The Jaguar XKE (as well as XK 150, 140, and 120. MGB also) called for 30 wt motor oil in the transmission.. When ya talk gear oils, the "weight" number is not the same weight number as motor oils.. For instance, viscosity is measured in Saybolt Seconds Universal (or centistokes). The specification for 30 wt motor oil is 58-70 SSU measured at 210 F (9.6-12.9 centistokes). The specification for 85 wt gear oil is 63 min SSU, measured at 210 F (11, minimum centistokes), in the same range as 30 wt engine oil. . Yes, the additive packages are different,with gear oils generally having additives to work successfully with hypoid gears (rear differentials with the drive gear offset below the axle centerline). Hypoid gears in particular have a lot more sliding at the tooth interface than do spur type gears as in say a Kanzaki .. The additives are strange in that they put a micro-coat of corrosion products on the tooth faces. The corrosion products are very hard and that is basically how they work. There are some very hard steels in the gears of a typical rear differential. They can stand (and are designed to) the aggressive action of the EP additives. Some/most extreme pressure additives in gear oils will attack bronze, which is what half of the cone clutch is made of in a Kanzaki. This is why Yanmar does not tell you to use gear oil. The gears, bearings and tooth face sizes in the Kanzaki are designed to work with an engine oil without the need for EP additives.
ATF, another animal entirely, has an approx vis of 7.8 centistokes, abut the same as 20 wt engine oil.. It is called for in transmissions that have disk (not cone) clutches as in an automobile automatic and many Kanzaki models and many Hurth models. .. Look at the plate on your transmission and use that oil.. If it uses a "retired" or obsolete engine oil rating, like CD, the newer ratings CE, CF, etc are generally superior to the older rating..
End Of Rant.. Google my facts to check if you'd like..
ATF, another animal entirely, has an approx vis of 7.8 centistokes, abut the same as 20 wt engine oil.. It is called for in transmissions that have disk (not cone) clutches as in an automobile automatic and many Kanzaki models and many Hurth models. .. Look at the plate on your transmission and use that oil.. If it uses a "retired" or obsolete engine oil rating, like CD, the newer ratings CE, CF, etc are generally superior to the older rating..
End Of Rant.. Google my facts to check if you'd like..