📋 Quick Answer
Drain & Fill
$70–$120
Full Machine Flush
$100–$200
Interval
60k–100k mi
DIY Difficulty
Moderate
A coolant flush and a radiator flush are usually the same service: a shop drains the old antifreeze, runs flush solution and water through the system, then refills with fresh coolant. Some shops use "radiator flush" loosely to mean just a drain-and-fill of the radiator (which leaves up to 50% of old coolant in the engine block). A true full flush uses a machine to push every drop of old fluid out and runs $100 to $200. A drain-and-fill is $70 to $120.
🔍 Detailed Breakdown
#1
Drain and Fill (sometimes called radiator flush)
Tech opens the radiator petcock or removes the lower hose, drains what comes out, and refills with new coolant. Removes maybe 50% to 60% of old fluid. Cheap and quick but does not fully clean the system.
100%
Cost
$70–$120
DIY
Easy to Moderate
Severity
Use when coolant is still mostly clean
#2
Full System Flush (true coolant flush)
Tech connects a machine to the radiator or upper hose that pushes new fluid through while old fluid drains, often with flush solvent. Removes 95% or more of old coolant. The right service if the coolant is brown, rusty, or you bought the car used.
100%
Cost
$100–$200
DIY
Hard at home
Severity
Use every 60k–100k mi
#3
Chemical-Only Flush (flush additive)
A solvent is poured in, you drive 15 to 30 minutes, then drain and refill. Cleans light scale but skipped by most modern shops because aggressive solvents can damage gaskets and hoses.
100%
Cost
$10–$25 (DIY)
DIY
Easy
Severity
Use cautiously
#4
Power Flush (high-pressure machine)
Pressurized machine flushes the entire system including the heater core. Most thorough and recommended if you have heater problems or brown coolant. Costs more because of the machine time.
100%
Cost
$130–$250
DIY
Shop only
Severity
Best for neglected systems
🔗 Related Guides
❓ Frequently Asked Questions
Are coolant flush and radiator flush the same thing?
Most shops use the terms interchangeably. Technically a radiator flush could mean just the radiator portion, but in practice it almost always means a full cooling system service.
Do I need a flush or just a drain-and-fill?
If your coolant is still translucent and the recommended color, a drain-and-fill every 30,000 miles is fine. If it is brown, rusty, or you do not know the maintenance history, get a full flush.
Can a coolant flush damage my car?
A proper flush with the correct coolant type is safe. Aggressive chemical flushes on older cars can dislodge crud that clogs the heater core, and using the wrong coolant type can damage gaskets within months.
How often should I flush my cooling system?
Every 60,000 to 100,000 miles for most modern vehicles, or every 5 years, whichever comes first. Check your owner manual for the exact interval and required coolant type.
Will a coolant flush fix overheating?
It can if the system is clogged with rust or scale. It will not fix a bad water pump, stuck thermostat, blown head gasket, or a leaking radiator.
Should the shop also replace the thermostat?
On vehicles over 100,000 miles or if the system was very rusty, yes. The thermostat is cheap (about $20) but if it sticks shut after a flush, you have to redo the work.