Oil

[beckoning]

I have 4 questions because the manuals I have don't specify:
1) Correct gear oil for bottom units on my 1988 100hp Merc (less than 1 pint) and 2010 9.9hp Merc (about 1 pint), and
2) Correct oil for 9.9 Merc 4-stroke. It is used 100 hrs/summer in Lake Michigan (45-70 degrees temp) at trolling speeds (less than 4mph), and
3) I cannot find an oil filter on the 9.9. Is there an oil filter or screen hidden somewhere that I should clean or change?
4) Is there something special about oil and lube packaged by Mercury? Its is 2X as expensive as automotive

 

[Yegboats]

Stick with Marine specific oils it doesn't have to be Mercury brand.

 

[MH Hawker]

marine oil has several additives the big on is for non foaming that helps keep the pressure lower

 

[jimmbo]

It is amazing how many people try to chinz out on oil. My uncles 'Expert Friend' kept telling him that 'oil is oil, and the stuff is only relabeled Auto Oil. Every second year his outdrive would grenade. After his last rebuild when he was winterizing it, I pointed out to him the drives always made it through the season after being rebuilt, but would always grenade when he had used what his friend said was 'the same stuff'. He opened his wallet, let the moths out and refilled with the marine oil, never blew the unit again. Of course his buddy went out of his way to say, the shop finally rebuilt it right...