[robwiseman]

I know the book says regular is fine...but is it a good idea to use a higher grade? Keep the engine clean and run smoother? Maybe better MGP? :?:

 

[Resist]

Not always. If the engine wasn't designed for the higher octane you may actually be hurting the engine, and lowering your gas mileage. With the pumps as high as they are right now, why even think about paying for premium?

 

[Insightful Trekker]

I know the book says regular is fine...but is it a good idea to use a higher grade? Keep the engine clean and run smoother? Maybe better MGP? :?:

The Insight like many other cars has an engine "knock" sensor. This sensor allows the ECM to fine tune the engine for best performance based on how the grade, or blend of grades of gasoline in the tank is burning. Basically it adjusts the ignition timing.

In theory this has the ability to increase the MPG of the vehicle. However, chemically, higher grades of fuel can also be shown to contain less heat. In most cases the anti-knock compounds added dilute the fuel and themselves contain less heat energy. Remember its the fuels ability to heat the air in the combustion chamber that generates the mechanical energy.

So the overall balance of increased performance from more advanced timing vs. lower available heat energy often times translates to little or no MPG improvement on the road. But most often the increased cost of premium vs. regular _never_ offsets any savings from increased MPG.

Finally in regard to increased detergents in premium blends there was a real world problem about 15 years ago with a reformulation of gasoline and increases in engine deposits. Your only protection back then was using premium fuel. However, the problem was so widespread and the most severe forms caused auto manufacturers so much trouble that the big guys duked it out and now even the regular grades of any major brand of fuel has sufficient additives to eliminate serious deposit buildups for virtually all conditions.

HTH

John K. Bullock
Knoxville, TN

aka. Insightful Trekker in cyberspace.

 

[Aaron Cake]

Remember that higher octane fuels burn slower and are harder to lightoff. All modern cars have a knock sensor, which lets them run on the lowest octane possible. Higher octane fuels are still available for olders cars, turbocharged/supercharged cars, and vehicles with very high compression engines. "Regular" fuel should be used in the Insight.

 

[Tim Maddux]

More discussion of this topic here:
http://www.insightcentral.net/forum/viewtopic.php?t=9

I tested premium and regular unleadeds on 10 tanks (5 of each) alternating and could not detect a difference in either performance or mileage.

Others tested this (discussed in the Yahoo! forums) with a dynamometer and OBD-II setup and found no difference in power with premium IIRC.

Use regular.

 

[Rick]

Doesn't the Honda Service manual say premium though for best preformance?

 

[Rick Reece]

Fuel

Pat Michaels did a comprehensive test on the same day to keep weather differences at a min, of 5 test runs over a controlled course with different grades of gas. He found that the higher grades give better mpg performance. I havn't done the controlled test that Pat has but can see a significant difference on my Interstate cruising. I use Exxon premium which seams to give me better mpg values (about 4-5 mpg). Depending on the price difference in grades depends on which grade is more economical but pollution wise premium would seam to be best. There are also differences in the gas blends (summer vs winter and big city vs country). My experience shows summer grades outside the big cities tend to give the best results). Have fun, Rick