Gas Lift Support Springs on Trap Door

Depends.

To add to the last answer, look at the support springs and look at your trap door. Do you want them to assist in opening the door or closing the door. It depends.

Like a moth to the flame, here I am again.

There is a dab of oil inside. By putting the rod downward, the oil bathes the internal rod seal. If you were to put the rod up, the oil would drain away from the seal, drying it out and failing to lubricate it.

Makes sense to me. GA

Some of what you say is true as far as the oil helping to lubricate. That's not why the oils there though. It's there to dampen the swab when it reaches full stroke. Instead of it impacting on the end it hits a cushion of oil. Will not matter which way its mounted in normal use the oil is circulated around enough to lubricate.

Have seen many mounted with the rod up.

By a far majority, I see these struts installed with the rods up. But the comment on the oiling makes a lot of sense to me.

I got this application advice from McMaster-Carr, which sells several types.

Perhaps we are confusing gas springs with "gas" shock absorbers.

Oil filled devices (shock absorbers) should be positioned fluid down. Gas filled devices (springs) should be positioned rod down.

Good point. Perhaps guest would consider giving a few more clues.