Short answer: You need new coolant when your car's maintenance schedule says so. Honda says a coolant flush on top of that isn't necessary except in very rare cases. Your owner's manual is the place to check.
We're not mechanics, so the facts below come straight from carmakers and the Federal Trade Commission. The sources are linked at the bottom.
What a coolant flush is
It's a service where a shop pushes the old coolant out of your engine and puts new coolant in. If your car is due for new coolant, a flush is one way to get it.
What carmakers say
Toyota, in its 2025 Corolla Cross maintenance guide: new coolant is first due at 100,000 miles or 10 years, then every 50,000 miles or 5 years.
Honda, in a 2019 position statement for its Acura cars: "Engine cooling system flushing: This procedure is not necessary, except in very rare instances (for example, to remove incorrect coolant)."
What the FTC says
The Federal Trade Commission tells drivers to "follow the manufacturer's maintenance schedule in your owner's manual for your type of driving." It also notes that some shops create their own maintenance schedules, "which call for more frequent servicing than the manufacturer's recommendations."
What to say at the counter
"Is new coolant due on my car's maintenance schedule? If not, why do you recommend a flush?"
The FTC suggests asking a shop to explain "why it recommends service beyond the recommended schedule."
For other cars
Check the maintenance schedule in your owner's manual. If new coolant isn't due yet, ask the question above.
Got an estimate with a coolant flush on it? Backseat Mechanic members text us a photo of it and find out what to fix today, what can wait, what to skip and whether the price is fair. See how it works
This is general information, not a diagnosis of your car. If your engine runs hot or keeps losing coolant, get it checked. Your owner's manual is the final word.
Sources