Transmission Fluid Recommendation

[Trailrunner Lance]

I just picked up a 2003 Tahoe Z71 with 184K. Runs good and appears to be well taken care of but I have no service records. I plan to take to my mechanic Thursday to drain the transmission fluid and replace the filter.

My mechanic doesn't recommend using a full synthetic ATF. I had planned to use Mobil ATF and have read where alot of Chevy users also use it (Mobile full synthetic).
Mechanic says if it always used conventional ATF stay with it and that synthetic eats the seals.

I'm open to hearing what other owners recommend.

 

[Bimmersixx]

Not sure about synthetic ATF, but about a month ago I had the transmission in my '04 Z71 flushed and the fluid replaced and I can definitely tell a difference. Drives great and very smooth. Best $130 I ever spent - totally worth it. Make sure you get the flush/replace. You can't just drain a transmission completely by dropping the pan.