Octane requirements for Merc 500's
 

Whats the suggested min octane for the Merc 500 hp efi, in my 2001 35 Lightning?? At our lake I see gas from 87 to 110. thanks, whip :drink:

Re: Octane requirements for Merc 500's
 

I run 87 oct have 400 hours never one problem, as long as their stock just 87 is fine.

WILL

Re: Octane requirements for Merc 500's
 

Yep, 87 octane. More octane and you are wasting your money and possibly losing power.

Re: Octane requirements for Merc 500's
 

The 87 will make more power in your boat

Re: Octane requirements for Merc 500's
 

I put 110 in a stock 502 carb and It had no top and at all.

Re: Octane requirements for Merc 500's
 

The lower Octane fuels burn faster, makes more power in low/comp engines. The high octane fuels burn slower for the high/compression motors.

Re: Octane requirements for Merc 500's
 

they will run on 87 with no problems ( the beauty of efi computers ) but prefer 89- 93

Re: Octane requirements for Merc 500's
 

I run 87 all the time, 530 hrs-no issues but when I can only find 93, it blackens the transom like crazy. Burns ok, runs ok-the computer changes your advance when it reads the difference but makes a mess of things.

500 EFI's-stock setup on a 38 Lightning.