1993 Johnson Evinrude "ET" 90 degrees CV Service Manual, P/N 508285, Page 324Get this manual
Routine Inspections
1Check reservoir fluid level at least once per season or every 50 operating hoursSystem capacity is approximately 25 flo oz(740 ml) Unit must be in vertical position Check fluid when trim and tilt cylinders are fully extended Add OMC Power TrimlTilt and Power Steering Fluid or GM Dexron" as needed to bring level up to the bottom of fill plug thread Loosely install fill plugCycle unit in ten second spurts (adding fluid as needed)A minimum of five complete cycles is required to purge air from the system
2Look for indications of internal fluid leakageCorrect the cause if leaks are noted