It's a long story that I will eventually share with all. But the bottom line is my '87 760GLE/B280F has some kind of head/headgasked/liner leak.

This is evidenced by chicken soup/chocolate milkshake/ in the oil filler cap. No coolant in the oil and really no more exhaust that has been normal for the car when cold (I've had the car for 15 years). Excellent compression and the car really does run like new.

The cooling system is tight, replaced hoses, radiator, o-rings etc. Pressure testing at 22#.

I performed a block leak test (using the blue fluid that turns yellow when combustion gasses are detected in the coolant. The first 2 times I ran this, with the car at operating temperature, it passed. After a highway drive at 70mph or so it failed...combustion gasses in the coolant!

So it keeps using a bit of coolant typically usually after a highway run and not much at that.

Soooo...not wanting to open this engine up, my venerable B280F/PRV has over 250k miles on it, I'm considering a block seal product (ie miracle cure). There are several on the market:

KW Permanent Block Seal
Bar's Leaks Block Seal Head Gasket Repair
AlumAseal (mentioned by another brickster...)

Not a permanent or long term solution but might extend it's life a bit.

Thoughts? Comments? Suggestions?

Carter