Electrolysis, I think, David. The corrosion that occurs between iron and aluminum parts from ion exchange.

I haven't seen much of the V-6 blocks, myself. Heck, you can't see much at all on a 3.5 DOHC, and I haven't torn into one...yet.

John B.

'87 Raider 2.6 Turbo Auto, Under Construction
'95 Montero SR, 35x12.5/15 BFG M/T KM-2's, Rock sliders, Qtr panel chop, gas tank lift, 2" BL, Aisins, 5.29s
'95 Pajero Mini
'98 Montero Winter Ed.
'04 Cadillac XLR
'03 Kawasaki ZRX1200R
'60 Ford Falcon 4Dr