mine was so bad there was need for technical measurement. i mean it was like 3/16 of an inch. made popping sound that was distinctive. i would bet they would have been out of spec at 15k. BUT the jeep see's a a lot of trail time, long distance trails and local DD.
once the lowers were removed they rattled like skeleton in a trash can. they were toast and it is product of more back space 3.75 wide tires and a lot of rocks. I did not go to the dealer and plead my case for a warranty fix. I replaced them. Bought the right tool that cost more than the synergy joints.
I kept an eye on mine, measuring them every couple of oil changes. Watched them approach the wear limit, and finally had to change them at 76,000 miles. Installed Synergy...love 'em!!
That's easy, have the dealer parts guy call 4x4 supply and order it? I mean, the dealer puts on Terraflex lift and suspension components, why not something that will help safety and longevity as in they will never have to see you again.
I would be worried that if you are replacing ball joints every 6000 miles you are also wearing out the holes the BJ's press into.
The JK isn't the only Chrysler product with defective ball joints. I own a 2008 Dodge Ram 2500 Quadcab; at 60,000 miles the right and left tie rods were worn out. Since it was no longer under Chrysler warranty I paid to have new Moog ball joints and link installed. This week I received a notice from Dodge my truck was being recalled to replace the ball joints and link. This is an expanded recall from earlier this year. Like many new vehicles these TREs did not have grease zerks. The new ones do.
Back in January I received notice of a recall. I took the truck so they could inspect it; they took one minute and decided it was not the one being recalled. Then last week I received an updated recall which includes my truck. I tried to get it taken care of in January but the dealership said only certain models had the defective part. Oh well, at least now I have Moog which should last as long as I do or the truck, whichever goes first.