Old rear-engine VW transaxle

[Jimbo]

What gear oil would be best for a transaxle with yellow-metal syncros and a spiral-bevel ring and pinion? This is a 1969 VW. The owners manual calls for SAE 90 hypoid oil, but these things are known for short syncro life. I'm double-clutching second. Do spiral bevel gears have tooth pressures as high as hypoid gears? Redline MT-90 looks interesting, but is GL-4, not 5.

 

[ConfederateTyrant]

I know Castrol makes an 80w-90 hypoid gear oil. I would suggest a synthetic 75w-90 gear oil, but make sure it has the same recommendations as the manufacturer. The multi-viscosity oils won't cause any harm in a straight weight application.

 

[unDummy]

Don't worry about protection level. If you want GL5, then use one of the manual transmission or synchro friendly GL5s.

Redline 75w90NS
Motul Gear 300
Amsoil AGL
Royal Purple Maxgear
Synlube MT 75w90

And, don't fear the GL4 gear oils. Amsoil MTG and Redline MT90 are excellent and should protect well.

 

[mechtech2]

If you mean helical gears [spiral], then they are less loaded than hypoid, for sure.

 

[Jimbo]

After looking at it and seeing a little seepage, nix the idea of using syn. I put in Castrol Hypoy C 80W-90, which is GL-5 MT-1. The stuff is dark, stinky and probably not yellow-metal freindly, but I dont want leaks. The reason I think it is spiral-bevel is because the pinion gear centerline intersects the ring gear centerline. Every hypoid axle ive seen had an offset pinion.

 

[rt_ponder]

MT-1...is yellow metal friendly GL-5 gear lube, you'll do fine.

 

[ccs v2.0]

Quote:

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After looking at it and seeing a little seepage, nix the idea of using syn. I put in Castrol Hypoy C 80W-90, which is GL-5 MT-1. The stuff is dark, stinky and probably not yellow-metal freindly, but I dont want leaks. The reason I think it is spiral-bevel is because the pinion gear centerline intersects the ring gear centerline. Every hypoid axle ive seen had an offset pinion.

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This doesn't sound right. What kind of stink? Sulfur?

I'd personally use a GL-4. Sta-Lube makes a dino based GL-4 gear oil that some NAPAs carry. I don't care how buffered a new GL-4/5 may be, additives wear off.

 

[Jimbo]

Its the same stink from sulfur-phosphorus EP additives in hypoid oils I remember from decades ago. Synthetics ive used more recently, Mobil 1 and Redline are almost clear and dont smell as strong, but still have a hint of "garlic" odor. Redline MTL (GL-4) is more like a thick ATF.

 

[ccs v2.0]

Then I'd replace the Castrol on a regular basis (depending on the size of the leak, this may be moot).

 

[mechtech2]

The old VWs have hypoid gears in the final drive, but are not highly loaded because of the low power of the engine.
A true GL5 gear oil is recommended, but in reality you can use GL4,GL4-5.

 

[MolaKule]

Jimbo,

I saw a Yellow 1969 Beetle do 81 mph in the quarter mile this weekend.

I doubt he had the orignal engine in there, but it was fun to watch.

 

[glxpassat]

This site has some good info. His favorite is the Sta-lube GL-4 that you can get a Napa.

 

[ewetho]

Friends 66 Kharman Ghia which ran 1.000 to 60' and 11.85 in the 1/4 used off the shelf 80W90 GL5 in it and ran GREAT. Noted the 60' time at a regional NHRA door slammer event when one of them had to see the time slip and found we were in the middle of their class for 60'. Then ad to show them VW emblem on the block for them to believe it was a VW not a Porsche.

We used that in the shop all the time for those VeeDubs. It went in my 71 Super Beetle too. They are forgiving little transmissions that is for sure.