According to the manual for the Explorer the front axle, gearbox and transfer box use OMD 330. But what is it?
The translation says that it is SAE 50 oil but I think that this may be incorrect. The only thing I can find on it from past threads is this;
There are two SAE scales, one for gear oils and one for engine oils, that overlap. SAE 50 is in the top end of the engine scale, but is the same viscosity as SAE 90 in the gear scale. The difference seems to be the additives added to the base oil to make it most suitable for engine, straight gear or EP gear oil.
If OMD 330 is specified for gearboxes why would you use SAE 50 engine oil rather than SAE 90 (non EP) gear oil?