The Ultimate Guide to Black Coolant Unraveling its Cooling Potential

Try draining your radiator to see if there is oil mixed with the antifreeze. That could mean a blown headgasket or other serious engine problems. My coolant (which was red not too long ago), has suddenly turned black. The level hasn't changed, it's still just up to the fill line, but it's got me worried. I have used Peak Coolant Flush 40+ times with subsequent distilled water drain and fills until clear liquid came out. A precipitate can form as a reaction between some antifreeze corrosion packages and that of the WaterWetter. It isn't harmful, it can form in ... so for the past 2 years black spots keep appearing on the coolant tank walls, the coolant itself is crystal clear there is no oily residue ... Another possibility on the black coolant could be that there is residue still in there from some improper coolant or additive that someone put ... In general, black coolant may be caused by a few issues. There are different ways to diagnose each of the mentioned causes. Black could be aluminum corrosion since most of the system is made of that. Might be it never got properly rinsed out, I'd be doing it again.... Black bottle Usually an indication of leaking head o-ring. Does it build pressure in the bottle too? If the o-rings leak you can push oil into the cooling ... ^Yep. Do a few drain/fill cycles, probably start with distilled water (90 cents a gallon at the grocery store) until you get it clear then fill ...