[OT]: Does the Cooling Fluid Need to Be Changed?

Jul 18, 2026 Last reply: 1 week ago 5 Replies

An elderly friend has a 2013 Mazda CX9, 162,000 miles, runs great. He takes care of it.



A whole set of new tires was purchased a month ago from the local Wheel Works franchise, along with a road hazard policy.



He took his car to Wheel Works to have a roofing nail removed from his left rear tire. They said the nail, although in the tread, was too close to the sidewall to patch. Since he had a road hazard policy, they pro-rated the tire and sold him a new one at the pro-rated price. This all seemed reasonable.



But, they also wanted to sell him an oil change, which he didn't need at the time. (I change his oil when needed.)



Here's why I'm writing...



They also told him that they checked the acidity of his cooling fluid, and said it was so acetic that it should be changed or it would eat away at the seals/gaskets in the cooling system. The cost would be $168. He refused and asked me what I thought.



I don't have an opinion, but I've never changed cooling fluid even in much older cars. Should he change the cooling fluid? Should I believe this?



(An aside...his check engine light went on two days ago. I ran a diagnostic, which showed he needs to replace the O2 sensor. Funny that Wheel Works never said a word about this.)



Thanks.


Has it ever been changed?

My car says: At first, replace at 120,000 miles (200,000 km) or 120 months. After that, replace every 24,000 miles (39,000 km) or 24 months

Given age and miles, check the hoses too.

I'd not expect them to catch the O2 sensor though.

Yes, the coolant should have been changed already - it is 13 years old so WELL past time. There would be no way for the tire shop to know the O2 sensor was about to fail

I found out the hard way after 2 heater cores (my '86 GMC pickup) failed due to galvanic corrosion . That charge to drain , flush , and refill sounds kinda high but I don't know the hourly shop rates or materials cost in the OP's area .

My 2007 Toyota service manual specified a coolant change at 50 or 60k iirc. It might have been the usual hype but it called for the super special formulated Toyota coolant, which wasn't cheap.

I think the 2013 showed a coolant change at 100k. I'll have to look but I don't think the 2018 manual even mentions it.

The charge does seem high but like everything else the newer specs ain't your grandfather's Prestine.

Simple to just Google up for year and model. I just did mine:

First Replacement: After 11 years or 137,500 mi (220,000 km) Then: Every 6 years or 75,000 mi (120,000 km) thereafter

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