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How Often Should I Flush My Coolant?

Quick answer

Most modern cars need a coolant flush every 5 years or 100,000 miles with long-life coolant, and every 2–3 years or 30,000 miles with older green coolant. In Dallas heat, follow the shorter interval if your car tows, idles in traffic often, or the coolant looks rusty or murky.

By the ASE-certified team at On-Site Mobile Mechanics of Dallas · 12 years repairing cars across Dallas–Fort Worth

How Often Should I Flush My Coolant?

Coolant types

  • IAT (green): 2 years / 30,000 miles
  • OAT (orange/red): 5 years / 150,000 miles
  • HOAT (yellow/turquoise): 5 years / 100,000 miles
  • P-HOAT (pink/blue, Asian makes): 10 years / 100,000+ miles

Signs coolant is overdue

Rusty or sludgy color, a sweet smell, temperature creeping up, or white crust around the radiator cap.

What a proper flush includes

Draining the system, refilling with the correct OEM-type coolant at the right mix, and bleeding air pockets so the engine doesn't overheat.

More questions answered

Can I mix coolant colors?

Avoid it — mixing types can form gel and clog passages.

Is a flush the same as a drain and fill?

A flush removes more old coolant; a drain-and-fill replaces about half.

Can it be done at home?

Yes, we capture and recycle the old coolant.

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