Amsoil Synchromesh is highly recommended for our manual transmissions. You can order some from XtremeRevolution in this thread: https://www.cruzetalk.com/forum/10-en...on-fluids.html
Here is a basic overview of how to change the manual transmission fluid in the M32 6-speed gearbox/transmission in the manual transmission Cruzes.
Ramps (or jack and jackstands)
8mm hex key/socket
10mm hex key/socket
10mm box-end wrench
Lots of extensions
Interior trim removal tools or flat-bladed screwdriver
2.32 quarts of synchromesh-type MT fluid (2.5 quarts is fine as well)
Latex or nitrile gloves
Beverage of choice
Time: 1 to 1.5 hours.
Skill level: Moderate. If you can barely do an oil change, this one isn't for you. If you're fairly comfortable changing oil in the Cruze AND have the tools listed, it's up to you whether or not you want to attempt this. Experienced DIY'ers should have no difficulty with this.
Fluid selection: The M32 needs a GL-4 gear oil with about a 70w-80 weight. I used Amsoil Synchromesh (MTF). Cost should be about $40-50 for 3 quarts. The Amsoil Synchromesh I used appeared to be about the same viscosity as the fluid that drained out.
My apologies about not having pictures for everything. Both cameras died on me after the MT fluid drained out.
I am posting this how-to as a service to the members. Neither I or CruzeTalk have any responsibility or liability if something bad happens. FOLLOW THIS AT YOUR OWN RISK.
0. Break free the fill plug. If you cannot open the fill plug, STOP! Get a buddy or some more tools. If you can't open the fill plug, then re-filling the transmission will get much more difficult. Not impossible, just much more difficult. The transmission can be re-filled through the level plug if you're so inclined using a fluid transfer pump like a pump-type hand soap dispenser uses. I'd recommend against this, however.
The fill plug is the quarter-sized round thing with the hex head on it.
Use the 8mm" hex bit on the long extensions to break the fill plug free. It's on there pretty well, so it will need a bit of a heave-ho to get free.
1. Get the car up in the air. I used my Rhino Ramps and drove up them.
2. Detach the under-engine panel with the 8mm socket and the flat-bladed screwdriver. There are 6 8mm screws, 6 plastic pop-out connectors, and 2 other plastic pop connectors holding the panel on. 4 screws are located at the front of the panel, while the other two are located at the back, one on each side of the oil pan cutout. There are 3 pop-out connectors on each side. One holds on the little airdam in front of the front tires. The other two attach the under-engine panel to the fenderwell skirts. Remove these and set them with the screws.
Note the two raised screw holes at the back of the panel.
If your Cruze has had the shield recall done, your shield will not look like this. Per feedback from other folks, removing the remaining shield is not needed.
3. Locate the level port. It's on the side pan of the transmission. (NOTE: This was deleted on the later 2012 and 2013+ Cruzes. Ignore this step if you have a later Cruze.)
Use the 10mm hex socket on a short extension to take it out.
4. Locate the drain port. It's underneath the differential housing, next to the subframe.
Here's the tool I cobbled together to undo the drain plug. It's the 10mm hex socket with the box end of the 10mm wrench slid over the socket. A ratchet does not have enough room to clear the subframe.
5. Make sure your drain pan is a foot to the right of the drain plug, as the fluid will shoot out in a glorious jet almost to the tire.
6. Give the drain plug a good heave-ho, as it's on there pretty well.
7. Adjust the drain pan as needed to catch the fluid.
8. Let the fluid drain.
I have no pictures after this point. All this is now is re-filling the transmission and re-assembling the underbody panel.
9. Replace the drain plug. Make this fairly snug.
10. Remove the fill plug you loosened in step 0.
11. Put your long-necked funnel into the fill port.
12. Put in 2.32-2.5 quarts of MT fluid.
13. Check to see if any fluid came out the level port. Wipe up any spilled fluid.
14. Replace the fill plug. Snug down until it stops, and do not tighten further.
15. Replace the level plug.
16. Replace the underbody panel, ensuring that all the screws and the 6 pop-out connectors go back.
17. Drive the car down the ramps.
18. Enjoy a smoother-shifting transmission!
Edited Note: GM factory fills 1.6-1.9 quarts of the transmission, but reports have been coming in that dealers re-fill 2.25 quarts. Most Cruze owners are now filling 2.5 quarts to help prevent a known failure of a 6th gear shaft bearing. Refer to the following thread for more information: