Transmission Question

I recently looked at purchasing a used 94 Lumina Minivan. After the test drive the transmission fluid was full of foam and about 8 inches to high on the stick. The owner says it hasn't been services in 70k miles. Is there anything besides overfilling that will cause foam?

Never really heard of that before. Maybe water in the transmission fluid??? My first plan of action would be to drain the transmission fluid, fill it up again, drive for a few miles, maybe drain it again to flush it out, and then fill it back up. Then check to see if it has foam. This would probably only take 2 hours or so, draining tranny fluid isn't much different than changing the engine oil.

Oh, and 70K miles is a freaking long time to go without servicing. Engine oil def needs to be changes after 3000 miles or so, and transmission fluid should be done every other time you change the engine oil. Not to mention the myriad of other things on a car that need to be serviced in a 70K mile window. My first reaction? Never buy a used car from someone who doesn't maintain it well. It will only come back to haunt you in very expensive ways.