Hello there this is to kill any beleafs that using gl5 where gl4 is specified will kill a gearbox with 'yellow metal' internal parts I.e brass/copper synchros.
I found this over on another forum a while ago and here's the best bit. I own a 1.2 16v Renault Clio standered 5 speed box. I have used millers trx semi synthetic 75w90 gl5 transmission oil for the past almost 90,000 miles without any problems what so ever. That mileage has taken almost 10 years to accumulate read on and you will see exactly why there is nothing to worry about.
You're getting caught up in a very old wive's tale. GL-5 is OK for VW manual transmissions. In fact, you'll probably find 90% of the VW dealers use it. The subject came up again very recently so I went back to my source, one of the top lubrication chemical engineers for a major international supplier of both GL-4 & GL-5 as well as everything else including synthetics. National expert class. (His info also checks with their published materials manual.) This is the guy that investigated and supervised the lab tests of incidents that were claimed to be lube failures or damage. He says none were due to the GL-5 characteristics over GL-4.
First of all, if you are dropping out of gear, it has nothing to do with the syncros. It's worn gears, linkage adjustment or internal freeplay devloping.
There is nothing in GL-5 (or GL-4 for that matter that is corrosive.) In fact, both have the same anti-corrosive additives. (Try a litmus comparison test!) Also, there are NO brass synchronizers. Stop & think, real brass would wear out in a few weeks and is so soft it would dent or distort with the first few hard shifts. What you are seeing is an alloy that gives a gold-ish appearance. Probably a sintered iron &/or cadmium alloy to give it the friction characteristics desired. [A little side PS -- Porsche designed about 90% of the world's synchronizers and OKs GL-5.]
The difference between GL-4 & GL-5 is ONLY that GL-5 has an impact resistant additive. It was put in to prevent galling and to cushion the gear slap and impact every tranny has to a certain degree or another with acceleration & deceleration due to gear tooth clearance. The same characteristic of differentials. (By-the-way, VW differentials ARE VW transmissions, share the same oil, and have the same material spec gears.) I went out and re-read my stocks (Penzoil, Shell & MoPar OEM) just to be sure, and thay all say "Gear Oil", not differential oil -- in fact, GL stands for Gear Lubricant. (Hypoid is a style of gear cut found in both.) The MoPar is GL-4 yet all three are MIL2105D. The MoPar warns against using in other transmissions than their MoPar NV2500.
GL-4 meets MINIMUM specs and is why it's recommended. Just like DoT 3 may meet minimum specs for brake fluid, or SAE-SE (>'74 VW's) may meet minimum specs for engine oil. Engines & transmission evolve to put additional new strains on the lube, which call for additional new tehcnology lubricants. But with a few rare exception, the new lubes are backwards compatible. If GL-5 harmed trannies, you would have seen so many recalls, warnings and class-action law suits, your head would spin. Every factory manual and tech bulletin would be full of warnings. You don't say what year your Westy is, but I would hazard the guess that it's Type II or Vanagon, and GL-5 was just coming into general availability back then. Most manuals and specs were written for what was available then. Now, you'll be hard pressed to find it except in the discount or specialty lines.
I'm sure many distributors and sales departments want to justify why they continue to sell the GL-3's & 4's. And it's not that they are wrong -- I don't use the $10 super synthetic engine oils -- not because they are bad for my engine, but because they aren't worth the money -- diminishing returns for MY circumstances, but maybe not yours.
I'd hazard the guess that your tranny failure was totally unrelated. 800 miles is unlikely to create the wear or corrossion you claim. If it were common, how would most of us get hundreds of thousands out of a tranny. My '79 has had nothing but GL-5 and at 150K still hasn't got a clash. Mom's old Bug is at 158K without every being opened up. Their Vanagon is at 145K -- all original tranny. My current '90 4x4 Westy is 130K on the original synchros, as is my 31 year old Porsche. Definately not something that happens in 800 miles.
It's good to raise the question, but this one defies logic. Most of the incompatibilities are due to different techonologies (example - coolants) or different base product (example - DoT 4 & DoT 5 brake fluids), not due to the stepped-up supercession of technical specs within a line. Transmissions die from heat, contamination, lack of maintenance, and driving habits. They get moisture in them (through their breathers). An out-of-adjustment clutch will eat up synchros! Just routine gear wear ads to synchro strain. And everyone of us misses shifts and grinds the gears on occassion. Nothing is forever; synchros are actually a wear service item.
