When I bought my RL no one told me I had to use 91 octane or higher. Its my first high performance car and I didn't know any better. Shame on me yes haha. But my question is... Because the lower than recommended octane fuel will ignite before its where it needs to be inside the engine, i know it decreases fuel economy, but can this affect engine temperature at all? Would my car be running hotter than it should? Thus drawing more coolant than normal? See, my car has been going through coolant like a mother effer and even the dealer can't tell me where its going. If I put the 91 octane in it, and fill the coolant up again should this solve my problem? The dealer ran compression tests, leak down tests, all kinds of tests to see where the coolant is going and they said that its not ending up anywhere it shouldn't be (oil, tranny, head gaskets). All answers to my problem are greatly appreciated as well as any other input. Thanks guys.