2005 Yamaha F90TR 90HP Outboards Factory Service Manual, Page 32Get this manual
Top cowlingFuel systemPower unit
Power unit
Checking the engine oil
1Place the outboard motor in an upright position2Remove the oil dipstick, wipe it clean, and then insert it back into the dipstick hole3Remove the oil dipstick again to check the oil level and to check the oil for discoloration and its viscosity
4Operate the oil changer to extract the oilNOTE: Be sure to clean up any oil spills5Pour the specified amount of the recommended engine oil into the oil filler holeRecommended engine oil: 4-stroke motor oil API: SE, SF, SG, SH, or SJ SAE: 10W-30 or 10W-40 Engine oil quantity: Without oil filter replacement: 4.3 (4.55 US qt, 3.78 Imp qt) 6Install the oil filler cap and oil dipstick, and then start the engine and warm it up for minutes7Turn the engine off, and then check the oil level and correct it if necessary