Weird problem with a partial transmission fluid change on my X5 3.0i

[mgbmwx5]

I would just start fresh since you don't know what the PO had done, drop the pan and replace the oil filter with new pan gasket and refill properly.

Originally Posted by wellingtonamaral

I just tried a partial fluid change on my ’04 BMW X5 3.0i E53 AT, by draining from pan drain with engine off until dripping stopped, and then refilling with fresh oil via filler plug.

Issue:
I drained a little over 4.0 liters, but I’m having trouble refilling. Car is leveled. During first refill attempt (with engine off), the oil will spill back out as I pump it in (like it’s already full). Then, with the engine running (tried while both in neutral and park), when I try to unscrew the filler plug, oil sprays out with a lot of pressure. Have you all ever seen this happen?? At this point, should I move on to dropping the pan and replacing the filter and gasket, then trying again? Or should I be worry and just tow it to a shop?

Some important background:
I bought this car about 3 months ago. It has about 110 miles on it. It drove fine and felt not hard shifting or slipping at all, but I figured it was time to do at least a partial fluid change — especially considering that I don’t know much of the car’s history with previous owners. And so, I was planning on getting this done soon anyway. Bought some Pentosin ATF (5.0 Liter bottle), but before getting to it, an issue came up and prompted me to go ahead and get this done immediately. While driving, the car went into transmission failsafe. From what I gather, old fluid could be one of the many reasons the computer would trigger this restriction mode. So, before submitting myself to expensive maintenance quotes, I figured I’d go ahead with the cheapest possibility — old oil, and hence started the partial fluid change.

Partial fluid change reference:
http://www.xoutpost.com/bmw-sav-foru...hange-diy.html

Any ideas are very much appreciated!