I used to perform ‘topside’ oil-changes for many years. However, one must be certain that they can suck all the oil out of the sump.
When I purchased my Subie with the timing chain, I studied the engine diagrams and determined that the dipstick tube does not go into the bottom of the oil-pan. (it goes into the bottom of the timing-chain cover)
If anyone has successfully sucked all the oil out of the engine THEN opened the drain-plug to validate they got all the oil out PLEASE TELL US.
For now, I installed a Fumoto oil-drain valve. It is easy enough to slide a drain-pan under the vehicle, reach under and open the valve. With the vehicle sitting ON THE GROUND, the drain-valve is accessible by lying under the FRONT bumper and reaching underneath the engine.
