How do I clean my radiator?

Q. Is there a product or a process to clean aluminium radiators and oil coolers? You could eat your dinner off the rest of my bike but these get covered in crap and corrosion. It can’t be good for their efficiency and looks naff.

Pressure washing is going to flatten the fins and over-aggressive chemicals could be a bad idea on alloy. Take them off and dunk them in something, but what?
Pete Judd, email

A. The cores of rads and oil coolers are pretty fragile and any sort of chemical like caustic soda or hydrochloric acid will eat into the alloy.

Even detergent and brush could be enough to flatten the fins. Sponging caked on dirt very gently, then using a garden hose set to ‘mist’ or ‘spray’ to gently rinse out the crud could work, though sometimes the caked in dirt is what’s holding the radiator core together and it may spring a leak after a god clean.

The only other method I’ve heard of to get totally dry dirt off is with a high-pressure air line, but don’t get too close…..