I walked in to service my S2000 at the dealership and before servicing the car a tech asked me whether I use premium fuel. I told him no. He was aghast and told me that this is bad for the engine and significantly reduces performance. Is this true? If so, how much.

 

high compression equals premium fuel because of the tendency for lower grade fuels to cause knock, thus prematurely killing your engine. at higher elevations it's less likely to happen (i believe) so you can get away with running a mid grade in some vehicles. i'm sure someone else can get a bit more technical on this than i can or i'm almost positive you could search around a bit and find some write ups on what different grades of fuel mean exactly and why you should/shouldnt be running them.

 

Oh my, I am aghast too. Just use premium.

 

Use premium... its designed to use premium for a reason. Will it do any harm? I honestly doubt it... your ECU is smarter than that.

 

Your tech is correct.

Only use 91 octane fuel or higher in the S2000.

 

Uh it even says so on the inside of the gas lid label.

 

I only use 93 octane in mine.

 

OPTIMAX only for me..

 

i've always used regular 87. 76k miles later and no problems.

 

Come on...its a specialty sports car, at least give it some nice gas... If this were some run of the mill Honda or an "average" car, then yea giving it "average" gas would be fine. But it isn't your average car... Just spend the extra few dollars (if that) per fill up and get Premium...

Yea running 87 or whatever might not have any adverse affects, but it just raises the risk... Why risk having to fix your complete motor or replace some expensive parts when you can just run higher octane and just rest easy...