87 Octane in a EFI Merc?

[MakoNY]

Can I use 87 octane gas in a '99 Merc 250 EFI?

I was told to run at least 89 but that 93 was preferable, and that 93 runs a bit cooler.

I've been using 89 but wanted to see if I could just start using the 87 from the corner gas station, as it's like .70 cheaper per gallon.

Is there a higher compression ration in an EFI engine than a carbed engine? I've always had carbed engines and always used 87 octane in them, so I'm new to EFI even though EFI isn't new.



Thanks.

 

[dingbat]

Re: 87 Octane in a EFI Merc?

What does the manual tell you to use?

 

[444]

Re: 87 Octane in a EFI Merc?

I've never run 87 in my carbed merc 175 and I never will. Higher octane is more detonation resistant which is a good thing in a finicky oil burning 2-stroke.

 

[JB]

Re: 87 Octane in a EFI Merc?

I've never run 87 in my carbed merc 175 and I never will. Higher octane is more detonation resistant which is a good thing in a finicky oil burning 2-stroke.

Mythology. Read your manual and ignore shadetree "wisdom". It is mainly attempts to sound wise.