Radiator Flush: cooling system cleaning before antifreeze change

The car's cooling system is often ignored until the first overheating. But limescale, internal rust of the block, residues of old coolant and oil traces (from gaskets that seep) deposit over the years reducing heat exchange efficiency up to 30%. The professional solution: a cleaning with Pro-Tec Radiator Flush before every antifreeze change.

When the cooling system needs cleaning

• Cars over 5 years or 100,000 km never treated
• Engine temperature tends to rise more than normal in city or uphill
• Expansion tank with brownish, black or oily residues
• Dark or cloudy coolant
• Inefficient cabin heating
• Before a scheduled antifreeze change
• After a repair (thermostat replacement, water pump, hose)

What Pro-Tec Radiator Flush contains and how it works

Pro-Tec Radiator Flush contains surfactants and chelating agents that progressively dissolve:

• Limescale deposits in engine block conduits
• Internal ferrous rust
• Oily residues from seeping gaskets
• Sediments of old coolant
• Slime and organic sludge

Does not damage plastics, rubber hoses, radiator aluminum alloys or thermostat seals. Safe on all cooling systems, from petrol to diesel cars.

Complete procedure (1 hour of work)

1. Engine cold
2. Open the expansion tank (carefully!) and check coolant level
3. Pour the entire Pro-Tec Radiator Flush 375ml bottle into the expansion tank
4. Top up with distilled water to MAX
5. Close and start the engine
6. Run for 20-30 minutes at 1,500-2,000 rpm until operating temperature
7. Keep cabin heating at maximum (to circulate the flush also in the cabin heater)
8. Turn off the engine and wait for complete cooling
9. Drain ALL old coolant (via radiator cap or low hose)
10. Rinse with clean distilled water (repeat 1-2 times)
11. Fill with new antifreeze of correct specification (e.g. PowerTec G12)
12. Bleed the circuit according to your car procedure

Which antifreeze to choose after the flush

After cleaning, only use coolant of the correct specification for your car:

• G11 (blue) – pre-2000 cars, IAT specification
• G12/G12+/G12++ (red) – modern standard, OAT specification
• G12evo – recent Volkswagen Group (after 2018)
• G13 (purple) – VW Group after 2012, also known as G12++ HOAT

What to do if you find oil traces

If the drained coolant has oil traces, there's a leak from gasket or oil cooler. Before the new refill:

• Add Blue Chem Oil Cleaner Cooling to remove oily residues
• If the leak persists, evaluate PowerTec Ripara Testate for microleaks

Common mistakes to avoid

• ❌ Use tap water (limescale recreates the problem)
• ❌ Mix antifreezes of different specifications
• ❌ Skip rinse after the flush
• ❌ Open expansion tank with hot engine (burn risk)
• ❌ Leave the flush over 30 minutes (scheduled time is enough)

Recommended products on LS Motors

• Pro-Tec Radiator Flush 375ml – professional cooling system cleaner
• Blue Chem Radiator Stop Leak – stops minor leaks during treatment
• PowerTec Antifreeze G12+/G13 – quality coolant for new refill
• Blue Chem Oil Cleaner – removal of oily residues from system

Pro-Tec, Blue Chem and PowerTec original German additives. Shipping 24/48h in Italy.