LastBoyScout

I have a 1996 Acura TL 2.5L

it has a compression ratio of 9.6:1

The car says premium fuel

I know that people often tout 10:1 or higher being the threshold for using premium fuel, suggesting regular as fine for anything below that

Im wondering if anyone has done the work to find out if using the recommended fuel would benefit me over saving a few dollars a tank.

I have a scangauge so I may just give it a test after this tank.

Question in point: Do our cars get better fuel economy with Premium, Regular, or the same with both?

I did clear the ECU and let it relearn the first time i put regular in and I know that if the fuel was not performing like the engine needs it would retard the timing to compensate thus affecting performance and FE.

TexasHonda

This question has been discussed at great length. If search function works look for these for lot's of opinion, but not a great deal of facts.

I'll give you my facts and subjective info. I have a 97 2.5TL. I monitored (OBDScan) timing w/ both premium and 87 LL and could detect no difference in timing advance at cruise speed on highway. This is where you might expect a difference since knock detector might detect pinging and retard timing. I monitored MPG, both scanned and measured, and could detect no difference. I'm a very easy driver, but acceleration was not affected to my ability to discern.

That was some time ago. I've been using regular for last couple of years w/ no change in performance of vehicle. It gets about 22 mpg around town and 25 mpg on road. It does not have a working lock-up torque converter, or would do a bit better on road, perhaps 27 mpg.

good luck

99AcuraTL99

The difference between regular and unleaded is octane rating. Different engines require different octane ratings so they dont detonate or knock. Try unleaded and if it doenst knock then your fine. it does NOT affect performance or mileage, some people swear to it, but its a myth, thats not true.

LastBoyScout

Hate to knock ya there 99, but im showing a 2.5 mpg increase using premium over regular so far on this tank. I usually get around +/- 26.5MPG if I fillup with the Low Fuel Gauge lights up (around 14 - 14.2 gallons). My scangauge is showing me as having a 29 - 30 MPG average. Im err on the low side and say 2.5 but my scanguage has been calibrated and I use the same gas pump and the slow setting and my fillups are well within a few 100ths of a gallon according to the pump.

Trust me, its not my driving any differently either, all I did was reset the ECU and let it relearn the new fuel.

Only a few test tanks will tell for sure. I will post back in about a week when my tank runs dry.

99AcuraTL99

Gas mileage can fluctuate normally. A vehicle can not tell what type of gas you put it. Tell me how higher octane gives you better gas mileage? It doesnt, all it does it prevent knocking in higher compression engines. There is no way that it decreases the amount of fuel used. You might be acheiveing better gas mileage because you reset your PCM, and it is learning the fuel trims again.

LastBoyScout

Me <--- Not a Petrochemical or Automotive Engineer.

Only think I know is that my IGN number on the Scangauge would fluctuate at a set RPM, TPS, and LOD with regular. With Premium i dont get this, so it would lead me to believe that i was having issues with the regular fuel which was causing the engine timing to be retarded somewhat.

But hey, whatever, like I said, i will post the final number after a few tanks worth of evidence, but i reset the ECU anytime i do engine mods, switch fuel grades, or manage to find fuel without ethanol in it.