Hood & bonnet struts

Heard some conversations a few weeks back regarding the lack of durability of hood struts on 911's. I have a freind that works for Stabilus (manufacturer). He says the following.

1) Never clean the chrome shaft with chemicals (the seal is not resistant)

2) The shocks should be facing down when collapsed, so that the oil runs TO the seal,not to the base of the strut

3) Some of the older designes were inferior when compared to today's seals. However, OEM parts are typically not improved through their life. EG Porsche spec'd a certain part that continues to be made for aftermarket with original specs. Not the newer seals, shafts, pressure, etc.

4) If someone can get a part number (preferrably a Stabilus part) off of thier struts, he could cross refference an improved design.