Reasons coolant is low when there are no visible leaks. Coolant is added, but the radiator keeps losing coolant and going empty.
Amazon Link Coolant Leak Detection Dye: https://amzn.to/47mHsk8
Amazon Link Radiator Pressure Tester: https://amzn.to/3MQ2uzl

Possible Causes
Bad Radiator Cap
Blown Head Gasket (Exhaust Smoke is White or Coolant in Oil)
Hard to See Leak That Dries Up
Wrong Coolant Mixture (Usually 50/50 Mix)
Leaky Heater Core

How To Find a Hard to Spot Coolant Leak
Replace Radiator Cap with Correct OEM Unit
Pressure Test the Radiator
Use A Bottle of Coolant Dye

By using this information user assumes all risk of use.
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