MSN has posted an article about little gas station secrets worth checking out.

I'll add to it the following - what they won't tell you:

1. My gas may be clogging your engine. Gas stations have to change their tanks every few years to clear out the dirty deposits. If you happen to be filling up around the time I have to change, you're getting those deposits into your engine.

2. Our gas is all the same, just how we market it. My super unleaded octane 92 is the same as the gas station across the street's super unleaded octane 92.

3. Your car doesn't need super unleaded to run, but we thank you for purchasing it. All cars are required by law within the USA to run on 87 octane without exception. Older cars may benefit from higher octane if they start to ping, and only new cars that are designed for higher octanes can benefit from it.

4. We provide you with squeegees and window detergent. But you should check to see how dirty it is before you use it, as it may do more harm than good.

5. The absolute worst times to fill up is right when my tank is getting filled up by a tanker, or when the tank is getting empty. All those deposits that have settled to the bottom are now swarming throughout the tank of gas. As the tank approaches empty, the deposit concentration gets higher = dirtier gas.