antifreeze

[herbwhite59]

How often should I change antifreeze in a late model vehicle? I`ve been changing it every 2 yrs. but my mechanic says that`s wasting money. Do I need a new mechanic?

[trader_4]

I'd say ~7 years, 100K miles. The antifreeze itself will protect against freezing probably for the life of the engine. But it has corrosion inhibitors that don't last forever. And make sure you use the correct antifreeze for the vehicle. Some of them now have antifreeze that's supposed to last even longer, for the life of the car, etc. But I'd do it at around 100K or if you have to do some work around that where draining it happens anyway, eg water pump replacement.

[Colonel Edmund J. Burke]

You are one stoopid shit.

[Ralph Mowery]

BS

[Frank]

Thread prompted me to check my service manual and it says 137,000 miles or about 13 years. Just put your car model and date and google it up. I suspect your mechanic is correct but don't worry, your mechanic will not fire you.

[Wade Garrett]

Read the maintenance section of the owner's manual provided by the car's manufacturer. Do what it says there

[Clare Snyder]

Actuallt the test CAN be valid - but you need a baseline.

If you test the voltage on a new car with fresh antifreeze with a high impedence meter (preferably digital) and it reads 0.2 volts, and a few years later test it and it reads 0.6, you DO know the pH of the antiftreezehas changed.

Easier touse a pH tester, test strips, or titration to check. There ARE pH buffer additives that can be added to coolantto restore the pH, and when installing new coolant the pH should be tested and ideally adjusted, because the pH of the water used can actually make the mixture too high or too low in pH right from the start. High pH can lead to radiator "scaling" which will eventually plug the rad, while low pH will cause corrosion of the radiator

For example,your water has a pH of 7.0 and antifreeze has a pH of

10.5, so a 50-50 mix has a pH of 8.75, and that's too acidic to protect the cooling system, so the pH must be modified to something around 10 to protect the dissimilar metals in the modern cooling system. The target range is 9.5 to 10.

[Ed Pawlowski]

Your mechanic is a keeper and wants to save you money.

Most are about 5 years and 60k too 125k miles. Check your manual and use the right type.

[rbowman]

Have you ever thought about reading the owner's manual? Mine has the recommended service intervals.

[Ralph Mowery]

Somewhere I seem to be missing something in this.

You seem to say that if you mix the antifreeze 50/50 like much of it is recommened by the company , you still need to add something to it to bring the PH back to your numbers ?

Most water should have a PH of 7.

Why would you add something to the mix as recommended by the factory, and what would that be ?

[Clare Snyder]

You would add a pH buffer - a commonly used one is basically borax. You add it to get the pH set to where it should be for maximum cooling system life and efficiency. Don't ask me why coolant manufacturers don't buffer it properly for common water, but they don't.

This has been true for AT LEAST 40 years - It has really just come "to light" in the last 20 years or so since antifreeze recycling and reconditioning became feasible. Solid state pH testers have made testing a lot easier and more accurate as well.

We used to use test strips to check the pH and commercially available buffers. I used to check the coolant ph at the dealership to prevent corrosionin the cooling systems of my customers' cars.

Then I got my hands on the electronic pH testers after I was out of the trade, and my brother was in the business and got a antifreeze recycler. Made his life a lot easier and made him a lot of money - saving his customers a lot more. I've got a few bottles of lab grade pH buffer from my chemistry prof neighbour left over from the testing I did on the pH testers about 15 or 20 years ago. - don't have a functioning tester any more so it's back to the test strips for me.

[Clare Snyder]

The thing is, if the manufacturers BUFFERED the antifreeze properly it would correct itself tothe proper ph.

A buffer is "selective" in that it will either raise or lower the pH as rerquired to maintain a specific pH.

pH correction and pH buffering are two different things.

If the pH is too high I can correct the ph by adding an acid like Hcl (Hydrochloric acid). If the pH is too low I can correct it by adding a base, such as bicarbonate of soda (sodium bicarbonate).

This "balances" the pH at a point in time.

Addition of a pH BUFFER will workto maintain a given pH - "buffering" it against both acids and bases.

Each "buffer" solution has a "target pH" which it fights to maintain.

If i CORRECT the pH of the antifreeze solution to 10.0 and add a quantity of 10.0 buffer solution, the pH will stay at precisely 10.0 untill all the buffer is used up . The buffer contains "complimentary" compounds - if it reduces the pH the compound produced increases the ability to increase the pH in the future and vice versa - from what I recall.

[trader_4]

I'm with you on this one. The idea that for a century coolant manufacturers are selling product that you have to add crap to in order to make it right doesn't pass the common sense test. And that auto makers also don't warn consumers that they can't just put 50-50 coolant of the proper type in the vehicle. If this was the case, Prestone for example, would be formulating and marketing their product as having the right PH, no need to damage your car or add more chemicals to it like you do with all the others. They would have a superior product. Also there are now several kinds of different antifreeze with different formulations, different additives, for various kinds of cars. If this PH adjusting and testing had any validity, it was probably for the basic antifreezes in use 50 years ago.