Amsoil ATF, 10k miles, 04 Tahoe

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Aug 29, 2011
Apparently blackstone didn't have the right category for my AT, so originally I thought all of the wear metals were on-par with averages. We bought this one at 122k miles and not knowing the history did a pan drop only and replaced with Amsoil ATF. I think next round I'll do a full flush/fill but not sure if I want to go back with the Amsoil ATF or their ATL product. Any suggestions? (Wife's daily driver, no towing, mostly in-town driving)
We bought this one at 122k miles and not knowing the history did a pan drop only and replaced with Amsoil ATF.
Lots of old fluid contamination in the new fluid. Who knows how high the wear metals were in the old fluid and how it effected the new fluid. IMO nothing valid enough in these results to either praise or condemn the Amsoil ATF.
Originally Posted By: Pablo
Full flush or a UOA is rather pointless. Just looks like you diluted the previous fill a bit.
Yup, mfrs usually say flush for a reason.
Either do a proper flush or do drain n fills every 100 miles until the concentration of old - new fluid is as close to 100% new fluid as possible (usually takes 3-4 drain n fills with most transmissions, from what i've seen from personal experience) I also wouldn't bother with the UOA. It doesn't show much, esp on an older, used vehicle. It could have a ton of accumulated wear metals from years ago.
I elected to do the flush only based on the advice of the local trans shop. They were concerned with the unknown history that doing a flush could release too many solids and clog the filter. Also keep in mind the first UOA I got back showed all wear metals were well within normal range, the only thing flagged was the viscosity had dropped too low (based on my AT being miscategorized). It wasn't until my first check in at 10k that the change in category meant the wear numbers were too high. I elected to go the ATF/DexIII option. Call me a skeptic but I haven't seen a lot of history on the Dex VI fluid nor many UOA's to know if the low viscosity fluid can really hold up as long as the Dex III. The risk in my mind outweighed any possible gain in MPG.
The DexronVI fluids have better viscosity and friction modification retention than does DexIII. I use it in both of my vehicles, an '08 TrailBlazer (with 5.3L V8) and my 03 Nissan PathFinder.
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