Premium grade gas for Mazda CX7

Andy K wrote in news: snipped-for-privacy@googlegroups.com:

As long as your doing normal driving the 89 will be fine, If you like to feel the floor under your accel foot, then not so much. KB

Your best bet is to try it and see. A higher octane number will generally be more resistant to engine knock and allow a more advanced timing for the engine spark plugs. A lower octane number may reduce power in an engine by reducing spark advance. OTOH, if you drive with a light foot on the pedal, you might not notice any difference in power at all between the grades. OTOH, if you hear any engine knock, go to a higher octane gas.

Yes, you can use it without any problems IF the owners manual says you can. Even if the owners manual doesn't say you can you can still almost certainly use it without problems because all modern cars have knock sensors to adjust the timing to handle any normally available grade of gas. I forget the details but IIRC if the manufacturer rates the power while using high octane then they have to rate the fuel economy on high octane too. So if higher octane gives them enough extra hp that they want to be able to advertise that higher hp they are stuck with what will probably be lower gas mileage in their ads. And also stuck with the lower gas mileage when calculating their CAFE. So for cars that they sell jillions of they are likely to use low octane and give up the extra 10 hp. But for a high performance car they only sell a relatively small number of they may be willing to bite the gas mileage bullet and specify high octane so they can get that last bit of hp that they will then advertise.

So use the lowest octane fuel you care to as long as you don't hear pinging or experience knocking (it's extremely unlikely you would experience either, the knock sensors are so sensitive they hear any pinging and adjust for it way before it's loud enough for you to hear. The last car I had that would ping on low octane was a 1986 model with the very early knock sensor. It took about a second for the computer to adjust the timing and stop the pinging/knocking. Everything I've had since then adjust so fast I've never heard a thing.

Why don't you try some different grades and report back what happened and whether you could tell a difference in performance.

There has been no decrease in performance. I am easy on the gas pedal.

I will report back on my m.p.g. results of mid grade vs. Premium grade.

I got 19 m.p.g. with regular gas. (combination of city and hwy driving)

Andy

I'm trying regular instead of premium in my Passat 1.8T. It feels a bit ponderous. I'm not enjoying it too much. It might not be worth the couple of bucks I save.