Hi Jeremy,

Here is my opinion...

Black fluid is not good.

The 4l30e loves fresh fluid and regular filter changes, not changing the fluid and just topping it off is asking for future problems. a slurry thick sludge will build up on the bottom of the pan and potentially clog the filter. Transmission fluid has a limited usage life and is shortened by heat caused by friction. Lubricants past their lifespan will break down and "varnish" leaving a sticky residue, potentially clogging the transmission valve bodies. If you are afraid of taking your truck to the shop to have it flushed, please consider doing the minimum and do a complete fluid and filter change. Pay careful attention when refilling with fresh fluid. Overfilling the 4l30e will cause foaming of the fluid and overheating.

Good luck! <img src="/forums/images/graemlins/smile.gif" alt="" />