Manual trans and synchronizer questions

[dakota1820]

After my diff pin thread I got to thinking. What is the reason to use atf style fluid in our manuals?
I understand we have fiber synchronizers? I am not positive of the exact material. My 14 Dodge dart has the c635 6 speed Manual and it has fiber synchronizers as well. I am running redline mt-85 in it. It is thicker than the factory fluid but I have had zero issues even in the cold weather. It feels great! And has for a couple years.
I made this choice because this same transmission is used in Europe in many of Fiats and Alfa Romeos and the fluid they use over there is quite a bit thicker that what is specd here.
So I guess my question is what fluids will harm our synchronizers what else beside atf is a safe bet? I know the transynd is recommended as is the amsoil but they are not easy to get around here and I'd like something widely available

[OldNuc]

ATF or Synchromesh fluids only

[fdryer]

I've never read or heard of manual xmission synchronizers made of fiber. Conventional manuals are all metal. Brass synchronizers. Exotic carbon fiber? Maybe new for specific vehicles. My guess is the S-series doesn't use carbon fiber anywhere. Since its adapted from rocket science, trickling down to applications as forming and layout costs dropped, carbon fiber costs are low enough to use in applications where its properties can replace weaker parts for better durability. Reading your post prompted me to goggle it with this result; https://www.sae.org/publications/tec.../1999-01-1059/. Unless specified in racing applications, I don't see any advantages to daily drivers where most manuals of low cost cars would justify expensive carbon fiber. On high end cars like Ferraris, yes but then again manual xmissions are disappearing in favor of dual clutch paddle shifting without a clutch pedal....... GMs Corvettes are still manual three pedals for those insisting on them otherwise the 6, 7, 8 speed autos make ordinary drivers unable to coordinate pedal shifting into wannabe track tracers. Even Formula-1 racers, if I'm not mistaken, only have to clutch in first gear then the rest of the race at any speed uses paddle shifters and dual clutches for the fastest manual shifts possible yet allow drivers to shift at any speed and rpm to remain in the torque band for the most power to the wheels.

[dakota1820]

Originally Posted by fdryer

I've never read or heard of manual xmission synchronizers made of fiber. Conventional manuals are all metal. Brass synchronizers. Exotic carbon fiber? Maybe new for specific vehicles. My guess is the S-series doesn't use carbon fiber anywhere. Since its adapted from rocket science, trickling down to applications as forming and layout costs dropped, carbon fiber costs are low enough to use in applications where its properties can replace weaker parts for better durability. Reading your post prompted me to goggle it with this result; https://www.sae.org/publications/tec.../1999-01-1059/. Unless specified in racing applications, I don't see any advantages to daily drivers where most manuals of low cost cars would justify expensive carbon fiber. On high end cars like Ferraris, yes but then again manual xmissions are disappearing in favor of dual clutch paddle shifting without a clutch pedal....... GMs Corvettes are still manual three pedals for those insisting on them otherwise the 6, 7, 8 speed autos make ordinary drivers unable to coordinate pedal shifting into wannabe track tracers. Even Formula-1 racers, if I'm not mistaken, only have to clutch in first gear then the rest of the race at any speed uses paddle shifters and dual clutches for the fastest manual shifts possible yet allow drivers to shift at any speed and rpm to remain in the torque band for the most power to the wheels.

A lot of transmissions use non brass synchros, they are a clutch like material.......example right off the top of my head would be the nv4500 trans.

[dakota1820]

Originally Posted by OldNuc

ATF or Synchromesh fluids only

Synchromesh won't hurt the synchronizers or anything? Wasn't sure if it would be compatible or not.

[OldNuc]

Amsoil Synchromesh works, others unknown.

[dakota1820]

Yea the only synchromesh widely available here is Pennzoil. Wonder if I could try to pull up a data sheet on them both and see how similar they are, if at all.

[OldNuc]

It is the actual chemicals in the additive package that you are concerned with and that is usually proprietary info.

[dakota1820]

I planned on looking up a voa.
Doesn't seem to be many Dex 3 options anymore so it would be nice to find something available that's decent quality.

[Waiex191]

Originally Posted by dakota1820

Doesn't seem to be many Dex 3 options anymore so it would be nice to find something available that's decent quality.

There is always this:
https://www.amazon.com/Castrol-03520.../dp/B00DILUBL6

Works fine in both my 5 speed saturns and also my $200 Buick.

[dakota1820]

Originally Posted by Waiex191

There is always this:
https://www.amazon.com/Castrol-03520.../dp/B00DILUBL6

Works fine in both my 5 speed saturns and also my $200 Buick.

I wonder what the actual viscosity is. I'd like something a little thicker to cushion the gears especially the differential more than than the atf.

[fdryer]

I think your concern to use a higher viscosity xmission oil may be overly concerned. Presuming brass synchronizers are used, the main concern from GMs view is reasonably long term life with either normal non commercial use of Saturns, a relatively low viscosity xmission oil to provide long term lubrication with minimal wear of gears and bearings, and lower parasitic loads - contributing to higher fuel economy. I remember during the Neanderthal Age when 90 weight gear oil was used in manual xmissions. In freezing temps, the oil was too thick and the shifts were very stiff until a few blocks of driving warmed up oil when shifts were normal. Using heavy weight oil and having a temporary hard shift for a mile or so was the price of 90w gear oil. With vehicles having emissions systems and increasing fuel economy, thinner oil viscosity without degrading performance meant auto manufacturers decided to use thinner oil with better chemistry to afford the same long term reliability and reduce the tendency to having initial stiff shifts in freezing weather. Missouri is a cold weather state. You might consider thicker weight oil having this tendency in freezing conditions, at least during the first few minutes of driving. Whether thicker weight oil is beneficial may or may not be advantageous when improved gear oil allows lower viscosity without a reduction in long term wear. If possible, search for xmission repair sites that can help you with more information.

[OldNuc]

The blocking ring is steel with glued on friction material. Some, most, gear oils will dissolve the glue. The actual synchronizer is just hardened steel like the blocking ring.

[Waiex191]

It's not broken. Don't fix it! In my opinion anyway.

[bumpdraft]

Originally Posted by OldNuc

ATF or Synchromesh fluids only

Kinematic Viscosity at 100 deg. C / at 40 deg. C
Torque-Drive. 7.6 / 37.1
Synchromesh 10.1 / 49.4

[OldNuc]

He wants a higher viscosity and that is how you do it.

[dakota1820]

Everything I have read here and over on Bob's the oil guy states that synchromesh should be fine. I am going to try Valvoline synchromesh because it is thinner than Pennzoil but thicker than atf

[OldNuc]

BITOG is no longer the quality reference it was when Bob was alive and running the site.

[dakota1820]

I am on their pretty often and though that may be true there are definitely a handful of intelligent folks . I talked to a guy who goes by mola kule quite a bit on this subject and he has made a ton of articles and posts regarding this topic and similar topic's.
Also it stands to reason that a gl4 oil won't hurt fiber / composite synchros. My dart and my vw have the same thing one calls for synchromesh and in one I run redline mt85 in. Both perform flawlessly.

[OldNuc]

It is not the fiber, it is the glue.