Originally Posted By: badtlc
I think you took that completely the wrong way. I'm saying your post was written like you were talking only about the fluids you listed. That is fine. It is a great and helpful list but I'm not talking about specific fluids.
I am curious about synchromesh fluids in general, not the fluids you are familiar with. I don't get why they call them synchromesh in the first place and not MTLs or MTFs. Does the term synchromesh imply something that requires GL-4 protection? Is this why they don't take time to list GL applications? I just don't get why these companies are not putting this information out there if the fluids provide such protection.
I hope you don't think I'm picking you Molakule. I think you took the previous post as a personal shot and it was not.
OK, but you sounded somewhat accusative. Maybe I mistook your comments.
All of the fluids I listed in the link are GL-4 fluids suitable for synchromesh Manual Transmissions.
This discussion is about light truck and passenger car Manual Transmission fluids specifically.
1. most Manual Transmissions (except some HD trucks of course) have synchronizer assemblies of brass or carbon fiber construction
2. most manual transmissions have a gearset with a particular type of construction
Quote:
Gearing: Most gear types in manual transmissions are of the helical type, which because of the cut, reduce noise and vibration. Due to their angular cut, thrust loads are transmitted to the shafts on which they reside. The gears on the input and output shafts are usually produced in one integrated piece, called “gear clusters, “ or the cluster gear assembly. You will notice the only gear that is actually moved is the reverse idler gear. This is moved into position to mesh with the small reverse gear on the input shaft so you can “back up” or reverse direction. At higher reverse speeds, this gear will usually give off the familiar “reverse” whine. Lubricant effects: Being in constant mesh, they are dipping in the oil bath and slinging the oil up to the shifter assembly. Since they transmit torque, they must have an anti-wear additive in the lubricant in order to reduce wear. The slipping and rolling action of the gear teeth causes localized high pressures and heating. The anti-wear additive forms a protective but complex ferrous film at the contact surface to protect from galling and other wear mechanisms. Other components such as thrust washers, flat thrust bearings of the roller type, and shims may also need cooling, lubricant film, and anti-wear additives as well.
3. In order to protect the gears, bearings, shafts and shims, a GL-4 AW protection additive is part of the fluid package, hence they carry a GL-4 protection rating.
4. in order to allow smooth synchronizer engagement, a special friction modifier is included.
Since the discussion is about light truck and passenger car transmissions, and not HD OTR transmissions, the fluids in these light truck and passenger car transmissions have to have a Manual Transmission "synchromesh" fluid.
If this doesn't answer your question, may be you can be more specific and we can go from there.
Manual (synchromesh) Transmission Technology