" From: farna@xxxxxxx " " " it's at an acceptable rate. I don't think there's anything you can do " about it either. Maybe one of those electronic cathodic protection " systems? In principle they should protect EVERYTHING grounded to the " car, as long as you have a sacrificail anode (or is it cathode?) " attached. We use those for underground pipe protection, so in theory it " should work on a car. sacrificial anodes, usually zinc. marine guys know all about sacrificial anode systems! talk to a powerboat yard that does repair or construction. another thought - wrap the nipple threads in teflon tape to try and insulate the iron from the aluminum manifold. ps. that web site talks about rust protection - which doesn't work - and doesn't mention cooling systems. ________________________________________________________________________ Andrew Hay the genius nature internet rambler is to see what all have seen adh@xxxxxxxxxxxxxxxxx and think what none thought