OK, I am a new boater and apparently have lots to learn... I have 3
or 4 questions for the experts:

a) My motor is a 1990 OMC Cobra 2.3L TwinCam (based on Ford engine).
Is it necessary to use specific MARINE engine oil or can I simply use
10W30? The book says "SAE30". However, it also says "OMC does not
recommend the use of 10W30 and 10W40 multi-viscocity oils". It is
unclear to me if they mean that I can't use 10W30 or the fact that
they don't recommend "multiviscocity" oils (whatever that may be)...
That is, it would be OK to use 10W30 as long as it is not the
multiviscocity type...

2) The book often refers to "solvent" as in "Wash the flame arrestor
in solvent and air dry thoroughly". What do they mean by solvent???

3) I also read "Proper oil pressure is vital to the engine; if oil
pressure is insufficient, the engine can destroy itself..." . Fair
enough! However, they do not tell me what it should be!!!! When I
first run the boat (say for the first 5 minutes, Oil pressure is
around 55-60 psi and then it settles in the 30 - 40 psi (at 40 the oil
pressure needle is in the middle of the display). Does that seems
about right??

4) To grease the gimball bearing (the hole seems to be on the
starboard side of the lower unit) can I simply use 3 Guard grease? If
not, what should I use?

I may not know much but I understand that is is important to regularly
maintain the boat so that it keeps running problem-free so I am keen
to learn about basic maintenance. Other suggestions are most welcome!

Andre