Gasoline

[silberma]

Folks,
As you may know modern engines have knock sensors that retard ignition timing when the car burns gas with lower octane than it is designed for to prevent engine damage. Does anyone have experience with regular or mid grade gas on a Q70 with a 3.7 liter engine?

[Debonair]

Generally you are OK with lower octane gas. You can just expect lower performance and fuel economy too. On my 5.6L M I ran half a tank or 89 octane due to the 91 button on the pump being broken and me needed to get where ever it was I was going. No issues. Filled it up the rest of the way once it was convenient, a day or two later.

From the UM:

FUEL RECOMMENDATION
Use unleaded premium gasoline with an octane rating of at least 91 AKI (Anti-Knock Index) number (Research octane number 96). If premium gasoline is not available, unleaded regular gasoline with an octane rating of 87 AKI number (Research octane number 91) may be temporarily used, but only under the following precautions:

• ● Have the fuel tank filled only partially with unleaded regular gasoline, and fill up with unleaded premium gasoline as soon as possible.
  ● Avoid full throttle driving and abrupt acceleration. However, for maximum vehicle performance, the use of unleaded premium gasoline is recommended.

CAUTION

• ● Using a fuel other than that specified could adversely affect the emission control system, and may also affect warranty coverage.
  ● Under no circumstances should a leaded gasoline be used, because this will damage the three-way catalyst. *DUH
  ● Do not use E-85 fuel in your vehicle. Your vehicle is not designed to run on E-85 fuel. Using E-85 fuel can damage the fuel system components and is not covered. *DUH

* The "DUH" has been added for emphasis

[Altered]

Real world experience: The 3.7L pings on regular. I used regular in my M before to see how it responded, it knocked on initial take off and ran a little sluggish (like lethargic performance when downshifted). I tried mid grade on the following fill up and it was no better. Nothing but Premium is good for this car in my experience. I suppose you can crawl around on 87 if need be, but to drive the car normally I wouldn't do it.

[stm37s]

I have only used use premium gas in my M, never really thought about using any other type. This is some good info Debonair, thanks.