Fuel Octane...what are you using?

Ever seen flames coming from the exhaust of race cars? What does this mean? It's too low octane for the applications or the revs are still high on deceleration it did not burn fast enough so the unused fuel burned off in the exhaust waste of fuel and power if it does not burn it does you no good. This becomes an issue with a engine turning maybe 7 grand. Not in an engine that will never see 6 grand. The heat value of 87 and 91 are pretty much the same. All modern engine have knock sensors so if you race yes spend the money on 91 other wise your wasting money. What the knocking at your door comes from the flame front moving slower than the speed of sound. You all can do what you want and I'm sure your engine will grin from ear to ear maybe even send you a nice note when you spend the extra bucks to make it "happy". Toyota says 87 or greater meaning don't burn 81.

 

Mine has no evap pump I can easily put in 2 gals after the pump clicks off. The expansion of cold gas is about 1.5% from ground to summer heat in the winter time that's not even and issue and with in my 8 miles drive home from the gas station what may have expanded is all ready burnt. Mind you I have only driven this truck 120,000 trouble free miles so who knows what will happen at 300K. Drive more worry less.

 

engine was designed for 87 octane, so anything else is wasting your money. Plain and simple

 

I run 87 both with E10 and without. The tanks without E10 tend to provide slightly better mileage, but I haven't kept stringent enough records to quantify that, so it could be in my head. The RPMs under acceleration and the sound/vibration of the engine (gets buzzy and loud around 2000 rpm) didn't appear to change with either version. Quality of gas does seem to make difference, say Shell versus bottom dollar grocery store gas.

I have run one tank of premium w/ no ethanol (91 I think), and after the engine worked out its confusion in the first 20-30 miles on running on something different (which was pronounced, the shifting was very confused), it started to run noticeably quieter/smoother and at lower RPMs under the same rate of acceleration. I wasn't expecting much of a change, the only reason I decided to go premium was because gas has become so cheap such that premium was the same price I was paying for regular a year earlier, so I figured what the hell. Once the engine figured out the new feed stock and adjusted fuel trims accordingly, I basically had to mash the pedal to get the RPMs above 2000, whereas before, RPMs would go over 2000 even under mild acceleration when going up hill. The increase in torque was very evident, although on paper might have been minor.

Before the tank of premium, the noise and vibration of the engine when it got into the 2000 rpm range sounded so rough, that I ended up buying a exhaust pipe damper made for a Highlander and bolting it onto my exhaust pipe just after it does the dip under the transfer case. The damper seemed to help reduce the buzziness of the engine a bit, but I couldn't be sure it wasn't all in my head. However, with the tank of premium, the sound of the engine was night and day different, no question. It sort of reminded me of driving a luxury car, the engine just purred, even in the 2000 rpm range, and the truck was just more enjoyable to drive.

However, that all said, I can't say the mileage was noticeably higher during that tank. It seemed about the same. On the highway, I can't say for sure if it held gear longer going up hills in cruise control than before either, but the engine did seem to be less noisy.

While the feel was nice, I can't say it was that much better, that it would be worth springing for the premium on the regular basis. I'll likely stick with 87, without ethanol if I can find it, and be happy. Maybe Ill run premium on road trips to cut down on cab noise though.

 

93 here or 91 if I ever see it.

 

Butt dino's and perception are notoriously inaccurate.

 

Ethanol is close alcohol in octane rating both are around 110

 

^^ Gen 2, 87 Octane since birth, 302,000 miles and going strong. If it ain't broke, don't mess with it is my advice!

 

I run straight bio diesel in mine. I like that it smells like French fries and Popeyes chicken.

 

If the difference is $.40 a gallon, then why fill up with the expensive stuff when you could add a bottle of octane booster for less?

 

The guy your talking to does have a pump. As do I. In fact, most people reading this do as well. You know why? Because this is the third gen section where we have pumps.

Telling a guy he is filling his truck up wrong when you don't even have the same truck is such a second gen thing to do.

 

Come to Oregon, you'll never top off again (since you can't pump your own). One click and done.

 

Found a local dealer selling 93 octane non-ethanol gas for boats. Been using it and mileage has gone to 22 mpg/gal. Will continue to buy it @ 2.95/gal.

 

My 06 4L is happy with 87 so I run it. Personally I prefer to run Tier 1 brands which works well as Costco is both Tier 1 and the cheapest gas locally.

https://www.eia.gov/tools/faqs/faq.php?id=27&t=10

The energy content of ethanol is about 33% less than pure gasoline. The impact of fuel ethanol on vehicle fuel economy varies depending on the amount of denaturant that is added to the ethanol. The energy content of denaturant is about equal to the energy content of pure gasoline. In general, vehicle fuel economy may decrease by about 3% when using E10 relative to gasoline that does not contain fuel ethanol.

 

I would normally agree with you, but the difference was night and day on a item (rpm, engine noise and vibration at around 2000 rpm, the rpm where the exhaust system goes into resonance) I had been keeping a very close eye/ear on up to the point I had happen to try premium for the first time.

There isn't any other variable I can account for. It is possible that the shock to the ECU system was enough to cause it to relearn, and it isn't so much the gas as my ECU had gone down the wrong path in life, and this tank of gas was enough to cause it to sober up and change its ways. I did go back to regular after that tank and the engine still seems to run better than before, but not quite as good as with premium. I'm at 8k on mileage so you would think the engine has finally figured things out. It's all a mystery.

 

Agreed. I rather see some real detailed data than what someone "feels" they get.

 

wny not extra virgin olive oil ......or better still, extra, extra virgin live oil

 

what brand of 87 did you try that gave bad results

 

Costco, Shell, Speedway, Meijer, Kroger, various others.

 

i use Costco when i can get it for local driving and trips when i can get it......if i can't i use Shell 87.....i notice no difference except wallet gets lighter with shell......mileage is great on trips (24-27) and 21-23 locally.....something must be wrong.....maybe bad ECU