some do , but syn in the primary will usually slip the clutch , and syn or motor oil itself is not gear oil ..
So I use motor oil in the motor , my aftermarket clutch plates suggest light weight non synthetic motor oil , and the transmission has gears in it , so I use .............. wala gear oil ..
And after doing this all my life , I DO NOT follow the recommended fluid change ..
I change the motor and primary every oil change and the transmission , every other oil change ..
Oil is cheep ..
So Many Highways So Little Time