Random Fuel Testing

[mar1]

for the last month, i have been doing some testing on the pathfinder distance to empty with different fuel types and slower/faster driving.

i have a daily trip on 93 miles to work, and the speed limit is 87 mph.
on 92, 95, and 98 Octane, honestly i felt no difference in terms of speed and acceleration. (all driving was done with no A/C)

cruising at 87 mph with the minimal change in speed, all three types were very near in figures.

92 octane suffered the least distance at 320 miles (i only filled once with 92)
with 95 and 98, i was getting distances between 330 to 350 miles (3 times each)

i noticed the engine stayed at 2.5-3 rpm while cruising at 87 mph. i dropped the speed to 65-70 mph, and noticed a notable change. the rpm dropped to 2-2.5, and i managed to squeeze 400 miles on one tank with 95 octane.

just wondering if we had a sixth gear, if we would have had better fuel economy for long distance drives.

[deermjd]

That's some interesting testing you've done. I did some experimenting of my own a while back. I compared regular octane (87) with premium (93) using 3 tanks of each. I also couldn't tell any difference in power or fuel economy. So I just stick with regular for everyday driving.

Perhaps having a taller sixth gear could help out on those long highway drives cruising at 80 or higher but at those speeds you're really fighting against wind resistance so the transmission may tend to downshift quite a bit.

Just out of curiosity, what mpg are you getting while driving at 87 mph?

[disallow]

No A/C? What are ya nuts?

Its been a warm March here in Canada, and I've been using A/C the whole time!

[mar1]

Just out of curiosity, what mpg are you getting while driving at 87 mph?

330-350 miles on a full tank (21.1 gallons)
so 15.5 - 16.5 mpg


Terry, i'm in Dubai. Temps here this time of year are an awesome 70-78

[volvite]

70-78 is nice compared to what you will have in a few months.

[FLiPMaRC]

I was so confused when you posted 92 / 95 / 98 octanes Then I saw your location. Are you saying the lowest octane in Dubai is 92???

[disallow]

From Wikipedia under Octane Rating, explains the difference in the Octane Ratings between Canada/US and the rest of the world:

Research Octane Number (RON)

The most common type of octane rating worldwide is the Research Octane Number (RON). RON is determined by running the fuel in a test engine with a variable compression ratio under controlled conditions, and comparing the results with those for mixtures of iso-octane and n-heptane.

Anti-Knock Index (AKI)

In most countries, including Australia and all of those in Europe, the "headline" octane rating shown on the pump is the RON, but in Canada, the United States and some other countries, like Brazil, the headline number is the average of the RON and the MON, called the Anti-Knock Index (AKI, and often written on pumps as (R+M)/2). It may also sometimes be called the Pump Octane Number (PON).

Difference between RON and AKI

Because of the 8 to 10 point difference noted above, the octane rating shown in Canada and the United States is 4 to 5 points lower than the rating shown elsewhere in the world for the same fuel. See the table in the following section for a comparison.

[FLiPMaRC]

Thanks for the info Terry. So 92 RON in Dubai is the same as 87 AKI for us in N.America I use 89 AKI (95 RON) for all my vehicles.