oldskewel AT 170K without a fuel filter replacement did you notice any issue? or since changing have filter you noticed any change? up in mpg or more responsive when you hit the pedal?

No problems before or after. No change noticed. A good amount of black oily stuff came out of the filter when I drained it, but I expect I could have run many more miles before doing this. I think the fuel filter change interval is highly dependent on the fuel quality. If using clean fuel you might never need to change it, but if dirty fuel it could be fairly often.

BTW, same thing (first time maintenance at 170k miles, with no problems before or after) on spark plugs (yes, original at 170k with no problems!) and upstream O2 sensors.

First time change on AT fluid (twice) and front diff oil, with noticeable improvement.

The car really seems perfect now and I've run out of things to do on it.

Can you elaborate on the improvement? How was the old fluid in the trans and diff?

First time change on AT fluid (twice) and front diff oil, with noticeable improvement.
The ATF was ridiculous. Looked like a black soup of microscopic particles. Certainly original. New filter, cleaned pan, drained overnight to remove 7 qts total. Replaced with Dexron VI, which is the current spec for the A5S 390R in my 2001 3.0i.

It immediately felt like the car had less drag, shifting much smoother and faster. For example, prior to the change I did not find the steptronic shifting responsive enough to use comfortably, so I never did. I do now (just for fun). I can now feel it quickly and smoothly shift through each gear on all types of acceleration.

I drove like a granny for a few hundred miles, concerned with the stories of some gunk breaking loose, getting stuck in the wrong place, and having the AT destroy itself. I figured if something were to break loose and I was driving gently, there'd be more chance for things to sort themselves out before catastrophic damage.

Since the fluid was so bad, I did another change (new filter, 7 qts Dexron VI) after 400 miles. The fluid was not quite so bad, but still so dirty that I'm glad I changed it. The capacity is spec'ed at 9.5, so in theory there was only 2.5 qts of the original dirty oil, but I guess that's a lot if it is really dirty. The pan was not so full of fine particulate debris this time, but I did find one pea-sized glob of goop sitting on the pan. I also found one shard of a gear tooth (had found none in the first change) - but it was tiny - about 2mm long and seriously only about 0.1mm diameter - would have been invisible except it was very shiny. So this supports the legend of new fluid shaking loose dangerous goop, but I survived.

Driving maybe improved a little more following this change, but not as dramatic as the original one. 500 miles since the second change. I'm actually considering doing a 3rd one later this year - very cheap to do with Dexron VI, and now that I've figured out how to do it carefully.

Front diff oil - that looked black too, with just a couple of shiny flakes. I expect it was original just based on the overall philosophy of the PO. Also, the rear diff oil was dirty, but noticeably cleaner, which makes sense because that is much easier to change - he probably had it changed at jiffy lube or something once. Performance - the only thing I can say there is that I remember driving the car home after buying it and could hear some front drive train noise (I figured it was normal) at freeway speed, and now I don't hear anything like that.

Thanks for the update.

when I changed my ATF fluid at 90k miles, the shifting turned to butter. it wasnt very noticable before, but after replacing the fluid it was suuuuper smooth. I plan on changing the fluid / filter every 30k mile. cheap insurance IMO

Oldskewel thanks for feedback…we had a problem out here with a couple of gas stations that were literally watering down fuel ! ‘ they’ the gas company franchises in essence are govt backed cartels where they fix prices in their own favour and NOBODY does jack, when fuel prices globally rise the prices at pumps rocket immediately! When fuel prices drop globally do pump price drop immediately?!!! nooooo ‘they’ claim they have still got older more expensive stock that has to go first…place if rife with corruption if you ask me…and goes all the way to the top
As for fuel cleanliness perhaps adding a fuel additive /complete fuel system cleaner type job in a full tank now and again won’t do any harm will it?

Hey all, thanks for the great input on this thread. And Acaman thanks for the great photos, this helped immensely. I have two X5s, both are E53s. One is a 4.4 with 155K miles and the other is a 4.6is with 125K. I had recently posted about the wifes 4.4 fuel sending unit which then inspired me to do a fuel filter change. Bad batch of gas maybe, who knows but did it on more of preventative maintenance thought.

Getting the freaking pan off on the 4.6 to expose the fuel filter was a major PIA. So word to the wise there are two 8mm hex heads right in front of the left rear wheel that need to come off. This lets you open a small flap that exposes one of the 12 - 12mm hex heads that need to come off. You will need a 6" extension with a swivel on it to remove this bolt. If you study Amacmans diagram quoted here, it will save lots of time getting this pan off.

A couple of other thoughts I would like to share is that having a FIRE EXTINGUISHER on hand is imperative. Even with pulling fuse 47, the 4.6 did not leak much gas at all but would be enough to ignite a fire if you have a hot trouble light exposed. The 4.4 even though I released the pressure by running it out of fuel, it spewed everywhere. It might be good to throw down some cardboard to catch all the dirt that will inevitably drop out of the pan.

I was able to get the fuel line fasteners undone but had to use a small pair of water pump pliers to squeeze the two ends enough to release two of the fittings on the 4.4. This made the job much easier. If you go this route make sure you squeeze with one blade of the pliers on the flat part of the fitting and the other 180 degrees opposite lightly as not to break the little blue clips. :beerchug:

I also wrote a DIY if you want to search for it...

Thanks CN90.

I have done so much reading and research the last few weeks I can't remember what I have read.

Today I changed fuel filters on both, installed a new MAF on the 4.6. For some crazy a$$ reason the thing short circuits MAFs if you get into the throttle hard. (I have a Dinan CAI). A friend drove it a couple of weeks ago and got into it pretty hard and sure enough it threw a P0120 (it think that;s what it was) code. I found a new Bosch MAF from AIP Electronics for $40. I searched the web and could not find one for under $100 bucks. Code has gone away and not come back.