90 grade gear oils used to refers to [email protected]
range from 13.5 to 24.0 cSt, in gear oil speak is ranging from ISO 150 to ISO 320 gear oils.
SAE 90, being monograde, falls into ISO 220-320, whilst multigrade say, 80W90 falls into ISO 150 to ISO 220 gear oils.
Post 2005, the single 90 grade were divided into 2 categories. Namely current day SAE 90 AND uncommon SAE 110.
Hence in literal translation(?), a pre-2005 monograde SAE 90 should be directly equivalent to (uncommon) current SAE 110 whose [email protected]
*V ranges from 220 cSt to 320 cSt.
Current day 75W90 is basically an ISO 100 gear oil with [email protected]
*C of 100 cSt thereabout.