Opinions on service life of coolant
 

Greetings!!
Back in 2013-14 when I restored my 67 GTO I went through everything including engine rebuild, trans, etc. Upon reassembly, I installed a 3-row aluminum radiator so I decided to use the GM Dexcool extended life coolant. I also used a bottle of Water Wetter. I did have a very slight heat issue the first summer but it has long been taken care of. Smooth sailing ever since. So to the question: Without any issues at present, should I be concerned about flushing/replacing coolant? Input appreciated!!!

Chemnick:old:

The general rule of thumb is every 2 years, but to be more specific it depends on the rate of pH degradation in your particular engine/radiator. If you want to keep track of things and change the coolant only when it actually needs to be changed rather than a predetermined schedule, buy some inexpensive coolant test strips: https://www.amazon.com/Cool-Trak-311.../dp/B000MIUJMO.

However, I'm not necessarily opposed to just changing it every 2 years regardless of pH. I think there is a benefit to making a routine habit of getting underneath your car and looking around for other potential leaks/issues while you're taking care of something else such as changing the coolant. Sometimes we need an excuse to get underneath and have a look-see.

Mine has been tested every fall for 18 years and looks good and tests good every year. I use a multimeter to check it.

Coolant check
 

Please explain method for checking coolant with a DVM.
Thanks. Gerry.

What is the preferred coolant these days for a vintage Pontiac? Is there something that helps protect the aluminum timing covered compared to the old products that didn't do that great of a job?

Like me, I'm sure most here use "regular" off the shelf coolant that is safe for engines that have aluminum components. You can also add an anode like so: https://www.rotometals.com/flex-a-li...4-npt-x-1-3-4/.

I found this online:
https://www.readersdigest.ca/cars/ma...nt-multimeter/

Ahh...better change it in my 99 GMC with 119k miles.
Had 15 years and haven't touched it except for brakes, o/c's, and tires. No idea if was before that.
Course now something probly happen...

Dexcool is supposed to be good for 5 years or 75,000 miles. Been running Dexcool in both of my newer GM vehicles and change it every 75k. No problems noted with either (Cadillac has 208K, Silverado 178K)

GM has been using Dex Cool since 1996. Their recommendation is 5 years or 150,000 miles, whichever comes first. It works really well. They also recommend distilled water. I am not sure about the voltmeter test. It has been a long time since I tried it. Dex Cool was formulated to better protect aluminum components better than the previous coolant. A lot of problems with it have been from the gaskets with the particular engines that it was put in. I have used it and will continue to use it in my Pontiac's.

PH test strips are a good item to use.

multimeter
 

Sorry I took so long to get back to you. To check condition of your antifreeze with a Multi or volt meter: Connect the Positive lead of the voltmeter to the engine block, set scale to 20 volts, Insert Negative lead in radiator coolant and read meter. If voltage reading is between 0.01 and 0.05 coolant's PH is okay.

Unless they have changed the formula, back it 2003 the Dexcool was good for 10 years or 100,000 miles. That's what we were taught in GM training school.