Synchromesh?!?!?!?

[rchaskin]

I just got to putting the fluid in myLT1 style T-56 and noticed that the part number they gave me for Syncromesh at the GM counter was 1052931.

He said that the 12345349 number for synchromesh replaced the old number 1052931.

Does anyone have any insight on this, or did I get the shaft at the parts counter?

Randy

[Bigblue73]

I would question that part number since the 12345349 has been around for a while (at least six years). My 2 cents on this. GMJIM chime in on this.

[GMJim]

That number (1052931) was used in the ZF Transmission in the Corvette 1990 to 1996 and some other applications. It's a Texaco blend 5W-30. The 12345349 is made by Pennzoil for GM. It's basically a 5W-30 oil as well but I would question if it has the same properties, though it does meet the same GM specification GM 9985648. GM doesn't change part numbers unless something is different. I would use the later number in the ZF transmission but not the older number in the newer tranny (TKO). Bigblue73 is right. The 12345349 number has been around for a long time and anyone having the old 1052931 oil doesn't sell much oil. Tremec specifically recommends the 12345349 so if it were up to me I would return the 1052931 and buy what is recommended. You could also use the Pennzoil Synchromesh as its the same as the GM 12345349. It's cheaper and should be available at most aftermarket parts stores.
Jim

[rchaskin]

WOW, thanks for the info.

I will go and swap it out today.

[wmhjr]

Or use Amzoil synchromesh.

[GMJim]

Or use Amzoil synchromesh.

Amsoil is very good oil but isn't on the list of approved oil for Tremec. That doesn't mean it isn't good oil! Just that it wasn't tested and approved. Keep in mind that if you run a non approved oil in your new Tremec it will void the warranty. After the warranty period it doesn't really matter.

[wmhjr]

Amsoil is very good oil but isn't on the list of approved oil for Tremec. That doesn't mean it isn't good oil! Just that it wasn't tested and approved. Keep in mind that if you run a non approved oil in your new Tremec it will void the warranty. After the warranty period it doesn't really matter.

I'm not sure that's correct - though you might know better than I. Amsoil synthetic manual synchromesh transmission fluid is compliant with GM 9985648, 9986105, and 9985535. Part numbers 123453498, 12345577, 12377916, and 1052931

It explicitly lists the TREMEC TKO600 on the bottle.

[AintQik]

But he is running an LT1 T56 no? The guys that built mine told me to run Mobil Synthetic in it they have run their trannys behind 800 horse motors with no issues and this is without Viper gears, just better forks, sliders and stuff. Any opinions on that? I'd like this old LT1 T56 to last a bit.

Or if I should run the Syncromesh, which is the right number for the LT1 T56?

[wmhjr]

I'm not near the bottle right now, but directly from the AMSOIL site....

"
APPLICATIONS
Recommended for automotive and light-truck applications that require synchromesh transmission fluid. Applications include manual transmissions and transaxles such as New Venture NV T350, NV 1500, NV 2550, NV 3500, NV 3550, NV 5600, and Tremec T4, T5, T18, T56, T176, TKO500, TKO600, TR 3450 and TR 3550. Replaces MTF-94 fluid for Land Rover, MG, and Mini Cooper. Replaces Honda Genuine MTF fluid for manual transaxles and Texaco MTX fluid. Not for use in engines, hypoid rear axles, limited-slip or wet clutch applications.

[rchaskin]

I finally got four qts of Penzoil Synchromesh.
(It took going to about 8 stores over three towns!! HA!)

It seems too shift very good, all but 5th.
I think the syncros are bad.

On a side note, I think the stuff should be called "Synchro-mess".
I dont care which, or how you use a transfer pump, I always end up with fluid everywhere!!

[GMJim]

I'm not sure that's correct - though you might know better than I. Amsoil synthetic manual synchromesh transmission fluid is compliant with GM 9985648, 9986105, and 9985535. Part numbers 123453498, 12345577, 12377916, and 1052931

It explicitly lists the TREMEC TKO600 on the bottle.

That's correct. The oil manufacturer says it meets the spec and will work for a Tremec but Tremec has not put it on the list of approved oil for their transmissions. Wrong oil, no warranty.

BTW you CAN run the Synchromesh in the earlier T56 but they used ATF in those from the factory. The Synchromesh will be fine and will actually run quieter.
Jim

[wmhjr]

That's correct. The oil manufacturer says it meets the spec and will work for a Tremec but Tremec has not put it on the list of approved oil for their transmissions. Wrong oil, no warranty.

BTW you CAN run the Synchromesh in the earlier T56 but they used ATF in those from the factory. The Synchromesh will be fine and will actually run quieter.
Jim

Let me preface this by saying you're the expert in this area and I'm not - however TREMEC very clearly publishes a SPEC of what should be used, and the Amsoil synchromesh is compliant with and meets that SPEC. Specifically, it calls for either GM synchromesh part # 12345349 or Dextron III/Mercon Spec ATF fluid. I am highly confident that TREMEC would be completely unsuccessful in a position that a warranty would not be covered resulting from using a brand they don't explicitly list. There are federal laws in the US specifically around this particular issue, and thus far there is extremely strong precedence of manufacturers being completely unsuccessful in making such a claim. They would have to prove that the Amsoil composition failed to meet the published spec AND they would have to publish in advance that the use of Amsoil would void the warranty. I seriously doubt that TREMEC would even try, but if they did with me, bring it on....

