Just bought a used Corolla xrs... Fuel door says USE PREMIUM FUEL ONLY... Ture or not?

The Corolla XRS uses a high-performance motor that needs premium fuel. Sorry, you gotta pay the money for it.

Although it is recommended by the manufacturer to use premium, it is not absolutely necessary. Your engine won't be damaged or anything if you use regular. The only thing you'll lose is performance, because the XRS has a strong motor, but with gas prices these days I think that is a sacrifice you're willing to make?

If the manufacture recommends premium it is for a reason. It's not a selling point for them, they aren't going to put the sticker on there because the sticker looks pretty. Generally speaking they require for one or both of two main reasons.... 1) High compression 2) An advanced timing map. Use of low octane fuels in either case can lead to pinging or pre-detonation, which contrary to what Sang says can eventually damage the engine regardless of how strong it is. On the plus side you likely won't do any serious damage since in most places the octane rating posted is a minimum and is generally higher than stated... Additionally there are safety coefficients in the equations used to determine fuel, and the vehicle will likely only pre-detonate if it is out of tune slightly. And as for Sangs second comment about performance... a little secret if the car can run on low octane it'll generally run better on it. This is due to the fact that low octane has a higher caloric value and contains more energy. It is however less stable so increase compression and optimizing timing will cause it to burn irregularly and becomes less effective in a more efficient motor. A bit of a paradox really... But basically if you have a cruddy car you get to get cruddy gas...if you got a nice car you have to get nice gas... As for why your car wants premium... I would guess the compression in the engine... which is I believe 11.5:1... This is incredibly high hence why you suffer both a performance and potentially a reliability decrease with a lower octane fuel.

Thanks All

On the gauge cluster of my Integra GS-R, it says that it requires "premium unleaded fuel only." However, looking at the manual says that if you live in an area where no high-octane fuel is available, put in the highest octane you can find. My car has a knock sensor which will back off on the timing when it senses a lower octane, but I've never put the car through that. I, by NO means recommend cheaping out, so just do what the car tells you to. Your gas mileage would also drop down if you put a lower octane for it. If you can afford the car, put the right gas in it.