That would probably be the case in a relatively new transmission, or if the fluid is thickened too much. Slightly heavier fluid will increase internal pressure, will improve shifting, and can help an aging trans along for a few more years. One pint can of STP shouldn't affect 10-15 quarts of trans fluid that much. I used to run engine oil stabilizer (a quart -- the stuff you see on counters with the crank gears) in my M-35, even shortly after a rebuild. It made a noticeable difference in shift speed (faster, harder, less slipping). It was the closest thing to "shift kit in a bottle" that you could find! That said, no more than 10% should be used. The M-35 holds 12 quarts of fluid, so one quart was less than 10%. I've run 1/2 quart in my Volvo 960 and my AW4, but really didn't notice any improvement in those, probably because they are newer, tighter (by machine work) transmissions. --------------------- Date: Mon, 14 Jan 2008 21:34:48 +0000 From: Wrambler242@xxxxxxxxxxx NIT; thicker fluid will NOT cause auto tran clutches to engage faster, rather it will slow engagement down and maycause slippage. The fluid has to leave the space between the clutches before they fully engage. That is why some clutch plates have the slotted or grooved areas in them, the grooves give space for the fluid to move to speed engagement. -- Frank Swygert Publisher, "American Motors Cars" Magazine (AMC) For all AMC enthusiasts http://farna.home.att.net/AMC.html (free download available!) _______________________________________________ Amc-list mailing list Amc-list@xxxxxxxxxxxx http://www.amc-list.com/mailman/listinfo/amc-list