[ACTX]

Hey Butterbar. First of all, thank you for you service if you are or were indeed serving.

Car drove different because of a higher-weight oil? �� Anything is possible, I suppose. Not probable but theoretically possible. Won't argue that point.

Since you now take your SA's word for everything (which is a good idea, BTW) now go back and ask him how often to change your transfer case oil, then please come back and let me know.

Or, alternatively, post a link to an ->official BMW<- site anywhere that recommends changing it.

When you do change it, let me know how it went jacking the car up, then, depending on model, possibly removing any or all of the following: the heat shields, cross braces, and, possibly, the ENTIRE exhaust system. Then, of course, you're going to need to reset the ECU using a scanner tool. If your vehicle is still under warranty and you have any drive train or exhaust problems, from the engine on back, let me know how it goes with BMW service when they tell you your warranty is null and void. They'll know from looking at the diagnostic readout or just a glance at the undercarriage.

Also, when you go into Launch Control to impress your family and friends, and your hear a massive crunch and clatter and the car jangles to a stop, take a pic of the transmission and transfer case parts scattered along the road back behind your car. That is a real risk. Or it may just suffer a lesser failure and cost you out the yin-yang to repair or replace.

One of my amigos is a certified (and associate degreed) automotive tech and for him the saddest and stupidest repairs he has to make are within a few thousand miles of a DIY transfer case muck about. He'll tell the customer "Why don't you go over and talk to the dealership manager about a trade-in?"


Anyhoo best o' luck to you.

EDIT: Oh, and I forgot. Some models don't have a drain plug, you will need to get a siphon hose to put through the fill hole to get the old oil out. And if you don't get it all (highly probable) and fill with a different oil so there is a mix? That ain't gonna be good. As absurd as it sounds, sometimes the transfer case has to be removed and turned upside down to drain all the oil. That is not a joke.