20W-50 is equal to Sae 90 W.
Manual says to use SAE 75w-90 or SAE 80w-90 gear oil
SAE 90
The fire point of SAE 90 oil is typically around 280°C (536°F), which is the temperature at which the oil will sustain combustion. The flash point of SAE 90 oil is approximately 250°C (482°F), which is the temperature at which the oil will produce enough vapor to ignite momentarily in the presence of an ignition source.
Yes, you can use 75w-90 gear oil instead of SAE 90 gear oil
sae 90
Sae 75w/90
SAE 80 or SAE 80w-90 below 50 f SAE 90 or SAE 80w-90 0 to 90 f SAE 140 above 50 f consistently
Sae 80w-90 gl-5
The cross reference for m-4864 which is a hydraulic oil or transmission fluid is SAE 80 for below freezing temperatures. B (SAE 90) is used for temperatures that are above freezing.
90 weight oil corresponds to SAE 90 oil, which means it has a viscosity rating of 90. The weight of the oil is measured in centistokes at 100°C, which helps to determine how thick or thin the oil is. However, the weight of the oil in pounds depends on the volume of oil you are referring to.
SAE 75W-90
Do not use the oil instructed below.... 10w-30 is fine for mild climates. SAE 75W-90