Bimmerfest - BMW Forums - View Single Post - DIY - E39 525i Fluid Triple Play (PS, diff & tranny fluid change)
View Single Post
Old 02-06-2008, 12:26 AM
riro424 riro424 is offline
Officially Welcomed to the 'Fest
Location: Chicagoland
Join Date: Oct 2007
Posts: 187
Mein Auto: 2003 525i
DIY - E39 525i Fluid Triple Play (PS, diff & tranny fluid change)

This is yet another data point for the growing number of E39 owners who have replaced the "lifetime" Esso ATF. There have been a number of threads that I have learned from, so I want to give thanks to those who have already shared their experiences. The details of this DIY are specific to the 525i, so 530i and 540i owners should verify any differences before proceeding.

* If you have not done a DIY oil change, please do not try this as your first fluid change.
* If you do not have jacks, stands/ramps (nor know how to properly use them) or if your head cannot withstand the weight of 3400 lbs, please do not try this at home.
* If you do not know that a running car in a garage without proper ventilation will kill everyone inside, please do not try this at home.

After gleaning wisdom from those who have shared their ATF change experience, I decided that at 51K miles (bought my 2003 525i at 49K miles) that it was time to purge the lifetime Esso. Since I was not using fresh Esso, I decided to do an immediate second drain & refill, getting about 85% new ATF compare to just 67% with just the pan drop and refill. There are some folks who drove another 1000 miles before doing a second pan drop, filter, & refill that will get them to 90% new ATF. Either approach is preferable than keeping the lifetime Esso in the tranny.

Since the differential and PS fluid changes require only an additional hour at most, I decided that a DIY Fluid Triple Play is the way to go.

* The pictures were taken a couple days later since I did not have a clean third hand to take pictures while wrenching, cussing, screwing and moaning.
* I used the term "no visible wear" for the PS ATF and the diff oil only in visual comparison to the Esso ATF, and acknowledge that the fluids could have deteriorated.
* The times shown are estimates, not targets to beat. You are not practicing for a career at a 10-minute lube joint nor for a NASCAR pit crew slot. Take your time to do it right.

With a sunny, 50 degree forecast for Super Bowl Saturday here in central Virginia, I decided to go for it. Immediately after lunch, I took the E39 out for a 10-mile drive to get the fluids nice and hot before getting started. After getting the rear tires on the ramps, and placing jack stands on the front sides (with the jack on the front center lift point for additional support), I measured the temperature of the tranny (126 deg F) and diff (107 deg F) pans. The fluids inside would be a bit too hot to work with so it's best to start with the easiest job, replacing the PS fluid. By the way, the car should be as level as possible when placed upon jack stands/ramps.

The 525i has rack & pinion steering that uses ATF (Dexron III) instead of regular power steering fluid. The Bentley manual doesn't state the system's capacity, but given the collective knowledge of those who did the turkey baster drain/refills, one quart appears to be the magic number. The 540i has a different steering gearbox system.

Changing the PS fluid first allows the tranny and diff to cool down a little (but I didn't think of it until afterwards...I actually changed this last). Purists would want to do a complete drain before filling with fresh fluid, but that requires a lot more time and increases the risk of getting a leak in the PS system.

This process mixes new fluid with the old, but that's fine by me since it's better than not changing it. If you agree that it's OK to mix the new with the old ATF, this is probably the most simple fluid change on the E39.

Use a couple towels to cover the areas where oil is likely to drip, and you can save a couple minutes of cleaning time.

For $4 worth of ATF and an $8 suction gun, I probably save $100 compared to a dealer job. Then again, I might have extracted only new ATF the 2nd and 3rd time since there is no way to tell...

Now that my confidence is building, it's time for a slightly more difficult task of changing the differential fluid that also happens to be a magical lifetime oil. According to Bentley, it is a specially formulated synthetic gear oil (SAF-XO...cognac?) that is available through authorized BMW dealers. I picked up a filler spout with a 12" tube ($4) from Advance Auto that has a nice flow-lock device on the cap-screw. You'll need a breaker bar to get the fill/drain plugs out.

