Hei.
Please do not use SAE140. The final drive recommends SAE90 and nowadays we use multigrade oil like 75W-90.
You may check mercedes-benz operating fluids. The final drive needs API GL5 hypoid. 235.0 is not longer supported and most current hypoid gear oils are fully synthetic, see current sheet 235.9
If you have a problem with your final gear drive with the recommended oil grade and quality (noise, heat, leakage) it is not a matter of oil.
For example you can use Mobil1 syn gear 75w-90 or comparable products from Shell, Castrol, whatever.
Talk soon, Martin