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![FordMan](themes/aaAle/images/interface/profile-pic-placeholder.47cf740a.png)
Please explain to a non mechanical person about those petrol numbers and is there any way of knowing which is right for which cars??
![jbiddle](themes/aaAle/images/interface/profile-pic-placeholder.47cf740a.png)
Refer to link provided on a similiar Q&A on this subject.
http://www.aa.co.nz/motoring/ask-jack-forum/fuel-running-costs/show/1638/
If your engine has a compression ration of around 10:1 then the lower 91 grade octane should be fine.