[cwebster]

This post is to describe how & why I changed the manual transmission fluid in my 2017 Camaro ZL1 M6 to Royal Purple Synchromax. I did this at 2000 miles, about a week after my last engine/diff oil change.

Why?

1. The "clunky" shifts. One of the few gripes I had with the 6th Gen ZL1 was that shifting between gears was not as smooth as I had expected. I felt like it was having a negative effect on my 1/4 mile ET's. The 4-speed Muncie on my '70 Nova SS 396 had buttery smooth synchros back in 1975 and nothing I've driven since has measured up. In fact, it felt a lot like my 5th Gen SS 1LE. Come to find out it is the same tranny.

2. Good reviews for RP Synchromax. Most Camaro/Corvette owners who use RP Synchromax experience noticeable improvement. Forum searches turned up several positive reviews on replacing stock oil with RP Synchromax. $18.25 on Amazon

3. Just to be on the safe side. After changing the engine oil and differential gear oil 3 times, I felt like I should change the tranny fluid too. Even though there's no mention of accelerating the change interval for competitive driving events, I reasoned that the transmission must be experiencing some of the same torque and stresses as other drive train components. Can't hurt to err on the safe side...

How?

You'll need 4 qts oil, a suction gun or siphon pump, rags, 3/8" ratchet, 3/8" drive 1" extention, and 3/8" drive swivel. The suction gun is so much faster and easier. See bottom for the one I use.



1. Put the car up on a lift (you can do this on jack stands too).

2. Loosen and remove fill plug. It's located about mid-way on the left side near the top. See the red thread-lock coating in the photo? It uses plugs similar to the differential. You'll need a 3/8" drive ratchet and a short (1-3") extension.



3. Loosen drain plug. This is on the right side near the rear of the transmission, just above the mount cross-member. See the same red thread-lock compound? You'll need a 3/8" drive ratchet and swivel for this one.



4. Position a large drain pan just below and centered on the transmission mount cross-member.

5. Remove the plug and stand back. This will be messy - no way around it without jacking the tranny and removing the cross-member. Position a Mason jar under the main flow if you want to catch a sample.

6. Reposition drain pan as necessary



7. Examine magnetic drain plug for metal filings/chips. Check the sample for suspended or settled debris.
- A small amount of fine particles is normal.
- First fluid change may have more fine particles but no flakes or chunks.
- Color should be clear, bright red, not much darker than new fluid.

8. Allow to fully drain until there's a slow drip. Thoroughly clean the plug - especially the threads.

9. Wipe out the drain hole with a lint-free cloth. Then place thread-lock compound on the first half of threads of the drain plug. Finally, replace and tighten.
- Not sure of torque. I try to match what I felt coming off - 15-25 ft lbs should do it.

10. Fill a suction gun with new oil and position the tube inside the fill hole.

11. Refill until fluid starts coming back out.
- You'll have to fill the gun several times. Capacity is 3.5L (3.65 qts) so should take under 4 qts if your gun doesn't leak.
[Edit 20170813]
- Transmission is full when oil level is 1/8" below fill plug hole. (Thanks to vtirocz in Post #49)
- Use a bent piece of coat hanger or bailing wire marked 1/8" from bend as a makeshift dip-stick.
- May need to suck some fluid out after filling or slowly add 'til fluid level is correct.

12. Wipe out the fill hole with a lint-free cloth. Then place thread-lock compound on the first half of threads of the fill plug. Finally, replace and tighten - same as drain plug.

13. Thoroughly clean and wipe-down the transmission and mount. There's going to be oil in hard-to-reach places. I stuffed a rag underneath and pulled it through the tight spots several times.

Suction Gun:

I bought one of these. It works great and doesn't leak. I use it mostly for differential gear oil but it works great for transmission fluid changes too. I like it because it's body is clear so I can see how much fluid is in there. wipe it clean inside and out with a lint-free cloth after each use.

Plews 30-740 UltraView Suction Gun with Red Tube Ends $24.62

--Cal

[Tara Martin]

Nice work! Thanks for the tips!

[cwebster]

Originally Posted by Tara Martin

Nice work! Thanks for the tips!

You bet!

With my Swiss cheese brain, I'll probably come back to review it on a future oil change myself.

[gilgamesh]

Great write up, man. Thank you. I want to do this same deal myself.

[somewhatdamaged]

Great post and instructions. One thing I would highly recommend is to take that extra step and remove the brace/use a tranny jack - for me the amount of mess/amount of fluid coming out of there it was much cleaner just to remove the brace.

[Burnt Rubber]

Thanks for all this great info. Are you running with the stock shifter and if not do you think if MGW had one out yet it would help?

[Infern0]

subscribed

[cwebster]

Originally Posted by Burnt Rubber

Thanks for all this great info. Are you running with the stock shifter and if not do you think if MGW had one out yet it would help?

If it were just a matter of ergonomics I'd say yes but I think the "clunki-ness" is simply from the inferior synchronizers in this transmission. They simply don't match up the gears well enough.

--Cal

[cwebster]

Originally Posted by somewhatdamaged

Great post and instructions. One thing I would highly recommend is to take that extra step and remove the brace/use a tranny jack - for me the amount of mess/amount of fluid coming out of there it was much cleaner just to remove the brace.

You're right. It would be much cleaner. By all means, take these extra steps if you feel so inclined. For me it was quicker to drain, refill, and wipe up. It gives me a little more time to go over all the drive and suspension components while I have it on the lift. The under-body parts tend to dry out and oxydize anyway so I use the oily (not drenched) rags to wipe down those dry parts.

[TJay74]

One of the first "mods" I did on my 1LE. I went ahead and removed the cross member, made it a lot easier and no mess.

[Evolvedx27]

Nice write up. Zl1 "how to" section a possibility?

[Shorty45]

Thanks Cal for the in depth write up. I agree with you on the Muncie. My M-21 I rebuilt for my Chevelle is still really smooth 7yrs later. Looking fwd to trying the RP fluids out.

[cwebster]

Originally Posted by Evolvedx27

Nice write up. Zl1 "how to" section a possibility?

I suppose I should have put this in the Mechanical Maintenance: Break-in / Oil & Fluids / Servicing discussion group, although it wouldn't get the exposure for the ZL1 owners that it gets here. In a week or so I can ask one of the admins to move it.

Originally Posted by Shorty45

Thanks Cal for the in depth write up. I agree with you on the Muncie. My M-21 I rebuilt for my Chevelle is still really smooth 7yrs later. Looking fwd to trying the RP fluids out.

Awesome! I'd love to see that Chevelle in action. There's nothing quite like the deep, throaty roar of an old-school big-block engine climbing through the gears. Most of the time, I only used the clutch for 1st gear in my old Nova. A top-of-the-line muscle car like the ZL1 should have better synchros IMO.

[Bow Tie Affair]

Originally Posted by TJay74

One of the first "mods" I did on my 1LE. I went ahead and removed the cross member, made it a lot easier and no mess.

Does anybody have torque values for the cross member and transmission mount?