GL 4 or GL 5 - "Official Gear Lube Topic"

[EVfun]

[ORANGECRUSHer]

Does anyone use the sychromesh types? I have a side shift 091 out of a vanagon in my woodsbuggy and I believe I originally filled it up with Penzoil synchromesh when I first got it years ago. It's coming time to do it again and also the standard type 1 transaxle in my baja.

Do I really need synchromesh for that 091? Or can I just get the same oil for both boxes and keep it simple. I like valvoline products and they have a synchromesh product that advertises good compatibility with yellow metals. Would it be ok to run in my bug box and my 091?

https://shop.valvolineglobal.com/products/synchrom...G1cCxN2B0f

edit added datasheet:
https://sharena21.springcm.com/Public/Document/184...162d889bd3
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Brian H.

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[mukluk]

[Wildthings]

[mukluk]

[EVfun]

When my buggy was an electric vehicle I was running Redline MTL, which is a 75W80 weight GL-4 gear oil. It didn't seem to cause any issues.
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[Bruce]

[Bruce]

[Wildthings]

[Bruce]

[kvasilak]

My 65 has a bad 2nd gear synchro. I bought the car in May, changed the fluid before I drove it.
I used a good GL-5 that was safe for brass.
I could not shift into second at at speed above like 5mph without really bad grinding, down shifting was not possible.
Double clutching worked fine and yes the shifter was adjusted properly and Ive replaced the bushing and the coupler. It feels good ( for a VW )

I switched to Red Line MT-90 75W-90 GL-4. the GL5 that had maybe 200 miles on it was pretty black. I think I'll just call it a flush! lol
What a difference. second gear is now useable if youre nice and slow and don't rev it too high. Down shifting is still a nogo unless you're going really slow.

All in all it was worth it. Shifts better and less gear grinding.
But I'll still have to rev match on down shifts

[Wildthings]

[jim martin]

I don't see why there is so much confusion , I would just go like this .
any kind of stock or low abuse use a quality GL4 like amsoil transaxle and gear lube ,there will not be enough load to cause premature wear , if you are worried about it or loading your trans hard on the street or strip and also consider vehicle weight ,move up to the extra EP additives in a GL5.

both GL4 and GL5 both contain EP additives, in a GL5 the EP additives are obvious much higher. think of it this way in simple terms, with a hypoid gear set there is a wiping/sliding action just like in a air-cooled motor there is a wiping/sliding action with the cam and lifters ,we use zinc in the motor oil to bond to bare metals and make a protective layer to hopefully stop lifter/cam wear .no one seams to have a issue with this .

the same is done with the EP additives in GL5 oil it bonds to the gears and make a protective layer to hopefully stop metal to metal contact while still allowing the components to wipe and slide .
But the problem was either the EP additive was just to slippery and the synchros/syncro hubs could not do there job of equalizing speed or the protective EP layer would attach to the yellow metals / syncs and would actually pull some of that metal away with them when loaded causing premature wear , just not a big issue with steel.

So really simple .read the labels and know your intended use .there is no reason to debate the hell outa this and point fingers .
there are quite a few gl-5 oils that are now modified to allow the superior gear protection with the added EP additives but still allow correct synchro operation and are also not harmful to yellow metals .
torco, redline, lat to name a few .
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[kvasilak]

My 65 has a bad 2nd gear synchro. I bought the car in May, changed the fluid before I drove it.
I used a good GL-5 that was safe for brass.
I could not shift into second at at speed above like 5mph without really bad grinding, down shifting was not possible.
Double clutching worked fine and yes the shifter was adjusted properly and Ive replaced the bushing and the coupler. It feels good ( for a VW )

I switched to Red Line MT-90 75W-90 GL-4. the GL5 that had maybe 200 miles on it was pretty black. I think I'll just call it a flush! lol
What a difference. second gear is now useable if youre nice and slow and don't rev it too high. Down shifting is still a nogo unless you're going really slow.

All in all it was worth it. Shifts better and less gear grinding.
A month later and it's still better that the GL5
But I'll still have to rev match on down shifts

[Nitramrebrab72]

GL4 and GL5 are different load ratings. They can be obtained by a synthesised molecular modified oil , a full synthetic oil built up from scratch or plain mineral oil. All three may have additives to help. Mineral based will always have additives to reach GL5 that may pass the limits of being categorised as yellow metal safe. Some high quality fully synthetic GL5 oils will have less additives than a GL 4 mineral oil so will be even more yellow metal friendly.
Also to be noted for the corrosion to happen you need 3 things humidity, excessive additives and exposure to oxygen and quite possibly heat. If you remove any of the 3 it is difficult for there to be any corrosion. If a gear box is running regularly the oil will be a barrier(as it designed to stay stuck to the surface once parked up quite a while so no oxygen. If it runs regular medium to long runs then there will be no humidity and no oxygen as the gearbox is getting up to temperature as well as being covered with oil while parked. I am not saying to run excessive additive GL5 oils but pointing out why some people with unsafe GL5 will never have an issue with corrosion and some do.
Also to be noted the SAE J306 rating for gearbox oils has been modified 7 times since 1977 and quite often the oil has been thinned out ever time. The lowest viscosity for a modern marketed as a 80W90 category is almost half (13mm2@100°C) of what the highest viscosity was when the beetle came out of the same category oil (24mm@100°C). So I look for an oil close to the maximum 24mm2@100°C for the marketed category of oil which my also be found in a modern 75W140 marketing category of oil.

[jim martin]

[70bus]

To update this a bit, there was a good discussion here:
https://www.thesamba.com/vw/forum/viewtopic.php?t=798086
_________________
Craig K
70 Neunsitzer
65 Pritschenwagen
"If Von Dutch was alive, he'd walk in there with a pistol and shoot these people." - Robert Williams

Raul the 65 singlecab

Karl the 70 nine-seater

[my3bugs]

OK im almost 70 years old , reading some of this thread i call my local JIFFY and SPEEDY lube services to ask em what gear oil they would use in my VW beetles ...... i start asking if its GL4 and they hand ya off to the manager , what year , oh we dont work on old VW's , same answer from both places ........ so then i called VALVOLINE instant oil change , once i asked if they had GL4 they dont want to work on the VW's he says .....

3 out of 3 local oil change shops dont want our business ???? or dont want you to know what oil they use ?

one place said bring it down and i said not till i know what oil your gona use ? then i get the NO .


its been a while , i think i just used to buy 90 weight gear oil , prolly still have some out in the garage ....i was just want to make sure i got the new GL4 stuff you guys talk about here ........i can get it on amazon no problem .....

[SGKent]

Summit Racing has Joe Gibbs Driven 89W90 GL4 at a reasonable price. Next day delivery in many areas. My 77 bay shifts smoother and is quieter with it than Stalube 80W.
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[vamram]

The J. Gibbs Driven is a steal here at $15/quart.

https://www.drivenracingoil.com/products/conv-80w-...nt=**LP+TM
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