2009 Yamaha F40 Outboard Service Manual, Page 361Get this manual
Maintenance
If the fluid is at the correct level, small amount of fluid should overflow out of the filler hole when the reservoir cap is removed3If the fluid is below the correct level, add the recommended fluid to bring it up to the correct level
Checking the propeller
1Check the propellerSee "Checking the propeller" (8-3)
Recommended PTT fluid: ATF Dexron II 4Install new O-ring and the reservoir cap b, and then tighten the reservoir cap to the specified torqueReservoir cap b: Nm (0.7 kgfm, 5.2 ftlb)