OK, well this is very important indeed. I don’t want to advise based on just your description. The OMC “premium blend” lube MUST be used in the electric shift gearcases. Mechanical shift gearcases were introduced in 1978. So, we must confirm which style lower gearcase your friend has.
One easy way to tell is looking at the propeller. Does the propeller have a black plastic cone on it with a cotter pin through it? If so, it is indeed and electric shift gearcase and must use the OMC premium blend in the lower gearcase. Using a heavier lube could cause the magnetic spring clutches to slip and damaged the unit permanently. The hi vis/heavier lube can be used in the upper gearcase, the horizontal ball shaft housing, and the tilt clutch system.
If your friend has a thru hub exhaust propeller, this means he has a 78 or newer unit which is manual shift. The hi vis/heavier lubes should be used in the lower gearcase as well as the other systems mentioned earlier.
Does your friend have the proper tools/oil pumps to do this job? Trying to use squeeze tubes to fill this big unit will be near impossible. This is not a particularly hard job, but it must be done right to avoid introducing a leak or underfilling the unit and damaging it permanently.
Again, there are four different housing/systems that must have the lube checked/changed on these units.
Lower gearcase
Upper gearcase
Tilt clutch
Horizontal ball shaft housing
Again, I don’t recommend doing this yourself/his self unless he has had previous experience with these units and the proper pressurize fill tank to do the job properly.
Post pictures of the unit if you/he are unsure whether your OMC stern drive is manual or electric shift.
