First the history: last week our '81 a/c tanagon got new hydraulic
lifters fitted at a local shop, then went to a different place for a
transmission checkup.  At the tranny shop, with the van on the lift,
there was a largish pool of oil on the floor, looking like it came from
the pushrod tubes above the heat exchanger.  Back to the local shop,
arriving in a BIG cloud of oil smoke (outside and inside from the
heater), who said the rocker cover had been leaking and they fixed it
(free.)

Now the problem: picked up the tanagon and drove home late, last bit is
a very steep 100 ft driveway.  At the top, another cloud of smoke and a
cupful of oil on the ground.  Could this oil have been sitting somewhere
inside the engine, draining out (over the heat exchanger) only when I
drove up our steep driveway?  Otherwise the leak must have sprung again.

The van is back at the local shop, who are checking again, but say
there's so much oil it needs steam cleaning before they can tell much.
That's not possible before the long weekend so any insights would be
helpful.  My other car has just split its radiator so maybe the weekend
will all be walking.

I should be under the van myself, but work's getting in the way (and I
don't have risers or a lift.)
Thanks
Alan