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pastellgreen
Samba Member
Joined: January 06, 2012
Posts: 1126
Location: Germany
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 Posted: Sat May 17, 2025 6:10 am Post subject: Re: Transmission oil? |
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| Glenn wrote: |
| pastellgreen wrote: |
| simply use the oil VW recommended to use and used itself. Is it really that hard? |
That was a lot of years ago and things change... usually for the better. Oil today is better formulated than it was in the 50's.
When light bulbs need to be replaced, in your house, do you insist on finding incandescent bulbs or do you use LEDs? |
VW also updated their recommendations over the decades. They started with SAE90 and ended up with SAE 80W90 in the 70's. I assume this recommendation was vaild until the end. The last note from VW I have at hand concerning our aircooled cars is from 1996.
The fact oil itself has changed over that long time is clear to me and we can be happy when we find it better formulated today. But nevertheless I would not doubt the specificated viscosity class as this is the only reference the supplier and user are working with. As long we have an exact specification from VW and the material defined is available (even better formulated), why should one not use it?
Last edited by pastellgreen on Sat May 17, 2025 6:17 am; edited 2 times in total |
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Glenn 
Mr. 010
Joined: December 25, 2001
Posts: 79221
Location: Sneaking up behind you
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| Posted: Sat May 17, 2025 6:12 am Post subject: Re: Transmission oil? |
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| pastellgreen wrote: |
| Glenn wrote: |
| pastellgreen wrote: |
| simply use the oil VW recommended to use and used itself. Is it really that hard? |
That was a lot of years ago and things change... usually for the better. Oil today is better formulated than it was in the 50's.
When light bulbs need to be replaced, in your house, do you insist on finding incandescent bulbs or do you use LEDs? |
VW also updated their recommendations over the decades. They started with SAE90 and ended up with SAE 80W90 in the 70's. I assume this recommendation was vaild until the end. The last note from VW I have at hand concerning our aircooled cars is from 1996.
The fact oil itself has changed over that long time is clear to me and we can be happy when we find it better formulated today. But nevertheless I would not doubt the specificated viscosity class as this is the only reference the supplier and user work with. |
But VW never expected these car to still be on the road 50+ years later.
_________________
Glenn
74 Beetle Specs | 74 Beetle Restoration | 2180cc Engine
"You may not get what you pay for, but you always pay for what you get"
Member #1009
#BlueSquare
עַם יִשְׂרָאֵל חַי |
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wagen19
Samba Member
Joined: November 16, 2007
Posts: 543
Location: germany
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| Posted: Sat May 17, 2025 6:15 am Post subject: Re: Transmission oil? |
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| Glenn wrote: |
| pastellgreen wrote: |
| simply use the oil VW recommended to use and used itself. Is it really that hard? |
That was a lot of years ago and things change... usually for the better. Oil today is better formulated than it was in the 50's. |
The choice of oil...
Is there "wrong or bad transmission oil" for our cars on the market?
What kind of trans-issues caused by "wrong oil" are known?
For many owner and enthusiasts of (old) vehicles, it´s more a question of faith, than based on (actual) technical knowledge or proven facts.
Even if you believe and realize the better technical characteristics of modern oils, the question and fear remains, modern additives can eventually cause issues on old materials of gaskets, seals and all inner parts of transmissions (or engines).
In practice, there are some people who are filling in the cheapest transmission oils at hand and don´t worry about. Does this cause significant transmission issues, and if so, which ones?
What about torque, power, revs, temperature in our transmissions, compared to modern cars?
Can some of the transmission mechanics give a contribution of known issues, failures due to "wrong oil"? Thinking about possible aggressive chemical additives?
In general, what kind of transmission issues, failures, problems are known from practice?
Leaking, worn out bearings and gears, synchro rings, broken diff cases etc.
Imo, the old 307 and 309 splitted cases tend to leak. Some aftermarket axle boots detoriate sooner than others.
Can we expect that VW or Porsche will have long term test runs with our old and used aggregates whether they tolerate modern oils? Who is willing to lean out of the window for updates without tests?
It´s easy to find out, cold oil is stiffer and increases fuel consumption and reduces power on wheels.
I suggest to post stories and pics of defective transmission parts here, so we can discuss, whether "wrong oil" was the culprit.
Next question is, which oil, what kind of oil (mineral, synthetic) was used in our old, or modern transmissions which had properly ran 250 000 miles plus? |
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pastellgreen
Samba Member
Joined: January 06, 2012
Posts: 1126
Location: Germany
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| Posted: Sat May 17, 2025 6:18 am Post subject: Re: Transmission oil? |
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| As long we have an exact specification from VW and the material defined is available (even better formulated), why should one not use it? |
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Glenn
Mr. 010
Joined: December 25, 2001
Posts: 79221
Location: Sneaking up behind you
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| Posted: Sat May 17, 2025 6:29 am Post subject: Re: Transmission oil? |
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Is suggest you listen to Bruce since he actually works on transaxles and has real experience.
I rather take advice from the horses mouth than the other end of the animal.
