Originally Posted by TheChronic

Here's my experience:

I did the same upgrades you're planning a couple years ago with about 70k on the clock. Changed the fluid and filter when I did them. No problems for a couple years. Decided to drain the pan and add some fresh fluid around 88k.

To my knowledge, the fluid had only been changed twice before. I did it at 50k and as said above, 70k.

The fluid I drained looked clean and new, but later that week, I lost 1st gear. I should have just paid for new clutches and a rebuild at that time 2 years ago, and probably would never have had that trouble. Because realistically, how many guys here have a factory 4L60E lasting more than 150k anyways? You gotta figure that those clutches are at least 2/3 of their way to death already. In my case, I think the old clutches were unhappy with the new fluid.