I found this over on another forum a while ago and here's the best bit. I own a 1.2 16v Renault Clio standered 5 speed box. I have used millers trx semi synthetic 75w90 gl5 transmission oil for the past almost 90,000 miles without any problems what so ever. That mileage has taken almost 10 years to accumulate read on and you will see exactly why there is nothing to worry about.
You're getting caught up in a very old wive's tale. GL-5 is OK for VW manual transmissions. In fact, you'll probably find 90% of the VW dealers use it. The subject came up again very recently so I went back to my source, one of the top lubrication chemical engineers for a major international supplier of both GL-4 & GL-5 as well as everything else including synthetics. National expert class. (His info also checks with their published materials manual.) This is the guy that investigated and supervised the lab tests of incidents that were claimed to be lube failures or damage. He says none were due to the GL-5 characteristics over GL-4.
First of all, if you are dropping out of gear, it has nothing to do with the syncros. It's worn gears, linkage adjustment or internal freeplay devloping.
There is nothing in GL-5 (or GL-4 for that matter that is corrosive.) In fact, both have the same anti-corrosive additives. (Try a litmus comparison test!) Also, there are NO brass synchronizers. Stop & think, real brass would wear out in a few weeks and is so soft it would dent or distort with the first few hard shifts. What you are seeing is an alloy that gives a gold-ish appearance. Probably a sintered iron &/or cadmium alloy to give it the friction characteristics desired. [A little side PS -- Porsche designed about 90% of the world's synchronizers and OKs GL-5.]
The difference between GL-4 & GL-5 is ONLY that GL-5 has an impact resistant additive. It was put in to prevent galling and to cushion the gear slap and impact every tranny has to a certain degree or another with acceleration & deceleration due to gear tooth clearance. The same characteristic of differentials. (By-the-way, VW differentials ARE VW transmissions, share the same oil, and have the same material spec gears.) I went out and re-read my stocks (Penzoil, Shell & MoPar OEM) just to be sure, and thay all say "Gear Oil", not differential oil -- in fact, GL stands for Gear Lubricant. (Hypoid is a style of gear cut found in both.) The MoPar is GL-4 yet all three are MIL2105D. The MoPar warns against using in other transmissions than their MoPar NV2500.
GL-4 meets MINIMUM specs and is why it's recommended. Just like DoT 3 may meet minimum specs for brake fluid, or SAE-SE (>'74 VW's) may meet minimum specs for engine oil. Engines & transmission evolve to put additional new strains on the lube, which call for additional new tehcnology lubricants. But with a few rare exception, the new lubes are backwards compatible. If GL-5 harmed trannies, you would have seen so many recalls, warnings and class-action law suits, your head would spin. Every factory manual and tech bulletin would be full of warnings. You don't say what year your Westy is, but I would hazard the guess that it's Type II or Vanagon, and GL-5 was just coming into general availability back then. Most manuals and specs were written for what was available then. Now, you'll be hard pressed to find it except in the discount or specialty lines.
I'm sure many distributors and sales departments want to justify why they continue to sell the GL-3's & 4's. And it's not that they are wrong -- I don't use the $10 super synthetic engine oils -- not because they are bad for my engine, but because they aren't worth the money -- diminishing returns for MY circumstances, but maybe not yours.
I'd hazard the guess that your tranny failure was totally unrelated. 800 miles is unlikely to create the wear or corrossion you claim. If it were common, how would most of us get hundreds of thousands out of a tranny. My '79 has had nothing but GL-5 and at 150K still hasn't got a clash. Mom's old Bug is at 158K without every being opened up. Their Vanagon is at 145K -- all original tranny. My current '90 4x4 Westy is 130K on the original synchros, as is my 31 year old Porsche. Definately not something that happens in 800 miles.
It's good to raise the question, but this one defies logic. Most of the incompatibilities are due to different techonologies (example - coolants) or different base product (example - DoT 4 & DoT 5 brake fluids), not due to the stepped-up supercession of technical specs within a line. Transmissions die from heat, contamination, lack of maintenance, and driving habits. They get moisture in them (through their breathers). An out-of-adjustment clutch will eat up synchros! Just routine gear wear ads to synchro strain. And everyone of us misses shifts and grinds the gears on occassion. Nothing is forever; synchros are actually a wear service item.