The 525i's differential has a 1 LITER (1.1 quarts) capacity, and dog-gone-it, the bottles in the US come in 1 quart size. I couldn't find M22 aluminum crush washers at the auto parts stores around here so I just reused the old ones. The lifetime diff oil didn't have any visible wear.

After torquing the plugs, use Simple Green to remove oil off the diff housing.

Well, wasn't that simple as well? Two quarts of M1 75W90 @ $9 each, $4 filler spout, $12 for the 18" breaker bar, $10 for a set of 3 large hex bits amount to a grand total of $44 for a job that a dealer might charge $150 for. The savings are adding up and paying for new tools. I even got to dust off my seldom used torque wrench for this job.

OK, my confidence is way up to the point of feeling like the 18-0 Patriots as a 14 point favorite in the Super Bowl. It is now time to do the tranny! Unlike the PS and diff fluid changes that are very straight forward, draining and dropping the tranny sump pan is quite a bit more involved.

The 525i steptronic has the ZF 5HP19 transmission (aka A5S 325Z) that is filled at the factory with a lifetime Esso ATF. If you decided to change the ATF, you probably don't believe in the tooth fairy either. To be absolutely sure that you have the 5HP19, you should check the stamped GREEN metal label on the back of the tranny. You will need a towel to wipe off the crud on the label.

I've divvied up the ATF change into two separate processes: 1) Pan drop and reinstallation, and 2) ATF fill. Having the right tools makes the pan drop job much easier. Wally carries a large rectangular oil drain pan for ~$6, and I highly recommend getting an electric screwdriver with a clutch (Black & Decker $20 @ HD). Repeat after me: I will get a high-grade T-27 socket and driver bit, and not a combo bit that will waste an hour of my time by stripping the pan bolt.

BMW parts you will need (
PN 24 34 1 423 376 - OEM Filter (Filtran) - $18.92
PN 24 10 1 423 380 - OEM Gasket (green paper) - $10.66
PN 24 10 1 423 273 - T-27 bolts with spring washer (order at least 4 extra) - <$1 each

Wait, there's more. A magnetic dish to hold (22) pan bolts will keep them from rolling throughout the garage as they are removed. The optional (in my case, mandatory) drill with a 7/32 bit and vice grip for removing stripped pan bolts.

Some of the other posts recommended the purchase of an overpriced Snap-On stubby 8mm hex. However, another benefit to owning a 525i is that there is just enough clearance to use a regular 8mm hex bit, 3/8-1/2 drive adapter, and a breaker bar. Thus, 525i owners do not have to kill themselves trying to loosen the Fill Plug with just a ratchet.

Before we get started with dropping the tranny pan, here's a quick change of scenery to get the adrenaline flowing.

I had two objectives: 1) Don't make a mess, and 2) Don't strip any of the (22) T-27 pan bolts.

In step #4, be careful in loosening the T-27 pan bolts with the ratchet. Even with great care, I ruined the T-27 socket tip, stripped two bolts, and spent an hour trying to remove them. Ultimately, I drilled them out and used a vice grip to remove the bolts. So much for a perfect 19-0.

I'm in the home stretch, and it's time to fill the tranny.

If you use jack stands in the rear of the car, keeping your foot on the brake when running the tranny through the gears will keep the wheels from spinning. Allowing the wheels to spin without a load will trigger your DSC, and more importantly, be hazardous to anyone standing around the vehicle. Keep checking for leaks around the gasket whenever you crawl under the vehicle. Tighten the bolts where you see oil seeping along the pan seal and around the pan bolts.

Since I haven't put too many miles on the car, I couldn't really tell if the tranny is performing better. However, I definitely feel better knowing that I no longer have gray Esso and filthy magnets in the tranny. For less than $80 in fluids/parts and $150 worth of new tools in my garage, I easily saved $400-700 on the ATF change and knowing that I did the job properly. Well, that's all folks, and enjoy the Bean in Chicago's Millennium Park!

Last edited by riro424; 02-06-2008 at 12:45 AM.
Reply With Quote