Super Unleaded or not?

[Law_kenuk]

Hi

I live in England but my sister lives in LA!

She has just bought a 2002 C class Merc (V6, 2.4 auto I think) and was told to run it on super unleaded (or whatever you guys call the premium unleaded rating?).

In the UK most cars will run on either grade of unleaded although performance may be effected. Is the same true in the states?

Thanks

Liam

[Mustang Baz]

Liam - see this; http://en.wikipedia.org/wiki/Octane_rating

US (California at least) Octane ratings from memory were/are 87, 89 and 91; put simply, three gradings of unleaded with 91 being the closest approximation to the UK Super-unleaded option although not necessarily like-for-like.

[Steve_M]

If a car is capable of running on the lowest octane fuel (regular) then running on higher octane pump fuel will increase fuel efficiency and be a benefit to the car.
On the other hand if a car is only capable off running on the highest octane fuel (premium) then running lesser octane pump fuel will have adverse effects.
I would think The Mercedes should be able to run on the intermediate octane fuel but not regular, but the drivers handbook should tell you.