25's literature I've been adding 4 oz to my approximately 2 gallon coolant capacity at those intervals. The 2012 Mazda3 retains the pressurized coolant recovery tank (likely due to Ford's influence) versus the later models' unpressurized one. Knowing that it doesn't mean much, I've never seen any debris in the overflow tank and the coolant still looks and smells like relatively fresh coolant. Again, these observations are highly subjective. The general point is that engines and fluids have experienced substantial evolution since my days as a "young mechanic" (to quote Scotty Kilmer) and I felt the need to push the limits of widely accepted maintenance intervals.

FYI, if I do ever have to change the coolant I intend to use Peak Final Charge as my go-to.

I am neither suggesting nor recommending that you follow my example. I simply feel like we need to be willing to accept that some of our long held notions may be obsolete.