Just got the analysis on my ATF from the car in my sig. Here's a quick history:
Winter of 2016 at around 168k miles it got the first drain and fill it had seen in a while. Fluid was brown, stinky, and overdue. I didn't sample at the time...and I'd be somewhat afraid to see how bad it was. Decent amount of fuzz on magnet but all super fine sludge with no chunks. Fluid didn't feel noticeably gritty and didn't show any "glitter" in the drain pan. No filter to change - just a permanent internal rock catcher screen. I put in 3.5 quarts of Pennzoil generic Dex/Merc. Greatly reduced harsh shifting, but did not eliminate it.
Summer of 2017 at around 172k miles it got two more D&F. First with generic Dex/Merc, and the second with Valvoline Maxlife and red bottle Lubegard. Fluid came out dark red-brown but didn't smell as bad, had no gritty feeling, and magnet had only a small layer of fine sludge. I added a transmission temperature gauge at the hot line to the cooler to keep an eye on it since I knew I was in for some hard, hot miles.
I then took it on a road trip to the west coast and back and drove it all fall and winter for my commute. Shifting really smoothed out over time until it was shifting like new. Max temp I saw on the gauge was 115C /239 F, but only for a minute before I downshifted to let it cool off. Temps generally ran between 75C / 167F and 100C / 212F.
At the beginning of the month at 186,600 miles I did another D&F with Maxlife when I rebuilt the cooler lines and added an external cooler. That's when I took a sample with about 14.5k miles on the fluid. Fluid was dull red, felt slippery, and smelled just like the fresh Maxlife (you'll know what I mean if you used that stuff). Small amount of fine sludge on magnet, with no chunks.
I'm hoping the high iron, aluminum, and insolubles are biased up from 10-15% of the really old fluid that remained after the three D&F, and from cleaning action of the new fluid picking up deposits. I'll be doing a another drain and fill in a few hundred miles, which should have all but a couple percent of the old fluid removed. Next year I'll sample it again, which will probably be close to their recommended 15k miles.
Winter of 2016 at around 168k miles it got the first drain and fill it had seen in a while. Fluid was brown, stinky, and overdue. I didn't sample at the time...and I'd be somewhat afraid to see how bad it was. Decent amount of fuzz on magnet but all super fine sludge with no chunks. Fluid didn't feel noticeably gritty and didn't show any "glitter" in the drain pan. No filter to change - just a permanent internal rock catcher screen. I put in 3.5 quarts of Pennzoil generic Dex/Merc. Greatly reduced harsh shifting, but did not eliminate it.
Summer of 2017 at around 172k miles it got two more D&F. First with generic Dex/Merc, and the second with Valvoline Maxlife and red bottle Lubegard. Fluid came out dark red-brown but didn't smell as bad, had no gritty feeling, and magnet had only a small layer of fine sludge. I added a transmission temperature gauge at the hot line to the cooler to keep an eye on it since I knew I was in for some hard, hot miles.
I then took it on a road trip to the west coast and back and drove it all fall and winter for my commute. Shifting really smoothed out over time until it was shifting like new. Max temp I saw on the gauge was 115C /239 F, but only for a minute before I downshifted to let it cool off. Temps generally ran between 75C / 167F and 100C / 212F.
At the beginning of the month at 186,600 miles I did another D&F with Maxlife when I rebuilt the cooler lines and added an external cooler. That's when I took a sample with about 14.5k miles on the fluid. Fluid was dull red, felt slippery, and smelled just like the fresh Maxlife (you'll know what I mean if you used that stuff). Small amount of fine sludge on magnet, with no chunks.
I'm hoping the high iron, aluminum, and insolubles are biased up from 10-15% of the really old fluid that remained after the three D&F, and from cleaning action of the new fluid picking up deposits. I'll be doing a another drain and fill in a few hundred miles, which should have all but a couple percent of the old fluid removed. Next year I'll sample it again, which will probably be close to their recommended 15k miles.