My 2001 Grand Prix with the 4T65E trans. I bought it new and have done a pan drop and filter change every 30k miles since (180k miles now). It takes 7.5-8 qts to refill with a filter change, that is a pretty good % change with each service. At the 30k and 60k changes I filled it up with M1 ATF which met the Dex III spec. at the time. When I did the 90k change I pulled a sample. The viscosity of the fluid (mostly M1 ATF) was "cSt @ 100ºC 5.72"
http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=1228387
Considering it was mostly M1 ATF I was surprised how much it had sheared, to less than a new Dex VI. I've been running Dex VI since 90k. Sometime around 110k I started to have issues with the car slamming from gear to gear. It would mostly do this when running in hotter weather doing stop and go driving. It apparently is a common problem where the trans. thinks it isn't shifting fast enough (solenoid issue?) and defaults into a fail safe mode where it maxes out the pump pressure. You hear lots of pump whine and the shifting gets incredibly hard. I installed a shift kit at the 120k mile pan drop and that seemed to pretty much fix the issue. Much cheaper than dropping the trans. to replace some valves. It will occasionally shift a little more firmly when hot but never like before. More recently (last summer) it was often kicking in and out of torque converter lock-up. Another not so uncommon problem with this trans apparently. By playing with the throttle you could minimize it but it was annoying and I was concerned with the additional wear. Researching it, I found there were multiple causes. To me it felt like the computer could just not make up its mind. I disconnected the battery for an afternoon last fall and it never really did it again. Maybe slightly during the next week or so but that was many months ago and so far so good. Due to those two issues I was wondering how valuable a UOA would be since I expected some extra wear metals and debris due to those two issues. I never saw anything unusual in my pan drops, even pulling the filter apart. This weekends pan drop was no different. The pan looked very clean and the inside of the filter was very clean also.
I put in 8 qts of Redline D4 after the filter change and then flushed another 4 qts thru for a total of 12 qts of D4. I mailed my sample to Blackstone Labs today. Due to the trans. issues I'm not sure how it will compare to the previous sample sent at 90k miles but the viscosity comparison should be intersting if nothing else. How does used M1 ATF (DEXIIIh) compare in viscosity to used Dex VI out of the same vehicle? We'll see. If I have the car in another 90k miles I'll be sure and pull a sample of the D4 as well.
I'll post the UOA when I get the results. So far I cannot tell a difference in the shifting. Feels the same as always. I did leave the battery disconnected while doing the pan drop to let the computer reset and relearn with the new fluid.
http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=1228387
Considering it was mostly M1 ATF I was surprised how much it had sheared, to less than a new Dex VI. I've been running Dex VI since 90k. Sometime around 110k I started to have issues with the car slamming from gear to gear. It would mostly do this when running in hotter weather doing stop and go driving. It apparently is a common problem where the trans. thinks it isn't shifting fast enough (solenoid issue?) and defaults into a fail safe mode where it maxes out the pump pressure. You hear lots of pump whine and the shifting gets incredibly hard. I installed a shift kit at the 120k mile pan drop and that seemed to pretty much fix the issue. Much cheaper than dropping the trans. to replace some valves. It will occasionally shift a little more firmly when hot but never like before. More recently (last summer) it was often kicking in and out of torque converter lock-up. Another not so uncommon problem with this trans apparently. By playing with the throttle you could minimize it but it was annoying and I was concerned with the additional wear. Researching it, I found there were multiple causes. To me it felt like the computer could just not make up its mind. I disconnected the battery for an afternoon last fall and it never really did it again. Maybe slightly during the next week or so but that was many months ago and so far so good. Due to those two issues I was wondering how valuable a UOA would be since I expected some extra wear metals and debris due to those two issues. I never saw anything unusual in my pan drops, even pulling the filter apart. This weekends pan drop was no different. The pan looked very clean and the inside of the filter was very clean also.
I put in 8 qts of Redline D4 after the filter change and then flushed another 4 qts thru for a total of 12 qts of D4. I mailed my sample to Blackstone Labs today. Due to the trans. issues I'm not sure how it will compare to the previous sample sent at 90k miles but the viscosity comparison should be intersting if nothing else. How does used M1 ATF (DEXIIIh) compare in viscosity to used Dex VI out of the same vehicle? We'll see. If I have the car in another 90k miles I'll be sure and pull a sample of the D4 as well.
I'll post the UOA when I get the results. So far I cannot tell a difference in the shifting. Feels the same as always. I did leave the battery disconnected while doing the pan drop to let the computer reset and relearn with the new fluid.
