You didn't specify which year or model 250 you have, there are two different gearcases depending on the year or if one has been replaced with the other.
The L2 Lightning gearcase holds 32.5 oz.
The M2 Magnum gearcase holds 38.9 oz.
It would be best to post any other Evinrude E-TEC service questions or comments in the appropriate forum and not in this one.
-- Travis McGee, main character in a book series by John D. McDonald
The information offered here is only general in nature and should not be construed as complete factory approved procedures, techniques, or specifications. Always use the proper service manual for your motor, up-to-date service literature, the correct tools, and have an understanding of how to proceed with troubleshooting and repair methods. If you are unsure or uncomfortable with a procedure, a situation, or a technique, enlist the services of a factory trained technician.