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I found old Mobil oil book and it said that the oil for 411/412 transmission is different kind than used in type 1.



SHC and HD are GL-5 oils, so what do you think should I use them? I´ve heard, that GL-5 oils is not good for transmission copper parts.

There are no copper parts in the 411/412 gearbox. I believe you are referring to brass. Its really hard to say what the alloy in the synchro rings of the 411/412 is. But...I will say this. All of the 411/412 4 speeds I have opened and disassembled and inspected has run for years, then sat for decades with the factory oils in them. I have never seen a speck of chemical related wear or damage other than corrosion on the case from water condensation. I think a lot of the issues about GL-5 oils I have been hearing about pertain to newer models of transmissions.

I have run everything from Castrol hypoy C to mixtures of basic SAE 90 with 10% moly additive.
Actually....I thought the moly additive caused issues from what I experienced. It may have been coincidence.
I also think that in the 411/412, multigrades have temeperature issues. I found less thinning and discoloration using straight 90.
In the summer heat I found the very best results using half SAE 90 and half SAE 140.
Short of a synthetic which I have not yet used in a type 4 tranny.....I have no real brand recommendation. Ray

I think I'll use Swepco 201 next time, just to see if it works as well for us as for porsche tranny's.

We´ll We have now GL-4 oil in the tranny. Should I replace the oil with GL5?