[Itogliano]

Just put new TC and diff fluid in the car since I just crossed 100,000 mi and I could swear the car feels a lot smoother driving. Is this something that would make sense I’d be able to feel or is it likely just a (purely) placebo effect?

[johnung]

Originally Posted by Itogliano

Just put new TC and diff fluid in the car since I just crossed 100,000 mi and I could swear the car feels a lot smoother driving. Is this something that would make sense I’d be able to feel or is it likely just a (purely) placebo effect?

IMO not a placebo. I would actually replace those fluids every 30k-50k. It’s simple and inexpensive. Make sure to do front and rear differentials. And do the transmission service now too. That’s normally every 60k miles

[Itogliano]

Originally Posted by johnung

IMO not a placebo. I would actually replace those fluids every 30k-50k. It’s simple and inexpensive. Make sure to do front and rear differentials. And do the transmission service now too. That’s normally every 60k miles

Yeah I meant to do them earlier and they just got away from me. Just took it to my mechanic, didn’t want to bother with the transfer case and figured they might as well do diffs while in there. Book time estimate was $1100, they did it faster though and it came out to $600, so not super expensive but not the cheapest thing in the world. Had the trans fluid done at 90k

[johnung]

Originally Posted by Itogliano

Yeah I meant to do them earlier and they just got away from me. Just took it to my mechanic, didn’t want to bother with the transfer case and figured they might as well do diffs while in there. Book time estimate was $1100, they did it faster though and it came out to $600, so not super expensive but not the cheapest thing in the world. Had the trans fluid done at 90k

Book rates are such a ripoff. They just keep increasing the book hours and at the same time keep increasing their shop’s hourly rate. So the actual cost of some jobs just becomes absurd for what they are doing.

I always get all three fluids done at the same time. The labor savings is huge to pull the car in once and do all three simultaneously. Maybe two hours-tops!

All three only take 1 bottle so it’s not expensive. Front diff is a 1/2 liter, the other two are only 1 liter.

Front differential has a drain plug. Transfer Case and Rear Differential are suctioned out through the fill hole.

Note: TC requires a thin suction tip because there are lots of things in the way inside the TC so the tip has to be moved around to remove as much old fluid as possible. About 2/3 of a liter is the most you’ll get out which is fine.

Cost of Fluids:
IMO for expensive components that require one bottle of fluid, why would I cheap out with generic fluid or believe some specialty fluid marketing claims? Why risk an expensive thousands of dollars replacement over saving a few bucks on a bottle of fluid?

Dealer list price for my three Genuine BMW fluids is $161.84. Online GetBMWParts (an actual BMW dealer in Maryland) sells the same for $127.43 + shipping. FCP Euro sells the three for $165.77- more than dealer list!

NOTE: It’s very important to know the actual Genuine BMW list price. GetBMWParts website is my reference because they publish the real dealer list price. Many BMW dealers jack up parts prices over list. And don’t assume that FCP Euro is providing a good price. They jack up many prices to pay for their lifetime warranty. Some people will take things to the Nth degree by collecting old fluid and paying to ship it back to FCP Euro. I’m not one of them so the FCP warranty is not a factor for me, only the actual price that I’m paying for fluid.

FCP does have a deal on TC fluid because they sell the actual European S-Tech fluid made by Shell for $30.99 vs $57.55 list. Supposed to be the same fluid that BMW puts the Genuine label on and marks up.

So I buy the three fluids for roughly $150 including tax and any shipping, and take them to my local independent BMW shop that charges about $250 for two hours labor.

Automatic Transmission service is more costly for 7 liters of fluid, trans pan/filter/bolt kit and special procedure that takes 2-3 hours total. ZF parts & fluid kit from FCP Euro is $212.88 for my car.

Obviously you know most of this. Just writing it out in case it helps someone..

[cfm56d7b]

Originally Posted by johnung

IMO not a placebo. I would actually replace those fluids every 30k-50k. It’s simple and inexpensive. Make sure to do front and rear differentials. And do the transmission service now too. That’s normally every 60k miles

Echoing the same. I just changed rear differential fluid at 41K miles. Transmission fluid will be changed at 50K.

[johnung]

Some good videos below to illustrate the process and the labor involved. It saves a lot of time to put the car up in the air once and do all three fluids at the same time: rear differential fluid, and if you have an XDrive, the front differential fluid and transfer case fluid.

REAR DIFFERENTIAL

FRONT DIFFERENTIAL

[nh90crxsi]

Originally Posted by johnung

IMO not a placebo. I would actually replace those fluids every 30k-50k. It’s simple and inexpensive. Make sure to do front and rear differentials. And do the transmission service now too. That’s normally every 60k miles

I will also echo this!
I love love love doing anything I can to my 340i
So maintaining my car is something I enjoy (it also saves big money cause shops continue to jack rates and add time)
And with replacement diffs and things being quite costly and the fact that we are putting well above factory power levels down I feel it’s deff something that’s done early and often!

Buy OEM diff oil, get the S tech shell transfer case fluid, a 18 dollar fluid extractor from Amazon, a 20 inch long copper nickel 3/16 brake line (to get in there real deep like) and a 3/8 threaded rod (Home Depot)coupler nut and you can get right into the transfer case w/o dropping anything to gain access.. also get new drain plugs as well

1.5 maybe 2 hours to do both diffs and transfer case working at a relaxing pace and your feeling accomplished from completing some driveline service and saving money in the process ( more mods!!!)

[Musashi]

Originally Posted by Itogliano

Just put new TC and diff fluid in the car since I just crossed 100,000 mi and I could swear the car feels a lot smoother driving. Is this something that would make sense I’d be able to feel or is it likely just a (purely) placebo effect?

A faulty TC would have shaken in turns, in slippery conditions, change in drive traction ratio (uphill etc) so no it is not a placebo. My TC rattled until replaced, it was done and then everything was ok. Cost me 7000$ and it also took with it two driveshafts. After that I learned to preserve it by not stressing the part, snow ice rain, turns, I now avoid having it alter Traction ratio.