Tamaroak wrote:
I recently had an oil analysis done after changing my oil before winter.
They found a significant amount of antifreeze backed up by my having to
add some during the last part of the season. It's a 1987 5.7L GMC with
closed cooling and 770 hours. It uses no oil and runs great.

I'm trying to determine the possible causes. I've heard:
1. Cracked block
2. Cracked head
3. Bad head gasket
4. Bad frost plug
5. Bad coolant pump (supposedly located on pop of the engine by the
manifold)

Any other ideas?

Capt. jeff

Do a compression test / cooling system leak down test. You have
probably a tiny headache in your gasket. Good luck. The pressure cap
on your radiator(?) has been leaking exhaust. Or, you have a crack.
X-ray, epoxy weld. Relieve end of crack with a 1/64" drill

Don't bother planing the head unless the machine shop can show you a
warp.

each guage is 20 bucks. It will save you paying a safari chasing a
golden goose. Only a girly man would do otherwise.

Go, Arnold! (I really don't know anything about his "views.")

Terry K