Re: OMC Cobra drive gear oil and motor oil
I also used the HiVis and just switched to the HPF at the recommendation of my local OMC shop. For motor oil I use Chevron Delo 400 straight 30 wt. If you have never drained and refilled a Cobra, you must follow the procedure in the manual, or you may wind up with an air bubble trapped inside, which will rise to the top and it will then be underfilled, which will wipe out the upper gears. Remove the top plug (on top of drive with dipstick), then remove bottom plug on lower unit (foward end of the "bullet"). Also remove the plug a little above that just below the cavitation plate. That is actually the fill hole. You have to get a pump that screws into the gear oil bottles. Replace the bottom most plug. Place the top plug with dipstick in the hole, do not screw in (allows a little extra fill to make up for air bubbles). Screw pump into hole just below cavitation plate. Pump slowly, should take about 2 qts. Check with top plug with dipstick. When full thread in top plug, quickly remove pump fitting, replace plug there. Then recheck level with top plug screwed in. Let it sit over night. Then crank engine (don't start it, and make sure to do this with the muffs on w/water to not burn impeller). Then check again. All this is to see if any air escaped and you may need to add some thru the top hole (top of drive). If OK,start engine on muffs let it run a while, and re-check. After running it the level may be a little high, but that is OK, just let it sit and re-check. Easier to do than to describe!! But you must do it right!!
