mercrusier 5.7l

[moonraker 36]

can't find mi engine manual...
so what engine oil would you recommend?
which plug's would you go for?

engine is merc 5.7l with thunderbolt ign. on quadrajet carb,
(just to give an idea of year of engine as i hav'nt got a clue).

cheers.......

 

[mercuryman]

Depends on the age of engine. With a quadra jet carb I'm guessing you are on short reach plugs. So NGK BR6FS.

Engine oil 10/40 semi synthetic. 25/40 if you can get it.

 

[moonraker 36]

thanks for quick reply mercuryman..
i would guess engine around the 1980's,i should no really as it was full rebuilt 4-5 yrs ago.
would you not recommend fully synthetic engine oil at all?