When my 98 3.9 automatic Dakota had around 100,000 miles on it, there developed a mildly irritating surge, when on cruise, as the torque converter un-locked and re-locked. I had three dealers and two (including THE Mr. Big) transmission shops tell me a new transmission was in order. But...as I had been sending samples in for analysis, I rang up the guy in the white lab-coat at Amsoil's Oil Analyzers, and we had a talk. He told me the reports not only didn't show abnormal wear, the report showed unusually low wear. He said there was nothing mechanically wrong with the transmission. The transmission did fail me. At 450,000 miles the solenoids bit the dust. I still put Amsoil ATF in it......and it is still running at 528,000 miles. The surge? Throttle position sender. Moral of the story; Oil Analysis Works.