You unscrew it :S
It is the automatic air leveling system. If it runs constantly you have a blown rear shock.
Drain or petcock should be a the lower of rear of radiator or remove lower radiator hose
From the inside of the trunk
under rear seat
The 1995 Buick Skylark is equipped with rear shock absorbers. There will be struts on the front of the vehicle.
What year? Most are rear disc from some where around 79 and on?
It's located under the rear passenger seat.
the battery is located under the rear seat.
YES A Rendezvous does has a shock and a strut on the rear.
from underneath the car you can get right to them
Check your rear pads and brake calipers
If it's like all the Riviera models from '95 thru '99, it's under the rear seat, passenger side.