Engine coolant (antifreeze) does two jobs: it prevents the coolant from freezing in winter and it prevents the engine from overheating in summer. But coolant degrades over time and needs to be replaced periodically.
Why coolant needs replacing
Fresh coolant contains corrosion inhibitors that protect the aluminium and steel components inside the cooling system (the radiator, water pump, heater matrix and engine block passages). Over time these inhibitors are used up. Old coolant becomes acidic and starts to corrode the cooling system from the inside, causing leaks, blocked passages and accelerated wear of seals and hoses.
How often to flush and replace coolant
Intervals vary by coolant type. Older standard antifreeze (typically green or blue) typically needs replacing every 2 years or 30,000 miles. Modern long-life coolants (typically pink, red or orange, often called OAT or HOAT formulations) are designed to last 5 years or 80,000 miles before replacement. Check your handbook for the correct coolant type for your vehicle, as mixing incompatible types can cause corrosion and gel formation.
What a coolant flush involves
A coolant flush drains the entire cooling system, flushes it with clean water or flush solution to remove old coolant, scale and any debris, then refills with the correct new coolant at the correct concentration (typically 50% antifreeze, 50% distilled water, giving protection to around minus 35 degrees Celsius).
Signs your coolant may need attention
- A brown or rusty appearance in the coolant reservoir rather than the correct colour.
- Visible scale or deposits on the inside of the reservoir cap.
- The coolant level dropping regularly without any obvious external leak.
To check or replace your coolant, call Steins Garage on 0131 554 3423 or get in touch here.