Since my 50+ years of experience is related to IRS transaxles... I offer no direct recommendation.
_________________
Glenn
74 Beetle Specs | 74 Beetle Restoration | 2180cc Engine
"You may not get what you pay for, but you always pay for what you get"
Member #1009
#BlueSquare
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Glenn
Mr. 010
Joined: December 25, 2001
Posts: 79221
Location: Sneaking up behind you
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| Posted: Sat May 17, 2025 6:31 am Post subject: Re: Transmission oil? |
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| wagen19 wrote: |
| Next question is, which oil, what kind of oil (mineral, synthetic) was used in our old, or modern transmissions which had properly ran 250 000 miles plus? |
Most 60+year old VWs have had their transaxles rebuilt and never reached 250,000 miles on the original build.
_________________
Glenn
74 Beetle Specs | 74 Beetle Restoration | 2180cc Engine
"You may not get what you pay for, but you always pay for what you get"
Member #1009
#BlueSquare
עַם יִשְׂרָאֵל חַי |
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esde
Samba Member
Joined: October 20, 2007
Posts: 6289
Location: central rust belt
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| Posted: Sat May 17, 2025 7:38 am Post subject: Re: Transmission oil? |
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VW's updated spec to 80-90 was probably because the lighter oil was better at reaching some of the areas that receive poor circulation.
On the non synchro first boxes, there are several areas that receive inadequate lubrication. I base this on the last 20 core transmissions I've torn down for parts..
Differential side gears and fulcrum plates
center bushing for the 3/4 hub assembly
brass bushing for the 1/2 hub assembly (not as often as 3/4)
So, the solution for this is to either use a thinner lube or improve lubrication feed to these areas. I modify the hub assemblies for better lubrication when I rebuild early boxes, but not everyone can do this. So maybe just use a thinner oil?
But, the early gear boxes use ball bearings, not roller bearings (like later transmissions) Ball bearings have different lubrication needs as they are loaded differently.
So, if you want to have the best of both worlds you use a good synthetic oil like the Redline or Amsoil. They pour like a thinner oil but meet the specs of a heavier oil.
For sure, I have run 75-90 on cars with success. Every car I have used Redline in has run quieter and shifted better, and that says something. Though, none of the transmissions I've rebuilt or filled with Redline see high miles so I do not have real world long term data.
SD
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modok wrote:
Bent cranks are silent but gather no moss. I mean, ah, something like that. |
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mr matt
Samba Member
Joined: May 26, 2005
Posts: 961
Location: southeast Pa
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| Posted: Sat May 17, 2025 9:04 am Post subject: Re: Transmission oil? |
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I have read the 70+ pages on oil, and was hoping this topic would not be too much an addendum to that.. some is natural. Seems like either the redline which i bought is good, so happy with that... and likely the other oil I posted would have been fine.. but am going with the crowd for redline on this.
My car is a 1955, transaxle has never been rebuilt. I has been in storage for about 20 years somewhere in its life, and has not been driven much, but I am still impressed. There is a little grind going into 2nd gear, but that is it.
Outside of the oil discussion that started, my other question was going to be this...
Ok, the axle boot cracked, and appeared to happen over winter in the car's small garage ( always pays to have layers of cardboard under the car..) but what would have happened if this happened on a long trip..is it possible to lose enough tran oil through a cracked boot to ruin your transaxle on a drive?
I hope there would be enough oil in the tranny for it not to be a suicide... and I hope the German engineers would have anticipated this possible fault and consequence.
_________________
1955 3-fold semaphore Oval beetle
1971 Convertible beetle
1977 Westfalia, FI, Berlin interior |
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wagen19
Samba Member
Joined: November 16, 2007
Posts: 543
Location: germany
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| Posted: Sat May 17, 2025 9:11 am Post subject: Re: Transmission oil? |
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| esde wrote: |
VW's updated spec to 80-90 was probably because the lighter oil was better at reaching some of the areas that receive poor circulation.
On the non synchro first boxes, there are several areas that receive inadequate lubrication. I base this on the last 20 core transmissions I've torn down for parts..
Differential side gears and fulcrum plates
center bushing for the 3/4 hub assembly
brass bushing for the 1/2 hub assembly (not as often as 3/4)
So, the solution for this is to either use a thinner lube or improve lubrication feed to these areas. I modify the hub assemblies for better lubrication when I rebuild early boxes, but not everyone can do this. So maybe just use a thinner oil?
But, the early gear boxes use ball bearings, not roller bearings (like later transmissions) Ball bearings have different lubrication needs as they are loaded differently.
So, if you want to have the best of both worlds you use a good synthetic oil like the Redline or Amsoil. They pour like a thinner oil but meet the specs of a heavier oil.
For sure, I have run 75-90 on cars with success. Every car I have used Redline in has run quieter and shifted better, and that says something. Though, none of the transmissions I've rebuilt or filled with Redline see high miles so I do not have real world long term data.
SD |
Thank you for your post.
It´s also my conviction, the oil should be as thin as possible, but as thick or heavy as needed.
