So premium is a waste with a low compression engine like this 307.Chevron said:(http://www.chevron.com/prodserv/fuels/gas_qanda/api_octane.shtml)
In most vehicles no benefit is gained from using gasoline that has a higher octane number than is needed to prevent knock. However, in some vehicles equipped with a knock sensor (an electronic device installed in many modern engines that allows the engine management system to detect and reduce knock), a higher octane gasoline may improve performance slightly.
eeMogul345 said:The chemistry of gasoline says you should use the lowest octane possible w/o running into detonation. The higher the octane, the slower the gasoline burns in the combustion chamber. It's also harder to ignite higher octane fuel.
So if you don't get any detonation with 87, go with it. You'll be wasting money with premium.