Recommended Lubricants

[boydpd]

Hi again - I'm about to change my manual transmission and differential oils. I know that the diff oil is a SAE 90W Hypoid gear oil. Any recommended types or brands?

Also, the manual trans uses a Type A Automatic Trans Fluid (according to Haynes). Once again, any recommended types or brands? I'm willing to pay for quality.

[Govert70227]

rear differential also 85W90

ATF type A is a very old specification, best go up a level: Dexron II or even higher, there are also specific manual gearbox oils.

MB has a site with officially recommended fluids: Mercedes-Benz Specifications for Operating Fluids: Engine Oil, Gear Oil, ATF, Coolant, Brakefluid but other brands not mentioned there can also be good.

[PlaneCrazy]

What would be specific gearbox oils?

I put 80w90 into my gearbox... turns out I shouldn't have. Visited the site linked above, but couldn't understand anything, other than that the Unimogs have a unique specification.

Would Dexron III be good? If not, what would be? Synthetic?

I read many of the posts returned by the "search this forum", but all I see are discussions and opinions, nothing I could put a finger on...

[Govert70227]

If you want to follow the "official" route, first look in the Service Manual for the specific lubricant code. The motor oil code for the W123 is 229.1 for instance. Now click on 229.1 on the lubricant page and then you can see the recommended lubricants. You only have to select the desired viscosity.

The manual of the car also has a list of recommended lubricants.

Manual gearboxes of the W123 originally have a ATF type A requirement, but specific gear oils (235.1) are also used (also by MB dealerships), especially on worn-out gearboxes. I have used both and have noticed no difference. Type A is very viscous when cold, newer standards (Dexron II and III) are better in cold weather.

Dexron II is OK according to the

Technical Companion

Technical Companion

of the MB Club USA, I don't know about Dexron III.

[boydpd]

Originally Posted by PlaneCrazy

I put 80w90 into my gearbox... turns out I shouldn't have. Visited the site linked above, but couldn't understand anything, other than that the Unimogs have a unique specification.

I bought 80w90 for my differential.. I haven't put it in yet, but I was planning to. Is this kosher?

Waiting another 5k till I do my transmission. The lubricant in it looks real good.

[Govert70227]

Recommended viscosity for rear differential is SAE 90 or SAE 85W-90. 80W-90 is widely used in W123s, but it is less viscous than it should be. I have yet to see a MB recommendation for 80W-90 for rear differentials.