What octane does a OMC 3.0L GM engine take?

[rawzville]

Does the OMC 3.0L GM engine take 87 octane or higher? Since I just bought the boat used, and it came with no owner's manual, I need help.

 

[JustJason]

Re: What octane does a OMC 3.0L GM engine take?

Should run fine on 87. If it knocks then check your timing and bump it back if you need to.

 

[CharlieB]

Re: What octane does a OMC 3.0L GM engine take?

The manufacturers of marine drives, whether I/O or OB's, sell their products WORLDWIDE.

Knowing that fuel quality may not be the best worldwide the manufacturers design their engines fuel requirements to the lowest grade fuel available.

87 octane should be fine for most all marine engines.

As Jason said, if you experience any problem with your particular engine, check the timing carefully. Many service manuals allow up to 4 degrees retarded timing to compensate for any spark knock or pinging caused by low grade fuels.

 

[Rocky_Road]

Re: What octane does a OMC 3.0L GM engine take?

The manual calls for 87...as everyone has noted.

Now...since there isn't that much price difference between 87, and 89...I use 89. Why? Because I can only get E-10 here...and phase seperation is a realtime issue. Phase seperation lowers the actual octane...and I like the 'odds' that I will avoid any (very expensive) detonation!

Happy boating!