Q. My comments and questions are about antifreeze. Some say it lasts two to three years when you buy a car new. Some say you can extend that to five years or 150,000 miles. Then others recommend a heavy-duty extender to 400,000 miles. I need help here.
I have been taking care of my cars since I was 16, back in 1962. I have learned throughout the years, while living through antifreeze shortages, that you can extend the life safely.
I have extended it in my 1998 I30T Infiniti with the standard ethylene glycol antifreeze. I know they have made antifreeze improvements over the years, making it last to 150,000 miles. What I do is add rust inhibitor every-other year. The car currently has 220,000 miles, and the antifreeze was changed at 200,000 miles when the car was 14 years old.
I am now doing the same thing in my new 2007 M35x Infiniti. It has 80,000 miles and I have just begun adding rust inhibitor every two years. I do the same thing to my wife's 2008 RX350 Lexus. I started doing this in my cars about the 1970s or so, whenever there was that antifreeze shortage.
You thoughts on my process for the antifreeze?
A. Great question and you probably will get a whole bunch of different answers from professionals in the business, and none of them would be wrong. Here are my thoughts on the matter.
Most of today's cars come with long-life coolant in them. This coolant has better additives and it definitely protects longer than the old green ethylene glycol will. The concern I have, as we move to less frequent oil changes, extended coolants and spark plugs, is that infrequent changes can be misconstrued by the car owner as no maintenance being required, or the maintenance services are forgotten about all together.
Over time, coolant will turn acidic and the additives start to wear out, which can cause gaskets and other components to deteriorate.
If you have an older car that is using regular coolant, I would recommend flushing it out and changing it every-other year, or about 30,000 miles. With a long-life coolant you can at least double it and maybe a little longer, depending on how the coolant looks.
Can the coolant go to 100,000 miles? Maybe, but why push it to the limit? The savings does not outweigh the possible wear and expense this can cause.
You can also test the coolant to make sure it is not acidic and that it still protects against freezing. This can be done using a special dip strip that you can buy from the auto parts store, and you use it just like you would test your pool water.
Lastly, anytime you need to change a component, like a hose or a water pump, you will be losing a good amount of coolant anyway. So this repair is a great opportunity to change out all the coolant. It is very probable such a repair will time out with the change interval anyway.
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