Koni vs. Bilstein question

[Zsolt Kovacs]

Further to my quest to update my suspension, I was just talking to a respectable
german car specialist who said that in our climate Koni is not a good idea,
because the top seal freezes in extreme cold and it will leak. I am located in
Alberta, and it does get down to -25 F for a while in most winters. The car I am
planning to modify is an 88 5k tq.

I am wondering about two things.
1. Is the mechanic right? Has anybody experienced such problems? (I am hoping I am
not the only one on this list who lives in a cold climate)
2. I am now considering going with Bilstein Sports. Any advice? Good? Bad? BTDT?

The springs I am planning on using are H&R.

Thanks,
  Zsolt