T56 additive?
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Joined: Jan 2019
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T56 additive?
Hey all. I changed the transmission fluid on my manual 2002 couple using the suggested AC Delco 88861800 fluid. Immediately after the fluid change, I felt like it shifted slightly rougher. I was surprised to say the least. Vette has 67k miles on it and I figured the fluid was maybe changed once before me. After 3k miles, I can say it definitely doesn’t shift as well as before. My issues are 1st gear is tough to get into sometimes and 2nd gear often feels like it moves past 3 notches before it’s in gear. Are there any additives people are using to smooth out their synchros? Also, i am beginning to worry that maybe there is a bit more fluid in there than recommended. I pulled the filler tube quick and installed the screw while it was still leaking quickly. Could this be part of the issue?
Melting Slicks
Joined: Jun 2013
Posts: 3,473
Likes: 691
From: West Virginia
Do you know what fluid was in there before the change? Without that info it's hard to say. It might have been a synthetic, for example. A number of them out there and users reckon they lighten up the shifting. You mention the possibility of being over full - that won't have that effect. If anything your symptoms are those to be expected when the fluid level is low, not high.
As an aside, I am running Valvoline DexMerc, a non synthetic "DEX III" fluid, which is what the AC Delco stuff is - and what the T56 was designed for. When I put that in, at about 70k, shifting improved noticeably, but I did note that rather less fluid came out than went in. And it was pretty nasty looking. So much for the claimed "lifetime fill".
As an aside, I am running Valvoline DexMerc, a non synthetic "DEX III" fluid, which is what the AC Delco stuff is - and what the T56 was designed for. When I put that in, at about 70k, shifting improved noticeably, but I did note that rather less fluid came out than went in. And it was pretty nasty looking. So much for the claimed "lifetime fill".
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Joined: Jan 2019
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Do you know what fluid was in there before the change? Without that info it's hard to say. It might have been a synthetic, for example. A number of them out there and users reckon they lighten up the shifting. You mention the possibility of being over full - that won't have that effect. If anything your symptoms are those to be expected when the fluid level is low, not high.
As an aside, I am running Valvoline DexMerc, a non synthetic "DEX III" fluid, which is what the AC Delco stuff is - and what the T56 was designed for. When I put that in, at about 70k, shifting improved noticeably, but I did note that rather less fluid came out than went in. And it was pretty nasty looking. So much for the claimed "lifetime fill".
As an aside, I am running Valvoline DexMerc, a non synthetic "DEX III" fluid, which is what the AC Delco stuff is - and what the T56 was designed for. When I put that in, at about 70k, shifting improved noticeably, but I did note that rather less fluid came out than went in. And it was pretty nasty looking. So much for the claimed "lifetime fill".
Yea, im not sure what was in there prior to the change. Previous owner would have done it. Since all of the fluids were a bit dark, I figured it would have been awhile since the change was done. Previous owner was an older man with a son working for Chevy, so I figure if he did do a change at some point, Chevy would have done the work.
Maybe the answer is just that the synchros are getting worn out.
Last edited by Tenshots1; Jun 20, 2019 at 02:09 PM.
Burning Brakes
Joined: Jul 2018
Posts: 1,113
Likes: 144
From: Miami
Hey all. I changed the transmission fluid on my manual 2002 couple using the suggested AC Delco 88861800 fluid. Immediately after the fluid change, I felt like it shifted slightly rougher. I was surprised to say the least. Vette has 67k miles on it and I figured the fluid was maybe changed once before me. After 3k miles, I can say it definitely doesn’t shift as well as before. My issues are 1st gear is tough to get into sometimes and 2nd gear often feels like it moves past 3 notches before it’s in gear. Are there any additives people are using to smooth out their synchros? Also, i am beginning to worry that maybe there is a bit more fluid in there than recommended. I pulled the filler tube quick and installed the screw while it was still leaking quickly. Could this be part of the issue?
PS: I don't think you did anything wrong with how you filled it up. You're supposed to fill until it starts to leak out, then quickly put the screw back. You're only going to lose maybe half of an ounce worst case during the process.
Last edited by turabo87; Jun 20, 2019 at 02:29 PM.
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Joined: Jan 2019
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That's odd. It's usually the other way around. I had your symptoms BEFORE I changed my trans fluid. Mine has 95k miles and looked like it still had original fluid inside (looked red but smelled burnt). I put RP Synchromax and shifts much better. No more "2 steps" to engage 2nd. Gives me more TONS more confidence shifting into 2nd.
PS: I don't think you did anything wrong with how you filled it up. You're supposed to fill until it starts to leak out, then quickly put the screw back. You're only going to lose maybe half of an ounce worst case during the process.
PS: I don't think you did anything wrong with how you filled it up. You're supposed to fill until it starts to leak out, then quickly put the screw back. You're only going to lose maybe half of an ounce worst case during the process.
Yea this is what I expected as a result of doing the change myself. I'm really just not sure.
Drifting
Joined: Jul 2015
Posts: 1,844
Likes: 376
From: San Jose, CA
Indeed. I use amsoil, not for any really scientific reason, but because they seem to make good lubes and my car can use 'em so why not.
Amsoil, redline, royal purple, mobil, etc, all of them make a perfectly good full synth trans fluid that people are happy with. Some people will say (eg) that redline was notchy but amsoil was butter; some will say (eg) that amsoil was notchy but redline was butter; some will say they found one of the several royal purple offerings to be best, and so on. I don't think any one of them is necessarily better or worse across the board, but I think it's clear that due to some variation internally, some fluids work better in some transmissions than others.
Amsoil, redline, royal purple, mobil, etc, all of them make a perfectly good full synth trans fluid that people are happy with. Some people will say (eg) that redline was notchy but amsoil was butter; some will say (eg) that amsoil was notchy but redline was butter; some will say they found one of the several royal purple offerings to be best, and so on. I don't think any one of them is necessarily better or worse across the board, but I think it's clear that due to some variation internally, some fluids work better in some transmissions than others.
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