why not call tein and ask how long they reccomend use before replacement?
that'll give you an estimated idea of how long they should last.
You're right. I have called Tein numerous times. The Tein reps told me to overhaul the coilovers every 30,000 miles or so if I'm lucky. They also said less if I'm not so lucky to get some dirt or debris rubbing into the shaft of the damper piston.
For what the coilovers were meant for, I would honestly say 30,000 miles plus 10 or 20 thousand if you are nice to them. Then it's a definite overhaul from my experience.
I'm going to have my SSP's overhauled now and possibly my HA's later. I was thinking going custom Tein. Tein will do a custom spring and revalve according. Tein also has strut bars out for those that didn't know.
Coilovers are not meant for lowering purposes and Tein isn't the best by far, but these coilovers need to be driven hard or don't bother even looking into them.
There's a whole list of things you can get done to used or abused Tein coilovers from the Tein site. That list explains all and if you are going to get them checked out by Tein, you need to print out and fill out the list.Tein Price Overhaul