How many Years to you recommend between cooling system flush & new coolant ?

 

If the inside of the radiator is clean and the coolant still has good color I leave it alone.

 

About 3 years.

 

With the old green coolant the usual recommendation was at least every two years'
Starting in the early sixties a lot of cars incorporated a lot of aluminum components.
Those cars were subject to a lot of corrosion of the aluminum components if the coolant wasn't changed regularly.
This was due to dis-similar metals corrosion. (iron & aluminum)
Newer type coolants have longer change intervals. But, I don't know if they are approved for use in our "vintage iron".

 

Measure the coolant voltage. .04 VDC max, Any more its shot. PH strips work good too.
Coolant needs to be "neutral". 5 years max life span.

Pull the heater core hoses and flush it separately with low pressure.
Suck all the flush water out with a shop vac. Refill with 50/50 premix. Dont use tap water to cut straight coolant.
Low silicate coolant is nice if you can find it
A bottle of pump lubricant doesn't hurt.

Put a spread sheet together to track service dates.
Mines been in there 10 years. Time just flies too fast. Mine measures12VDC! Way over due.

Its getting flushed within the next week!!!

 

Prestone says their coolant is good for 10years or 300000 miles.

 

What's the procedure on that check, Doc? Multimeter positive on the battery and negative in the drink?

 

Other way. Positive probe in the coolant.

 

The simple answer is, back in the day, it was every 12 months or 12,000 miles. Nobody drives their collector car 12,000 miles a year, so you go by the time instead. But, as has been noted, coolant is different now with much of it being advertised as "long life." As has been mentioned, I go by how it looks, and change it maybe every three years.

If you're looking for peace of mind, change it every year and be done with it. It's not expensive, and it's simple to do, so do it if it makes you happy.


One thing I have never done is measure the voltage of my coolant.

 

Voltage drop across the coolant......I gotta see this for myself.

 

Electrolysis, it is real and damaging. Worn out/aged coolant will make it progressively worse.

 

If there's significant voltage there, yeah for sure I could see that. Interesting!

 

Great. Something else to worry about.

 

Most coolants have corrosion inhabiting chemicals added to them.
When these chemicals get used up, that's when corrosion occurs.
That's why the coolant must be changed.
"Extended life " coolants have a different additive package, It doesn't have to be changed as often as the "old green stuff ".
But it still needs to be changed.
Changing coolant is especially important in a system with aluminum components
Aluminum components are especially subject to corrosion damage.

 

My C5 Aluminum Block Vette Owners Manual says 5 years or 150,000 miles - it also mentions if it's clear no flush in necessary

 

I'm sorry, but this sounds like a damn stupid thing to do. Connecting a wire to the positive terminal of the battery and then the other end of that wire, even if it's through a voltmeter, to anything else on the engine, even a liquid, is just inviting a disaster if you should accidentally touch something metal while you're trying to "stick it in the drink." We'll put that on your epitaph. "He was trying to stick it in the drink."

You're not measuring the "voltage" of the coolant, anyway. You're measuring the resistance (or conductivity) of the fluid. There are much safer ways of doing this. Get a conductivity meter. Set your multimeter to measure resistance. Conductivity is just the reciprocal of resistance.

However, according to this article, it's all pointless, anyway, as conductivity is not a good measure of coolant effectiveness.

As I said earlier, if you're at all doubtful about the quality of your coolant, just change it. Don't be sticking electrical wires into liquids.


Check the first sentence of the second paragraph. Unless significantly diluted prior to measurement, the conductivity of automotive coolant "provides no valuable data."