W124/M103 head gasket leakage

[taaboo]

At 160K our '89 300TE has been a wonderful car. Owning older German cars as a rule, I was not too concerned with the high maintenance we've had on the car this year as it's 11 years old and things don't last forever. We've spent about $3000 on it so far - major A/C renovation (how about that $700 hose setup!), new exhaust system, a myriad of transmission and power steering hoses, etc.

So now to the point - mechanic says "You've got oil seepage from the back of the head, we'll need to keep an eye on it". I see there has been a lot of activity in the archives about this, but a thing or two remains unanswered. If I may:

(1) is there a reason for this on an otherwise superlatively over-engineered automobile?

(2) oil usage is definitely noticeable with this "seepage", but it only seems to be an issue on trips, e.g. extended periods at highway speeds 8^). Don't seem to notice around town. Car runs/idles perfectly.

(3) will this tend to "seep" a long time, or should I be concerned about catastrophic failure many miles from home ...

(4) the money question: the motor runs soooooo good, with good gas mileage and the plugs a consistently perfect whitish-gray ... I'm contemplating simply yanking the head - leaving everything on it I can according to the shop manuals - and replacing the head gasket. Lift head, remove old gasket, install new head gasket, reinstall head, be done with it. IOW, don't mess with the head even though it's off the car ... am I being shortsighted?

Comments? Thanks for the bandwidth and support.

Brian