getrag fluid

[BMWDUO]

recently bought a 69 GT that has been converted to 5 speed. would like to change the oil/fluid but do not know what is correct. any help?

[GTJIM]

Welcome to the OpelGT Community!

Check with your local BMW agency or a BMW manual at your local library!
They use a very similar Getrag 240/245 5-speed trans.

Just found this:

"Oil should be seen as an integral part of the transmission. When designing the transmission the load bearing capability of the oil is part of the calculation. We fill the BMW transmissions with SAE 90 GL 4 gear oil manufactured by Fuchs, a brand mainly found as an OEM supplier.
SAE 90-Oil should be used throughout the whole year. It is true that in winter the shifting will suffer at first from the thick oil, but it should improve during a very short ride. For those to whom this is disturbing, because they make many short trips, for example, can use 75w90 GL 4 in winter as an alternative. In summer it must be changed back to SAE 90 GL 4."

Also this:

Read the label:
In order to choose a gear oil, you have to CAREFULLY read the label. GL-4 is the recommended API rating (American Petroleum Institute) and SAE 80W90 is the correct weight to use. Sometimes GL-4 oils are identified by these other classifications:

MIL-L-2105 (US military spec)
501.50 (Volkswagen)
235.1 (Mercedes Benz)
Note that MIL-L-2105D and MIL-L-2105E, etc are not the same as MIL-L-2105.

If the label makes no mention of GL-4 then you've probably picked the wrong type of gear oil.


--------------------------------------------------------------------------------

GL-5:
So why is GL-5 so bad?

Oils are made from base stocks, refined and then mixed with additives to improve their performance. GL-5's incompatibility is due to the extreme pressure (EP) wear additives. To give the gear oil its EP rating, it's easiest to add a sulpher based additive like MoS2 (molybdenum disulphide) but the sulphur present in the oil (you can smell it) is responsible for eating the copper alloy used to make the synchros.

GL-4 differs from GL-5 by the amount these chemicals are mixed into the oil (1/2 to much less in GL-4). Since the same additives are present in GL-4, they will eat the synchros as well but at a point in time that is beyond the expected service life of the gear stack.

To get the GL-4 rating, the oil has to pass the ASTM D-130 test. This test determines how reactive the sulpher is against a polished copper strip. The strip is also subjected to heating to simulate the running conditions in the gear box.

Many people have put in a call to an oil manufacturer to ask them about the suitability of their GL-5 product for VW transaxles and received an inconclusive response. They may be told it's ok without any details to back it up. Likewise, they may have heard it's ok to use but the manufacturer won't confirm this because they haven't tested and proved it (cost and liability). The tech on the phone may not even know any better and since you are trying to match a modern oil formula to a 30 year old transmission, chances of getting an accurate confirmation is slim especially if his computer system comes up blank concerning your vehicle type.

To obtain GL-5 certification, the manufacturer does not have to pass the ASTM D-130 test. This is the main reason why you should avoid GL-5. So, if you put in a call to a manufacturer about their GL-5, that test result is what you want to verify.

Some people will claim that using GL-5 in a GL-4 spec transmission doesn't apply when the GL-5 is synthetic. This depends on the oil and cannot be generalized. However, it should be noted that many GL-5 synthetic gear oils do not use sulpher in their EP additive package and can pass ASTM D-130.

Even if the manuacturer states the gear lube is "non-corrosive", its viscosity index may be too slippery for the Getrag style synchros. This means that while the syncros won't corrode, the oil is not designed to grab the hub the way GL-4 does and the transmission will wear out another way.

As a final caution, some GL-5 formulas have been known to permanently coat the synchros in a manual transmission reducing its life by 50%.

So choosing a gear oil is both a matter of chemical and mechanical compatibility. In hindsight that seems obvious but the heat of the debate tends to cloud the issue.

[BQS4]

Not trying to knock what GTJim has posted, but, I think Gil recommends a synthetic oil for the 5-spds. He states this in the instructions you get from him.

[RallyBob]

I still like using the Redline MTL in any Opel tranny. It's GL-4 rated and synthetic. Works well in the 4-speeds, the Getrag 240's and even my ZF 5-speed. The ZF's are notoriously hard-shifting, yet with the MTL it shifts like a Getrag 240.

FWIW....

Bob

[GTJIM]

The sources I quoted barely mentioned synthetic gearbox oil, just warned about GL-5 synthetic gear oil - but Redline MTL looks good and is GL-4 rated:

"This 70W80 GL-4 Gear Oil (SAE 5W30/10W30 engine oil viscosity) is designed for use in manual transmissions and transaxles. Provides excellent protection of gears and synchronizers and its balanced slipperiness provides a perfect coefficient of friction, allowing easier shifting. Popular in many BMW transmissions."

Probably one which Gil recommends ... and Bob certainly does!

[trlmr]

Just about everything GTJim stated is correct. The only thing I would add is that the copper strip test mentioned is also conducted under a controlled amount of moisture present and a specific time. (to let the moisture react with the sulfur) The only reason I say this is if you change your oil yearly I don't think the corrosion will be an issue. So if you have GL5 oil in your trans don't panic thinking it has to be replaced this instant.

