clr cleaner but make sure u flush it out good or just visit a radiator shop and have them flush it out
Larry is right, my car was running warm ,tried rad flush, helped A little .I bought A nice champion 2 row 1in tubes radiator on eBay for $178 free shipping . It made A big difference, car is running A lot cooler,setting in traffic ,running it hard down the road,temperature gauge stays the same .
A good radiator shop will remove the tanks and "core" or"rod" it - basically cleaning the tubes by running a rod through them. Best way to clean.
Get new, my Modine has been in car since '82. With a 180* stat, it runs at 180*, maybe climbs to 185* if it's 90 degrees outside.