At least many modern transmissions can reach untouched easily 250 000 miles, if not 500 000. (even often a oil change is not recommended, maybe thought for 10 years)
Synthetic oils:
Thinking about a CU vanagon engine with hydraulic lifters. Filled with mineral 20 W-50 or full synthetic 10 W-60. The time after cold start while running with noisy lifters is significant shorter with thinner synthetic oil. It´s also designed for a higher oil temperature. Engine inside remains very clean. No problems with leaking.
Have you asked your seller of "your" synthetic transmission oil, if he recommends it for our old type 307, 309 and 311 transmissions?
Are there any risks or issues, for ex with leaking cases or axle boots known?
How many years or miles lasts your experience with 307, 309 trans?
Thank you |
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wagen19
Samba Member
Joined: November 16, 2007
Posts: 543
Location: germany
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| Posted: Sat May 17, 2025 9:26 am Post subject: Re: Transmission oil? |
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| mr matt wrote: |
I have read the 70+ pages on oil, and was hoping this topic would not be too much an addendum to that.. some is natural. Seems like either the redline which i bought is good, so happy with that... and likely the other oil I posted would have been fine.. but am going with the crowd for redline on this.
My car is a 1955, transaxle has never been rebuilt. I has been in storage for about 20 years somewhere in its life, and has not been driven much, but I am still impressed. There is a little grind going into 2nd gear, but that is it.
Outside of the oil discussion that started, my other question was going to be this...
Ok, the axle boot cracked, and appeared to happen over winter in the car's small garage ( always pays to have layers of cardboard under the car..) but what would have happened if this happened on a long trip..is it possible to lose enough tran oil through a cracked boot to ruin your transaxle on a drive?
I hope there would be enough oil in the tranny for it not to be a suicide... and I hope the German engineers would have anticipated this possible fault and consequence. |
If there was enough oil inside your trans and "only" the boots are cracked, there is still plenty of oil inside the trans. Think about the position of the filling plug. Only up to that level oil can be filled in. When the main shaft turns, then also some gears on drive shaft. So the oil "gets around" inside. So it´s hardly a big problem. I know, some cars had ran thousands of miles with cracked axle boots before the boots were replaced and the oil was changed or at least filled up. |
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esde
Samba Member
Joined: October 20, 2007
Posts: 6289
Location: central rust belt
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| Posted: Sat May 17, 2025 11:05 am Post subject: Re: Transmission oil? |
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| wagen19 wrote: |
Have you asked your seller of "your" synthetic transmission oil, if he recommends it for our old type 307, 309 and 311 transmissions?
Are there any risks or issues, for ex with leaking cases or axle boots known?
How many years or miles lasts your experience with 307, 309 trans?
Thank you |
I have not inquired with Redline or Amsoil specifically about the VW transmissions. But, 20 years ago when I was rebuilding a Mercedes Unimog transmission, I did go deep down the rabbit hole with Amsoil techs regarding synthetic oil weight, GL spec, and how it related to the internal components. I did learn enough to feel confident using synthetics, with a basic understanding of why they are better. As for leakage, my experience is if it leaks it's gonna leak no matter what type of oil it's filled with.
I've only been rebuilding the split case transmissions for a few years now, but I've done more than a handful of tunnel type swingaxle units.
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modok wrote:
Bent cranks are silent but gather no moss. I mean, ah, something like that. |
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BulliBill
Samba Member
Joined: July 09, 2004
Posts: 4739
Location: St Charles, MO
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| Posted: Mon May 19, 2025 3:39 pm Post subject: Re: Transmission oil? |
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I'm a GL-4 fan! I've used it in most of my VW fleet for over forty years...
Bill
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I'm looking for these license plate frames for my fleet:
Coeur D'Alene - Lake Shore Volkswagen
Mission VW - San Fernando
Thornton VW - Stockton
Thanks for any help! |
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mr matt
Samba Member
Joined: May 26, 2005
Posts: 961
Location: southeast Pa
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| Posted: Thu May 22, 2025 12:34 pm Post subject: Re: Transmission oil? |
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When I drained my tran fluid, I missed the opportunity to measure how much fluid is left in the tranny from a bottom cracked axle boot.. From memory looking how much was in very large pan.. it seemed like 1 quart.
Least the oil was a nice golden brown when it came out, and really nothing on the magnetic plugs
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1955 3-fold semaphore Oval beetle
1971 Convertible beetle
1977 Westfalia, FI, Berlin interior |
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rglsr
Samba Member
Joined: December 06, 2004
Posts: 25
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| Posted: Thu May 22, 2025 3:03 pm Post subject: Re: Transmission oil? |
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I started using Liquid Moly 85W-90 GL4 when Stalube stopped selling quart bottles, been holding up fine in my OG 1955 split case (never out of car)
https://www.liqui-moly.com/en/us/gear-oil-gl4-sae-...VcjX#20016
I have used Redline MT90 in other cars (not old VWs) also very good manual trans oil. As others mentioned shifting smoother, etc. I'm sure it would be fine in an old VW, I never felt the need, and its 2X the price. |
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