It is perfectly OK if you want to grease the slide pins. It is your vehicle.

But I think it is worth noting that they are not designed to be greased. They work just fine not being greased. If any mechanic or DIYer out there feels that they know more than the team that designed the slide pins, I wonder what that belief is based on, other than habit? BMW has gone to some trouble to include the do not grease message in the TIS and training materials.

You brought up the 17 years. Sorry if my comment sounded harsh, it wasn't intended that way.

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2007 X3 3.0si, 6 MT, Premium, White

Retired:
2008 535i, 6 MT, M Sport, Premium, Space Grey
2003 X5 3.0 Steptronic, Premium, Titanium Silver
2002 325xi 5 MT, Steel Grey
2004 Z4 3.0 Premium, Sport, SMG, Maldives Blue