[GMJim]

I am not a lawyer but merely the messenger and have had this conversation with Tremec many times. There is no expertise required here. Use the unapproved oil and no warranty. The spec you are reading is a GM spec. GM that says the GM Synchromesh meets GM spec XYZ not Tremec's spec. Amsoil and other companies make oil that meet the GM spec XYZ as well so I would guess that if you have a Tremec transmission in your GM car that GM is warranting it, not Tremec. Use what you like and take your chances!

[wmhjr]

Jim, I think you missed a VERY important part of the documentation.

"either GM synchromesh part # 12345349 or Dextron III/Mercon Spec ATF fluid"

I'm pretty sure you have that document since you guys sent it to me with the TREMEC The "Or" in that statement is pretty broad. Nowhere in the documentation does it require ONLY that GM Synchromesh be used.

Beyond that, there is zero possibility that TREMEC can avoid warranty claims if the lube meets the published spec. There are a few engine manufacturers that have tried this over the years, and they have been consistently trounced. I'm not sure what TREMEC has told you, and I'm not telling anyone else what to do. But....

Harley tried it with motor oil - they got summarily slammed and no longer attempt to do so.

Honda (cars, not bikes) tried, same result.

US courts have been extremely consistent in consumer protection here. Manufacturers are free to require a specification. They are not permitted to require a "brand". It is illegal. Any brand can provide a blend that meets that spec. In order to deny the claim, TREMEC would have to prove Amsoil failed to meet the specification. They may well try to push a customer around, but any knowledgable customer will rip their short hairs out.

Bottom line - TREMEC cannot legally refuse a warranty claim if the customer uses ANY manufacturers oil that meets the spec published by TREMEC for THAT PARTICULAR TRANNY. In this case, the TKO600 (that I bought from you - welcome) clearly documents the spec that the Amsoil lube meets. TREMEC is responsible for any warranty claim. I'm glad TREMEC is building these trannies, but under no cirumstances should they be allowed to avoid their responsibilities.

[GMJim]

No I didn't miss it and I don't disagree with your rationality. We could kick this around all day and not make any sense of it. Give them a call and see if you get somebody there to explain it to you. I've tried. 1-800-401-9866.

Keep one thing in mind. It's not entirely about the lubrication, but the coefficient of friction for the synchros. These things would probably run on lard for lube but they won't shift very well.

[wmhjr]

No I didn't miss it and I don't disagree with your rationality. We could kick this around all day and not make any sense of it. Give them a call and see if you get somebody there to explain it to you. I've tried. 1-800-401-9866.

Keep one thing in mind. It's not entirely about the lubrication, but the coefficient of friction for the synchros. These things would probably run on lard for lube but they won't shift very well.

Jim, I completely agree with the above. I just may call TREMEC (talked to them recently in person but never thought to discuss this - my tranny is out of warranty anyway).

The spec is all about the blend - not just lubrication. It's all about the different additivies. There are all kinds of requirements to meet a specific blend spec. The lube oil is the least complex part of it. We also own some heavy iron (dozer, etc) so I'm pretty familiar with the whole oil spec thing. There aren't many companies that are more particular with oil requirements than folks like CAT and their brothers. Also have a friend who retired from Shell who was involved in this, so got a great education about how oil blends are developed and tested including fleet involvement. Interesting stuff.

Anyway, listen to me ramble. Like I said, I'm sure you're way more familiar with some of this stuff than me.

[GMJim]

Talking about lube, this is not related at all to our conversation above but the shop I help out at from time to time recently did an automatic tranny on a 2006 BMW and the transmission needed 12 quarts for a complete overhaul. The only fluid recommended for this tranny is only available at BMW at $108.00 per quart!!!!! Try to convince that guy that he has to use BMW fluid! Wrong fluid no warranty. The rebuild was $3700.00!! Fluid $1300.00 Total $5000.00!

[wmhjr]

Was it an automatic or an SMG? Never heard of a bmw auto needing that. Makes me curious.... I know they were REAL particular about the SMGs. Course, now that I think of it an SMG is not likely, as I can't think of many "local" shops (other than folks like DINAN) who could take that on.

[woody80z28]

I've been using Dexron III in my LT1-T56 for years and GM Syncromesh in my HM-282, but I didnt realize you could run Syncromesh in a T56. Would Syncromesh help at all with a slight grind I have now & then when shifting to reverse?

[GMJim]

This was an automatic in a 800 series car. I believe it was a six speed.

Woody
The synchromesh won't help the grind. You can try some of the friction modifiers out there designed for manual transmissions but in the end it will need synchros.