[BMWDUO]

Thanks for the help. This all corrosponds to what I recently read in a Studebaker publication cautioning against GL-5 but with no explanation other than syncro damage. Now I understand

[jmbinjax]

I purchased a Getrag 240 from OGTS a couple of years ago and they sent a quart of mobil 1 and the instructions stated to use nothing but synthetic. I've change the fluid a few times not knowing the history of the trans and always used the Mobil 1. I began having problems with the 2nd gear synchro when cold and was told the mobil 1 does not have friction modifier for manual transmissions. I switched to Redline MT90 and the difference is night and day.

[Bill Hoffmann]

I've been using Mobil 1 75W90 GL5 in my Getrag. I haven't had any problems, but having read this I think I will try Red Line. Does anyone know the capacity of the Getrag 240?

[timemachine]

Originally Posted by Bill Hoffmann I've been using Mobil 1 75W90 GL5 in my Getrag. I haven't had any problems, but having read this I think I will try Red Line. Does anyone know the capacity of the Getrag 240?

Bill,

I've been running Redline MTL in my stock gearbox and Redline 75-80 in the rear with no complaints and the change was a noticeable improvement. I don't know the capacity of the Getrag, but the Opel gearbox and diff hold just 2.5-3 PINTS each.

Jim

[opelwasp]

Originally Posted by Bill Hoffmann I've been using Mobil 1 75W90 GL5 in my Getrag. I haven't had any problems, but having read this I think I will try Red Line. Does anyone know the capacity of the Getrag 240?

I believe it is about 2 1/4 quarts, get 3. I use redline for ll my lubricants. Great improvement and the engine oil has ZDDP!

[BMWDUO]

Thanks for mentioningnZDDP!!!! This seems to be the key to keeping all older engines alive. Now if I can just find a local source for Redline products.
Thanks

[timemachine]

Originally Posted by BMWDUO Thanks for mentioningnZDDP!!!! This seems to be the key to keeping all older engines alive. Now if I can just find a local source for Redline products. Thanks

As far as I have learned (and as well reported in The Blitz), ZDDP is a crucial motor oil supplement to keep flat tappets and cam lobes intact. I'm on that road too.

But for differential and gearbox where things aren's as much heated and combustible, the Redline products previously mentioned are a good solution for most Opel users.

Jim

[Paul]

Originally Posted by BMWDUO Thanks for mentioningnZDDP!!!! This seems to be the key to keeping all older engines alive. Now if I can just find a local source for Redline products. Thanks

You can always purchase on line... try Racer Parts Wholesale - Award Winning Online Catalog For Real Racers

[markandson]

Originally Posted by Bill Hoffmann I've been using Mobil 1 75W90 GL5 in my Getrag. I haven't had any problems, but having read this I think I will try Red Line. Does anyone know the capacity of the Getrag 240?

I am installing my engine and 5spd at the moment and came up with this same question. When doing a web search it pointed to this thread and also to two other sites. One of the other sites says a Getrag 240 takes 1.2 quarts and another says 1.2 liters but either way it is not as much as suggested above so be careful.

[jmbinjax]

Capacity for a Getrag 240 is about 1 1/4 qts.

[opelenvy]

After installed the Getrag in my car I ran it to operating temp with a standard 90w gear oil. No, leaks, all looked good so I drained it out and filled the Getrag and the rear end with Red Line MTL. I drove around town some and noticed that it is leaking out the tailshaft. So I had Gil send me a new seal and installed it and cleaned everything up. I drove a couple miles and checked and it had new drips. I drove about 11 hours round trip this weekend to Wichita Falls, TX for our meet and all went well. I just looked under the car and I have a new coating of rust preventative. The tail pipe, muffler, and bottom of the car from the tail shaft back are coated in Red Line MTL.
Of course it is all burnt on the exhaust.
So...a new seal did not stop the leak. What now? I got the drive shaft from reputable Opel member and it was already made to fit. Is the shaft maybe a fraction smaller or something?

[markandson]

Originally Posted by opelenvy After installed the Getrag in my car I ran it to operating temp with a standard 90w gear oil. No, leaks, all looked good so I drained it out and filled the Getrag and the rear end with Red Line MTL. I drove around town some and noticed that it is leaking out the tailshaft. So I had Gil send me a new seal and installed it and cleaned everything up. I drove a couple miles and checked and it had new drips. I drove about 11 hours round trip this weekend to Wichita Falls, TX for our meet and all went well. I just looked under the car and I have a new coating of rust preventative. The tail pipe, muffler, and bottom of the car from the tail shaft back are coated in Red Line MTL. Of course it is all burnt on the exhaust. So...a new seal did not stop the leak. What now? I got the drive shaft from reputable Opel member and it was already made to fit. Is the shaft maybe a fraction smaller or something?

Make sure the shaft is not worn right where the seal rides, also it is important that the center bearing is in good condition as enough run out in the center bearing will pull the shaft against the seal too, this same thing applies to the bearings in the universal joint. If the output bearing on the getrag is bad you will also get the same effect. Last question......are you putting sealant on the OD of the seal when you install it?

[opelenvy]

Originally Posted by markandson Make sure the shaft is not worn right where the seal rides, also it is important that the center bearing is in good condition How would one check this?as enough run out in the center bearing will pull the shaft against the seal too, this same thing applies to the bearings in the universal joint.Universal joint is nice and tight. If the output bearing on the getrag is bad you will also get the same effect.again, how would I check? Last question......are you putting sealant on the OD of the seal when you install it?No, I did not.

See my comments in red above.