john50

I'm doing my fluid changes and service based on mileage, and not on the on-board computer. Call me conservative, but I don't trust the computer to tell me how much anti-wear additive I have left in my engine oil, when it doesn't ask me if I'm using Shell or Mobil. I know the two companies too well to accept that they're blending with the same components or safety margins.

So I just changed my rear differential fluid at 15,000 miles this morning. It seemed really odd to be using Honda ATF fluid in an application that takes gear oil in almost all other Honda/Acura applications.

But I can't find any reference anywhere (official or not) that says I should change my transmission flulid already, even as a "break in" change.

The ATF out of the differential was nice and clear, with no apparent oxidation or particle contamination. And there were no metal particles on the magnetized drain plug.

So should I worry about going ahead and changing the transmission flulid?

XLR8R

Unlike most differentials, where gear oil simply splashes around and keeps the gears wet, the SH-AWD has wet clutch packs in the side cases. These operate with high friction and obviously, high temps. The ATF-Z1 has lower lubricity for the clutches and does a good job managing heat.

Honda usually calls for the first change at 60k. Monitor the fluid. At 15k it should still be cherry red. As long as it has some red color, does not smell burned and a drop spreads nicely on a paper towel, the ATF should be serviceable.

I change mine at 30k with two drain/fill sequences to get a good exchange.

Khanyam3

Is there a DIY for differential fluid change?

john50

I haven't seen a DIY, but I watched my mechanic do the fluid change.

Quite simple, although the drain and fill plugs were in quite tight. I'm glad he was loosening them, and not me. He did take the precaution of loosening the fill plug first, and then the drain plug, to make sure he could refill the case after he'd drained it.

There is actually a hole in the cross member directly behind the differential, so you can insert your ratchet extention through the cross member, and get at the drain plug.

So loosen, the fill plug, loosen and remove the drain plug. Drain, and refill until fluid just starts to flow back out of the fill line. I always replace the crush washers, and torque to specs.

He also noticed that someone had loosened the drain and fill lines since the vehicle left the factory. The painted marks on the plug didn't line up.

I' bought the vehicle new, with 6 miles on the odometer.

Khanyam3

John the differential fluid is part of the A16 service right? Do you know how much the dealership charge for a differential fluid change?

MMike1981

theres quite a range...

Honda dealers may be a few lower, expect 130-150 range (A16 is oil AND rear diff) I also checked with a few independent service places price is from 8-120

Acura dealers cheapest ive seen is 150 and can get as high as 250
Where i live i was quoted and paid 170, another dealer wanted 250 told them they were absolutely crazy.

so find a decent price, but also check for service coupons

JGard

Wow, I'm glad I read this. I was going with conventional wisdom and ready to put some 75W-90 Mobil 1 into the rear diff. Looks like it's time to go back to Autozone for some ATF. ugh.

IntegraVT

iTrader: (1)

JGard, if you're going to AZ for ATF on this application make sure it lists ATF-Z1 equivalent on the bottle. IIRC, Castrol Import Multi-Vehicle ATF is one.

But I'd go with the Honda stuff given a choice... At least in my area, the price difference between Castrol IMV ATF and real ATF-Z1 is nil. Granted, I may be a little gunshy having owned a bum 01 CL-S tranny and a VTM-4 G1 MDX, for which no alternative differential fluid exists...but as XLR8R mentioned, we do not have traditional differentials.

JGard

gotcha... I got Mobil 1 ATF before checking anything, and only two quarts of it (as most diffs in my experience take less than 1 quart). So I'm WAY off. I'll try Autozone and then I have to go elsewhere to find a decent pumping canister. The one I have is TINY...it would take me 3 hours to refill the diff. Fun fun!

JGard

well, I just filled it with that Castrol Import Multi-Vehicle. I wouldn't really know where to go to get the Honda oil, except maybe the dealership, and that's not really happening. We'll see how she holds up!

mobileworks

does anyone knows how many quarts of atf fluid does the tranny takes??? Pls help.. thanks in advances

Samdog-1

It holds just over 8 qts, but you can only drain about 3.5 to 4. The rest is in the torque converter.

littleblazer

Here is the right way to flush the transmission.
TRANSMISSION FLUID FLUSH PROCEDURE
2007 ACURA RDX 2.3L L4 DOHC i-VTEC (K23A1) TRANSMISSION

PROCEDURE:
Automatic Transmission Fluid Flush.

Description:
Acura Approved Transmission Flush Procedure.
Requires 12 quarts of Honda ATF-Z1 Fluid.
Techs in the field advise using only Honda ATF-Z1 in Honda and Acura transmissions. Apparently, other fluids will cause harsher shifting characteristics noticeable to the customer.

Procedure:
1. Set the parking brake, and raise the vehicle on a lift.
2. Drain the trans, and refill it with Acura Precision Crafted ATF-Z1.
3. Start the engine, shift into Drive, and release the parking brake.
4. Push down on the accelerator pedal to raise the vehicle speed to 2,500 rpm.
If the trans shifts past 2nd gear, go to step 5.
If the trans won' t shift past 2nd gear, keep the engine speed at 2,500 rpm and shift from Drive to Neutral and back to Drive. Then go to step 5.
5. Make sure that the trans shifts through all the forward gears and goes into torque converter lockup.
6. Let off the accelerator pedal, and press the brake pedal to drop the vehicle speed to zero. Shift into Reverse and then into Neutral.
7. Shift into Drive, and repeat steps 4 thru 6 four more times.
8. Set the parking brake, and repeat steps 2 thru 6 two more times.
9. Drain the trans, and reinstall the drain plug with a new sealing washer.
10. Refill the A/T with ATF-Z1.

cwepruk

Good info. Alternately, a person could just drain, fill, drive for a while (a day?), then drain, fill.

Is there a filter to change?

littleblazer

No Filter

cwepruk

Is there an simple drain and full plug? If so, them seems life a no brainer for DIYers. Drain, fill, drive, drain, fill.

horsepoop

Silly question but between drain, fill, drives would you replace the drain plug with the old washer or use the new one? I would think you would only use a new washer during the last drain and fill right? Thx!

wspy

Best thing would be to use a new one but the old can be reused.

diggerdave38

Is the Castrol Import Multi-Vehicle OK for the rear differential? I hope so; I changed mine at about 25k miles and used the Castrol.

I had to use a rented torque wrench to loosen the bolts, and when I got them off there weren't any crush washers. I got a set of washers for the job, but the parts guy gave me the wrong sizes, so I had to replace the bolts with no washers. I'll have a fun time removing those buggers next time.

vash337

good info here. just bought an 07 w/ 37k on it and was looking into maint. stuff

mau108

Has anyone done a transmission drain and fill? How do you fill it on the RDX?

On my other honda's the dipstick hole was big enough to fit a long funnel and fill, the dipstick hole on the RDX is the size of a engine oil dipstick which a normal funnel won't fit (maybe not mine, I'll have to check the auto store to see if they have funnels with a smaller tip)

fryrice

bump for answers

VietNinjaJ30A1

I remember seeing a DIY thread (or maybe it was just a FYI thread) where someone changed the differential fluid. I assume they would've changed the transmission fluid as well.