Everyone keeps asking about GM's fluid - it is classified as a GLS, or "Gear Lube - Special" by API standards. Those are lubricants spec'd by the manufacturer for certain transmissions, almost always to ensure they are not damaged by using lubricants with formulas that can do harm - an example would be using a GL-5 with actuve sulphur compounds as EP agents gear lube in a tranny with "yellow" metals: bronze, copper, etc. The chemical reaction between the two can be disastrous.
GM had troubles with some of the Getrag trannies it sources from Germany, and the warranty claims get expensive.
Here is Quaker State's product description for its product which meets the same spec as GM's Synchromesh:
PRODUCT DESCRIPTION QUAKER STATE®SYNCHROMESH FLUID is a synchromesh transmission fluid designed for certain manual transaxles and manual transmissions used by General Motors or Chrysler. QUAKER STATE®SYNCHROMESH FLUID is formulated with high quality paraffinic base stocks, a fluidity modifier, multifunctional performance additives, corrosion inhibitors, a foam suppressor and a shear stable viscosity index improver additive. It provides excellent oxidation stability, low temperature performance, excellent synchronizer performance and compatibility with yellow metals, such as bronze, brass and copper components found in manual transaxles and transmissions. This product will satisfactorily lubricate General Motors or Chrysler manual transaxles and transmissions from -40°C to +150°C. APPLICATION QUAKER STATE®SYNCHROMESH FLUID is specifically formulated for synchromesh transmissions used by General Motors requiring General Motors Part No. 12345349 (Specification No. 9985648) Synchromesh Transmission Fluid or Chrysler transmissions requiring Part No. 4874464 (Specification MS-9224). It is also recommended for use in General Motor transmissions requiring General Motors Part No. 12345577. It is listed in the Pennzoil Lubrication Recommendation And Capacities Guideas "GLS." QUAKER STATE®SYNCHROMESH FLUID is NOT intended for all GLS applications. You must verify the manufacturer's part number, indicated by a superscript number and found at the end of the vehicle application listing. BENEFITS Exhibits excellent low temperature performance Meets GM Specification 9985648 Suitable for use in GM manual transaxles and transmissions requiring GM part number 12345349 or 12345577. Meets Chrysler specification MS-9224 Suitable for use in Chrylser transaxles and transmissions requiring part no. 4874464 Excellent synchronizer performance Excellent yellow metal compatibility TYPICAL PHYSICAL AND CHEMICAL PROPERTIES TEST METHOD TYPICAL RESULTS API Gravity ASTM D-1298 27.3 Flash Point, COC, °F ASTM D-92 385 Pour Point, °F ASTM D-97 -50 Viscosity ASTM D-445 @ 40°C, cSt 41.6 @ 100°C, cSt 9.08 @ 100°F, SUS 209.4 @ 210°F, SUS 56.7 Viscosity Index ASTM D-2270 208 Material Number 12/1 Quart 56173 March, 2000 Stock # 59634
Analysis: Note this is a mineral , paraffinic base stock. It has additives and VI improvers, so it is essentially a kind of motor oil adapted for tranny use - no big deal, Honda used motor oils successfully in its trannies for years.
However, it does not have the advanced stock of the best ATF's, including the Dexron III/Mercon V, which are essentially Group 3 synlubes. Nor does it have the benefits of a Group IV lubricant such as a PAO (Amsoil ATF), di-basic ester (Neo), or Group V polyol ester (Red Line).
So it is subject to the same problems of ordinary mineral oils - they lube well for the mainstream, but at the extremes (cold, very hot, and under severe operating conditions such as towing, drag or track use), they are susceptible to the same shear instability, viscosity changes, as regular engine oil.
So it is my opinion that while it is a perfectly good lube, and will not harm any transmission for which it is spec'd, it is not a miracle product, and I believe (and use myself) lubricants I think offer a extra measure of performance and security:
Examples:
Red Line D4 ATF; Red Line MTL
Valvoline Durablend ATF
Amsoil ATF
Mobil 1 ATF
GM had troubles with some of the Getrag trannies it sources from Germany, and the warranty claims get expensive.
Here is Quaker State's product description for its product which meets the same spec as GM's Synchromesh:
PRODUCT DESCRIPTION QUAKER STATE®SYNCHROMESH FLUID is a synchromesh transmission fluid designed for certain manual transaxles and manual transmissions used by General Motors or Chrysler. QUAKER STATE®SYNCHROMESH FLUID is formulated with high quality paraffinic base stocks, a fluidity modifier, multifunctional performance additives, corrosion inhibitors, a foam suppressor and a shear stable viscosity index improver additive. It provides excellent oxidation stability, low temperature performance, excellent synchronizer performance and compatibility with yellow metals, such as bronze, brass and copper components found in manual transaxles and transmissions. This product will satisfactorily lubricate General Motors or Chrysler manual transaxles and transmissions from -40°C to +150°C. APPLICATION QUAKER STATE®SYNCHROMESH FLUID is specifically formulated for synchromesh transmissions used by General Motors requiring General Motors Part No. 12345349 (Specification No. 9985648) Synchromesh Transmission Fluid or Chrysler transmissions requiring Part No. 4874464 (Specification MS-9224). It is also recommended for use in General Motor transmissions requiring General Motors Part No. 12345577. It is listed in the Pennzoil Lubrication Recommendation And Capacities Guideas "GLS." QUAKER STATE®SYNCHROMESH FLUID is NOT intended for all GLS applications. You must verify the manufacturer's part number, indicated by a superscript number and found at the end of the vehicle application listing. BENEFITS Exhibits excellent low temperature performance Meets GM Specification 9985648 Suitable for use in GM manual transaxles and transmissions requiring GM part number 12345349 or 12345577. Meets Chrysler specification MS-9224 Suitable for use in Chrylser transaxles and transmissions requiring part no. 4874464 Excellent synchronizer performance Excellent yellow metal compatibility TYPICAL PHYSICAL AND CHEMICAL PROPERTIES TEST METHOD TYPICAL RESULTS API Gravity ASTM D-1298 27.3 Flash Point, COC, °F ASTM D-92 385 Pour Point, °F ASTM D-97 -50 Viscosity ASTM D-445 @ 40°C, cSt 41.6 @ 100°C, cSt 9.08 @ 100°F, SUS 209.4 @ 210°F, SUS 56.7 Viscosity Index ASTM D-2270 208 Material Number 12/1 Quart 56173 March, 2000 Stock # 59634
Analysis: Note this is a mineral , paraffinic base stock. It has additives and VI improvers, so it is essentially a kind of motor oil adapted for tranny use - no big deal, Honda used motor oils successfully in its trannies for years.
However, it does not have the advanced stock of the best ATF's, including the Dexron III/Mercon V, which are essentially Group 3 synlubes. Nor does it have the benefits of a Group IV lubricant such as a PAO (Amsoil ATF), di-basic ester (Neo), or Group V polyol ester (Red Line).
So it is subject to the same problems of ordinary mineral oils - they lube well for the mainstream, but at the extremes (cold, very hot, and under severe operating conditions such as towing, drag or track use), they are susceptible to the same shear instability, viscosity changes, as regular engine oil.
So it is my opinion that while it is a perfectly good lube, and will not harm any transmission for which it is spec'd, it is not a miracle product, and I believe (and use myself) lubricants I think offer a extra measure of performance and security:
Examples:
Red Line D4 ATF; Red Line MTL
Valvoline Durablend ATF
Amsoil ATF
Mobil 1 ATF
