Hi Adam
You have the same engine as me but the 50hp version.
Handbook says:
(Quote)
SAE 10W-30 viscosity oil is recommended for use in all temperatures.
SAE 25W-40 viscosity oil may be used at temperatures above 40F (4C)
Use Quicksilver or Mercury Precision Lubrucants 4-stroke outboard oil or 4-cycle marine engine oil with the proper viscosity for the expected temperature in your area.
If not available use a premium quality 4-cycle engine oil, certified to meet or exceed any one or combinations of the following American Petroleum Institute (API) Service Classification SH, SG, SF, CF-4, CE, CD, CD11
(End quote)
Seems like you can use a good quality car engine oil with out any problems.
Out of interest can you advise me how much the oil filter is as I need to carry out an oil change on my engine.
Regards
Coddy