Cobra sterndrive has one cavity where the oil is stored, so all the oil in the
upper and lower gearcase must be changed and filled at the same time.
these easy steps to change the oil in your drive.
If you have not yet drained your oil,
see our Draining your OMC Cobra's oil help page before filling your sterndrive with oil. To view technical drawings for upper and lower gearcases, see your I need help page.
Start off by locating the lower drain screw/plug on the lower gearcase. (It is on the starboard side of the lower unit on the cone - shown in photo).
Remove this plug using the
largest blade flathead screwdriver available. Insert your oil pump as snug as possible into the drain hole.
Lower gearcase upper drain screw location
Lower gearcase upper drain screw
Locate the upper drain screw/plug (shown in photo), and remove it using the same flathead screwdriver you used to remove
the lower drain screw.
Begin pumping oil into the lower drain hole, and carefully watch the upper drain hole until
you see the oil reach this level. When the oil just reaches the upper drain hole, close it up by inserting the upper drain
(DO NOT STRIP the screw when making sure it is tight enough)
Lower unit oil pump
Lower unit oil pump
Remove the oil pump from the lower drain hole, and quickly insert the drain screw/plug.
the drain screw from the
upper portion of the lower gearcase, and
quickly insert the oil pump into the upper drain hole.
Begin pumping oil to proper level on upper
gearcase dip stick.
28404 cover o-ring
Dip stick location
On the top side of the upper gearcase, you will see a cover, with four large bolts attached to it. In the center of this cover or cap, you will see a 3/4"
diameter flathead dipstick.
Remove it, and note where the oil level is. The oil level on an Cobra should
be at the line on the dipstick. If it is not at this line, keep pumping in oil through the lower units upper drain hole.
When the oil reaches the line, put the dipstick back in. Remove the oil pump, and quickly insert the lower
units upper drain plug. Make sure this screw/plug is tight, but be careful not to strip the screw.