Not sure if kroil will have the same effect, it might. I think this could be a case where WD is being used for it's actual application (it's not a good penetrating oil, Kroil is way better for that) but WD-40 is better at displacing water. So if you spray it on the oring it makes it naturally want to pop away from the water in the cooling system. __________________ ~Dave~ 98 328ti Morea Grun slicktop 11 128i space gray slicktop 13 JGC WK2 Deep Cherry Search | RealOEM |