What you saw was completely normal. What you probably should do is, wear safety glasses, get a pressure pump and pump in from that filler plug. You need to either find a prefect fit or at least very snug fit, otherwise, you're gonna see that oil gushing out from that port again.

Once you pump the fluid back in there with the engine shut off, you can only put in around 3 qt, if I recall it correctly. The last missing qt you'll have to pump in while engine is on.

The gushing only happens for the first 5 seconds or so after you start the engine. If you have a snug fit, there won't be any oil spilling out, and you can pump that missing 1 qt back in there while shifting around.

Good Luck!

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01' 3.0i E53 (M54) with 164,000 miles
07' 3.0si E83 (N52) with 134,000 miles
08' 3.0si E70 (N52) with 91,000 miles