did the 10000 mile service on mine Saturday night, late night, tired..but wanted to get it done...dumped 20w 50 into the transmission and dumped my gear lube in the primary, drained the primary back out and refilled it with 20W 50 and called it good. i did catch the gear lube back into the quart bottle but was to tired. i figure it will be fine anyhow..but i was not sure if 75w 90 in the primary would be a good idea? anyone know how it would effect the clutch?