DIY: Transmission Oil Change
 

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 :)

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 !

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.

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.

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

^ 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.

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

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

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

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

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.

Thanks, Schrute. Glad the DIYs were helpful.

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?

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

sweet. thanks for the in-depth write up :tiphat: 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 :tup:

I'd suggest maintaining use of the 50/50 blend of Redline MTL and MT90. Why? Because Nissan technical specs still call for a 75w85 lubricant for maximum performance in any climate. Keep documentation of your use of this synthetic combo, as this will maintain not only your tranny, but also your warranty! :tup:

When I filled up the tranny it didn't overfill like you stated. I was a bit concerned since I did spill some of it (1/8 of a quart) when I missed the fill hole. Also, when I jacked up the car it was from the passenger side alone. Should put another quart and fill till it flows over it or will it be fine?

It didn't overflow because you didn't have the car jacked up level. I wouldn't worry. Just fill it to factory levels and you should be alright!

Thanks Steve! :tup: +1

No problem!

When I changed my transmission fluid I only jacked the front of the car up, so I didn't get any overflow either. Just make sure you compensate for some of the fluid left over in the bottom of your bottles and any residual amounts left in your pump. I think the car takes ~3 quarts so I went ahead and opened 4 -- 3 full quarts and a little bit of the 4th.

Yea, I mean the Z is running fine and the shifts are smooth but I'll go ahead and follow in your foot steps and get the 4th quart and use a 1/4 of it.

That should work out. I think between spillage and residual fluid I left behind around 1/4-1/6 quarts.

I'm amazed you guys can estimate how much is left in your pumps. The Autozone pump is an absolute POS and a complete mess. For next time, I think I'm going to get a Motive fluid transfer pump. Over the life of my car, it's worth the $60.

Just changed my transmission oil today. I used 2 blitz rhino ramps to lift up the front wheels then I used 2 jack stands to lift up the back wheels (4 point lift). I got underneath the Z very easily with that set up.

I also used measuring buckets to make sure I was putting in the right amount transmission oil (3 quarts).

Similar to these (can be found in paint section at home improvement stores, I got mine at LOWES for $2.50):

http://www.concretesolutions.com/Car...rBucketsLG.jpg

Shifting does feel smoother throughout however I can really feel the difference going into 1st and 2nd gear the most.

Thanks again Spearfish!

^ :tup:

quick question: if I was running whatever stock oil was in the tranny before, should I flush it before using redline oil? Or it prob wont matter I am guessing? (I have a manual tranny btw)

Theres no need to flush. Just drain all the fluid out, close up the drain plug and pour the new stuff in.

ok, thanks! that's what I figured...I would prefer to not flush it imo

Someone pointed out earlier that they could not find the dipstick for the transmission fluid in the automatic. I'm having the same problem. Any help?

Thanks.

Someone pointed out earlier that they could not find the dipstick for the transmission fluid in the automatic. I'm having the same problem. Any help?

Thanks.

I think that it is a sealed tranny, you don't check it or add to it. It has to be flushed and filled, but I am not a positive. But I'm sure some one else must have done this already?

Did anyone notice that RedLine had a Tranny fluid made for the 350 and the 370 now... Is this new???

Yep, new. They essentially did a blend of the MTL and MT-90 to get the desired viscosity. In my DIY (1st post), you'll see I mixed MTL and MT-90 to get the same effect.

Cool thanks... Just in time for me to do the change LOL. Now only if they did this with the rer diff as well.

The rear diff is easy...just use the 75w90 G-5 gear oil. No need to mix anything.

http://www.the370z.com/diy-section-d...il-change.html

I have checked out your DIY and its really helpful. I ment it would be nice if they came out with 80W-90 Diff fluid like it recommends in the manual.

Gotcha. I wouldn't worry about it. 75 vs 80 is insignificant.

Where can I get it? What's the weight?

Z1 motorsports sold me 3 quarts of MT90 for my 6mt, but also warned me they didn't recommend it. That previous 350z owners had complained about a harsh sound that eventually came from the tranny. Spear, you mixed MT90 with MTL you say? I wonder why Z1 is selling MT90 if there is a new blend out?

Yep, 50:50 blend. Just buy the new stuff from Redline directly to simplify things. That's what I'll do next time. However, the tranny oil stays so clean, I'm not going to swap it until the next scheduled interval in the manual. The rear diff is a different story. You can feel it dying every time you change the oil and see that crap that comes out.

Is MT-85 75W85 GL-4 Gear Oil what you are talking about?

If not can someone post a link please?