DIY coolant test

[rocketman]

I recently picked up a DIY coolant test kit at Canadian Tire. Nothing major, just a test strip for pH and freeze pt./boiling pt. Dip it in the coolant, wait and then compare results with a given chart. My question is: if eveything checks out OK and the vehicle has no history of coolant problem, is it beneficial to drain the Rad and refill with new coolant once in a while to keep it fresh? The vehicles are a 1997 Lumina(3.1) with 58000 km and a 1999 Silverado(4.8) with 176000 km. Both have Dexcool which is still nice & pink, both vehicles run great. No flushes have been done on either vehicle. Is a simple rad drain and refill once in a while enough? If it is, is it simple as it sounds, just opening the valve on the rads, drain and refill?

 

[Big Jim]

Although GM claims that Dexcool will last 5 years or 150,000 miles whichever comes first, I change my Dexcool much more often than that. It sounds like you have pushed your luck already.

Usually Dexcool stays fairly clean. The exception seems to be when it is allowed to run too low for a while and them it allows things to get rusty.

In the absence of any indication of such rust, I would think that a drain and refill would be OK. Remember in a drain and refill, you will not get all of the old coolant out. A drain and refill usually is best if you are changing the coolant frequently.

It would be safer to do some kind of a flush. Chemicals probably not needed for a system as clean as you have described. A water only flush would probably suffice.

At least that is my opinion. Others may post their opinions as well. It is also my opinion that even Dexcool should not stay in the car beyond 3 years or 30,000 miles.

 

[goldfinger]

Treat it like normal anti-freeze, not the extended life GM hyped it to be. Drain + refill it every couple years and it will be just fine.

 

[rocketman]

I realize that a drain and refill (of the rad) won't get all of the coolant out, but if I do it a couple (or few) times, won't that eventually make the fluid "new or close to new" since it does eventually circulate? I'm a little nervous about disconnecting hoses, etc., as I'm kind of a first time DIYer when it comes to coolants.

 

[serious II]

My GM mechanic told me that Dexcool should be changed out at about 80,000 miles to avoid any problems. I also use Zerex to decrease the possibility of corrosion and keep the bearings in the water pump lubricated.

 

[Stinky Peterson]

Rocketman - what did the kit say the pH should be? Dexcool has a lower pH than conventional coolant. If it is clear and bright with no solids it should still be serviceable.

If you are going to change it I would flush with water. You will have to add a little concentrate to get a full 50:50 mix since you can't drain it completely. I don't advocate using chemical flushes unless you have a gunked up system with visible scale or corrosion.