DIY: Transmission Oil Change

spearfish25

Ok, here is the DIY 6MT Transmission Oil Change that I was promising.

***THIS IS FOR MANUAL TRANSMISSIONS***

The following is how to change your 6MT TRANSMISSION OIL. Automatics may be similar, but you should substitute appropriate automatic transmission oil and reference the service manual to make sure there aren't subtle differences.

Required items:
Jack and jack stands
Torque wrench
10mm Allen head ratchet attachment
Nissan metal gasket x 2 (38351B) http://www.courtesyparts.com/38351b-...-p-618030.html
Siphon pump (available at Autozone for $10)
Manual transmission oil, 3 quarts (I used Redline, 50:50 blend of MTL and MT-90. UPDATE***Redline also has a new MT-85 fluid which is specific for the Z. You can use MT-85 without blending.)
Oil collection pan or container (Autozone $10)
Gloves (you don't want this oil on your skin)

Instructions:

1. For this oil change, I'd recommend getting the car off the ground completely with either 4 jack stands or a lift. The transmission is very centrally located and has a long length. To best access and empty the whole tranny, a 4 point lift with either jack stands or a true lift is ideal.

2. Allow the car to cool so you don't burn yourself when you drain the oil. The transmission is the large unpainted aluminum component located in the midline of the car roughly below the shifter inside the vehicle. There are no covers or plastic pieces that need removal, so access is easy once you have the car up. Place the oil collection pan under the tranny and locate the FILLER screw first. This is on the passenger side of the transmission and is a round screw that requires the 10mm allen head ratchet attachment. Break this screw loose before you drain the tranny to ensure you can refill it.

3. Once the filler screw is loose, go ahead and remove the drain screw. This is identical to the filler screw and is clearly visible on the bottom of the transmission. I broke it loose with the ratchet and then loosened it the rest of the way with the allen attachment by hand to make sure I didn't drop the screw into my oil collection drum. Make sure you have your gloves on because you'll get some on your hands once the screw is nearly completely out.

4. Allow the tranny oil to empty completely...give it 10 minutes or so. You'll see that unlike the rear differential oil, it looks rather pristine.

5. Once the oil is drained, place a new metal gasket on the drain screw and screw it back in place. The recommended torque is 25 ft-lbs.

6. Next remove the filler screw on the passenger side of the tranny (you may have done this already in a previous step). This will give you access for the siphon pump hose. Insert the outlet end of the siphon pump into the tranny a few inches so it stays in place.

7. Place the inlet hose of the siphon pump into your fresh container of oil. Start pumping...you'll notice it takes a bit of work to pump the viscous oil up into the transmission. The capacity is 3 quarts and I used a 50:50 blend of MTL and MT-90 since I live in Chicago and experience the hot and cold extremes. The mix will get you a blended viscosity close to Nissan's recommendation of 75w85 (MTL is 70w80 and MT-90 is 75w90). Pump until oil starts leaking around the pump hose from the filler screw hole.

8. Once the tranny is overflowing, you're all set. Remove the siphon hose and place a new metal gasket on the filler screw. Replace the filler screw and torque it to 25 ft-lbs.

9. Clean up the mess and check for leaks.

While the difference is subtle, I do think the shifter action is a bit smoother especially when the tranny is cold. I'll have a better sense over the next few days.

You've now changed your transmission oil...check out the rear differential oil change in the DIY section as well. Having seen the character of both factory oils, I'd recommend the rear diff oil change for sure. The tranny is more optional as the oil looked very clean at 4000mi.

If you've found this helpful, feel free to give a +rep

Modshack

Just a simple warning....Always remove, or at least loosen, the fill plug FIRST. Nothing worse than having drained your fluids and then not being able to get the new stuff in caust the fill plug is stuck, cross-threaded, or otherwise unwilling to come out etc !

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spearfish25

Yep, that point can't be stressed enough. Emptying your tranny or diff without being able to refill it would be a doozy.

One other important safety practice is to complete one task at a time. For example, I had the car up on a lift to do the tranny oil change. I changed the engine oil at the same time. While it would have been faster to empty both, refill the tranny and then drop the car to refill the engine oil, that is a risky practice. It's easy to forget you haven't refilled the engine oil, fire up the car and....oops.

spearfish25

Update: the transmission shifts much more smoothly now when it's cold (70-80F) weather. Once it's warm, it feels about the same. Essentially shifts when cold feel as if the tranny is already warmed up now. Definitely worth the oil change.

edeeZee

What's the interval? Because you must drive a lot to have to do this already.

davidyan

^ I think he's just trying to switch out to a synthetic MT fluid. Some have found it to make the gearbox a little smoother. If you don't want to do that, typically its switched out at about 30,000 miles or 15,000 under more severe driving conditions.

spearfish25

^bingo. It was worth the early swap with the better cold shifting performance.

pookienachos

guys, where do i refill the Automatic Transmission Fluid? cant find it and its not in the manual. many thanks

davidyan

Most AT's are refilled from the AT dipstick. Should be the red handled one leading to the transmission.

pookienachos

can you please show me a pic. cant find it. thanks

schrute

Did my fluid swap using your DIY, Thanks and Rep added! Just wanted to agree with the improvement in shifting when cold. Before the change to Redline fluids my first shift into first in the morning was stiff compared to when things warmed up. Not anymore - feels great right from the getgo.

Edit: Shouldn't this DIY be a Sticky alongside Spearfish's otherDIY that is a Sticky for the Diff fluid change? Just a thought.

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spearfish25

Thanks, Schrute. Glad the DIYs were helpful.

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TipsZ

I noticed that you stated that you used a "50:50 blend of MTL and MT-90 since I live in Chicago and experience the hot and cold extremes". So, what weight would you recommend for Florida?

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spearfish25

You'd be fine with the MT-90 alone.

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vipor

sweet. thanks for the in-depth write up got my first track day feb 6th and i'm hoping to be able to take the time to swap my tranny and diff fluid as well as add an oil cooler

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