First, let me say this was NOT my idea. I read a post another Z owner made who tried this same thing. I just changed it a little. Also, I just finished trying this, so I cannot say if this is a permanent solution. Oh, and still one more thing, the some owners mentioned on the original posts regarding this window grease "fix" that it DID NOT work for them, or that the grease came back after a week or so.

Anyways, as mentioned by a previous member whose name I unfortunately can't remember, he put fabric medical tape on his window where the grease streak would commonly appear and put his window up and down repeatedly. According to this owner he was successful at eliminating the grease. I tried this but was unsuccessful. Then I took the tape and applied it in small strips at a 45º angle to the streak (see picture) and put the window up and down maybe 3-4 times. I took that tape off and re-applied more tape and repeated up and down with the window. Surprisingly the grease disappeared on the driver's side window. So I went to the passenger window where the grease was even worse. I repeated the steps above. The grease was cut in half if not more. Unfortunately it was getting dark and I wasn't able to apply a third set of strips. But I'm optimistic that a third grouping of tape will eliminate the problem. Now, for how long it eliminates it is another issue, but I'll keep everyone posted.

I wonder if spraying the tape with windex or some other solvent will help?

 

sounds like a good idea. I have yet to c the grease problem, could u post pics, if ne1 has them, of what the grease streaks actually look like.

If it is just a matter of eliminating the excess grease from inside the door, then the tape should eventually soak it up. If its a design problem, then id take it back to the dealer.

 

Fortunately or unfortunately, I don't have as bad a grease problem as before since I tried this tape "fix." So I won't be able to (at least at this point) post pictures of the problem. Since this is such a widespread problem, I'm sure someone out there could post a picture or two.

This is definitely a design flaw, and I'd love to take it to the dealer to get it fixed. But after reading posts by owners who went the dealership/TSB route, I got a little worried that the "fix" caused even more problems. So I'm hoping taping the window will remedy one of many frustrating problems. I'll keep everyone posted.