Just curious for some opinions. I was going to do a pan drain/refill in the big 6L90E trans crammed into my CTS-V. She has 41,000 miles on her. I have a ton of the pre-Dex6 Mobil 1 ATF I'd like to use up. As far as I can tell a drain and fill will net me about a 50% replenishment.
Pretty easy to say "oh it specs this only" The most reputable performance rebuilder of the sister transmission, the 6L80E, uses Dex III in their rebuilds because they see no benefit from Dex6, only added cost and lower viscosity.
Pretty easy to say "oh it specs this only" The most reputable performance rebuilder of the sister transmission, the 6L80E, uses Dex III in their rebuilds because they see no benefit from Dex6, only added cost and lower viscosity.