Heavier weight oil might work in warm climates but I wouldn't put it in north of Texas. Eaton specs 50 wt. synthetic in their 18 speeds.
On all Eaton-Fuller transmissions, the fill plug is on the left side of the transmission. You insert the drive end of a 1/2" socket into it, and turn it counterclockwise to unthread it. That's where the transmission oil goes. Eaton-Fuller recommends you use either 50W synthetic, or 80W if you're going with mineral oil.
50W if you're going synthetic (recommended), 80W if you're going mineral.
Eaton Fuller recommends 50W synthetic. Not sure about other transmission manufacturers.
50W synthetic, or 70W mineral oil.
If the converter is drained, then about 17 quarts of fluid will be used. 75W90 is the recommended transmission oil to be used.
The manual transmission uses SAE 80-90 weight gear oil.
Eaton-Fuller recommends either 50W synthetic or 80 weight mineral oil.
You shouldn't have to.
The five speed uses ATF+4. The eight speed uses a special oil for the 8hp 45 transmission.
Honda manual transmission oil, go to your Honda dealer.
If it's an Eaton Fuller, 50W synthetic or 80W mineral.
Transmission: Motorex Top Speed 15W50