I took my 1983 MB 380SE (195K miles original - engine hasn't been rebuilt) on a trip from LA to SF (about 350 miles each way) and noticed blue smoke coming out my tailpipe when I hit the uphill roads of the "grapevine" (the hills around Bakersfield).

I noticed that the smoke got thicker as I removed my foot off the gas. The smoke lasted about 30 seconds but disappeared as quickly as it appeared.

The car doesn't smoke at all at idle or startup. It also doesn't drip any oil on the ground. The only time it smoked again was on the return trip when I hit some uphill roads.

Is this the valve seals?
Does the incline of the road affect where oil gets into? I don't see smoke when I mash the throttle on flat roads...

How hard is this to fix, if it's a problem at all...
Do the heads need to come off to do this work?

The car runs fine and clean otherwise.

If you have any other ideas, I'd appreciate your input.
Thanks in advance.