Can mid-grade gas be used in a supercharged 3.8?

[Reatta Man]

I'm looking at a car with the supercharged 3.8 engine.

I'd like to hear from some GM or Buick techs or service writers or owners who know if you can use mid-grade unleaded in the 3.8 SC engine. Specifically, will it damage the pistons, valves or supercharger with preignition, or does the ECM adjust when it hears the preignition?

Have any owners gone to mid-grade unleaded for an extended period? If so, what kind of experience did you have? Loss of power? Poor drivability? Or did you not notice much difference at all? Has anyone gone so far as to run regular unleaded in a 3.8 SC engine for a while?

GM only used the SC engine in their top-tier cars, so I would like to buy the car. I've owned two Buicks with this engine before, but that was in the days of $1.25 for a gallon of 92 or 93 octane premium.

Any advice would be appreciated.

Joe

[NTX5467]

The knock sensor will take care of lower octane fuels. When something more than 87 R+M/2 posted octane is spec'd, it means the system is calibrated to produce more power with the higher octane fuel, but the detonation sensor will keep detonation from happening. There's an excellent commentary on this very subject on one of the performance websites (plus tips on how to successfully drag race GM fwd cars and how to get them to run faster than they normally would!). Seems like it was at www.zzperformance.com? There's lots of information on how and when and how much the spark is retarded when just one detonation rattle is sensed by the sensor. Really neat stuff!

Enjoy!

NTX5467

[brad54]

I go back and forth with my wife about this all the time--I only run Premium in our cars (93 Chrysler Concord and 2001 Dodge Dakota). The Concord has 140,000 miles, doesn't burn a drop of oil, gets great gas mileage and runs like a champ. And it's been far from pampered.

I know for a fact that the Dakota runs better and gets better mileage with the Premium.

Now, the difference in Premium is what, 10-12 cents a gallon more than mid-grade? Say it's 10 cents more per gallon. With a 20 gallon tank and a total fill-up, you're dropping a whopping Two Dollars more than running cheaper gas.

($1.50 in her 15-gallon tank). That extra couple bucks just kills her, which just kills me.

Computer controlled or not, the cars seem to perform better with 91/93 octane, so that's what I burn. At a max of $2.00 a tank more, I think it's worth it.

-Brad