Started using Premium gas for my 2006 SR5 Sport, 160K miles

Well here's my $.02CAD.
I add 1ltr diesel to 20ltr gas on fillups. Doing it for a few years now, in my Matrix, and old Tacoma. Just did a couple tankfuls on this Taco, but I'm going to go just straight gas for a bit. ( just to see if there's any difference in this Taco.)
Never really noticed better mileage, or power, but didn't measure anything scientifically, so to speak.
Adding diesel is supposed to be " poor man's octane boost".
If you decide to do this, do so at your own risk, of course. Add more, or less diesel, I just kinda guessed it.
Do add the diesel first, as its lighter than gas and will mix as it floats, I've been told.
Don't do it in the winter.
Wadda ya think, eh?

 

Not sure if serious or just a troll. Adding diesel, which has an equivalent octane rating of something like 12-15 using the "(R+M)/2" method (which all street legal "pump gas" fuel in USA is calculated by) would lower the octane rating, technically. Putting one gallon of diesel fuel per 20 gallon fill-up, the rest with 87, would bring the avg octane rating of your tank of gas down to 83.25, not to mention the soot and uncombusted diesel would be hard on the cat since the AFR would be way too rich for good combustion of diesel fuel in a relative low compression environment. Typical diesel engines run from 16:1ish to like 80:1 AFR and compression ratios of around 20:1. That said, diesel flashpoint temp is well over that of gasoline so I guess it could help with pre ignition/knock resistance if it were to blend well with gasoline. I don't think it mixes, though. In all of my years of wrenching on aircraft I can't remember having both types drained into one container to see if they mix or separate. I know the densities are quite different.

 

I splurge once in a while....run 88 instead of 85......

The real question is.......

Do you run ethanol free fuel if you see it at the pump ?

 

You have it pretty well figured out!

The cheapest gas here in the San Diego north county area that I found last month was at Costco, $2.29/ gal.

 

My theroy is that during the Great Recession when regular gas prices were over four bucks a gallon, Toyota feared suggesting the use of premium fuel might scare away customers, so they stopped suggesting that. At any rate, I have experimented with 87 octane and have found 91 does improve power somewhat. Absolutely zero improvement in mileage. I run only 91 octane or above since that experiment. Heres the complete documents I found supporting my hypothesis. I think I found them on Toyotas website.

 

I wouldn't be surprised about that marketing change.

If it improved torque it improved economy. You can't have one without the other. Either it makes more power with the same amount of fuel or it uses less fuel at the power output as before. I suppose it could not make more power at low load/cruise load but that would just be unfortunate tuning on the ECU.

 

Toyota used to recommend (not require) 91+ octane in the old MZ V6s. They would perform fine on 87 but picked up a bit of performance with a higher octane. Even said as much in the manual. But telling the average Camry owner or soccer mom with a Sienna that they need to use the expensive stuff proved futile. When the GR series replaced the MZ engines, Toyota didn't even bother talking about it anymore....except briefly in the 1GR powered FJ for a couple of model years. But even that fell out of favor with the buying public...especially during the Great Recession

 

I just pulled this from the Toyota website. Page 270 of the 2006 Owners Manual. Missing from '07 and above manuals.

 

Would be interesting to see the fueling and timing tables from an 06 and a later model 2nd gen.

 

It certainly would. They might have cracked open the ECU and detuned it, but why would they? Just quit telling people about running premium and leave the ECU alone, considering it runs fine on 87 octane. Deleting one sentence from the Owners Manual is cheaper and easier than redoing the maps on the ECU.

 

Or you live by the pipe line so 91 is .10 more than 87 and your still under $2.50 a gallon

 

GrundleJuice, I'm not trolling. Just going by what a mechanically inclined, worked in a refinery bud told me.
Like I said, I'm going to try running straight gas for the next few tanks, see if my l/100km goes up or not.
Thanks for your input. I'm no chemist, I just try simple shit sometimes if I think I won't hurt anything too much.

 

Back in 89/90 I had a Chevy Cavalier Z24 with the 2.8 V6 and 5 speed. When I ran 87 octane it would average 22 mpg and running 92 or 93 octane it would average 24 mpg (the car would get 31 mpg on highway trips which was not bad for 1989). Since the engine was only rated around 130 hp, I put 92/93 in it most of the time and eventually added a chip and lower temp thermostat. I don't think the gas back then had ethanol so that may make a difference. I think the computer was able to add more timing which results in more hp and mpg. Before computer EFI, we would advance the distributor until the engine would ping and run the highest octane you could find. I think nowadays, the higher octane fuels also have more detergents which should help keep the engine cleaner in theory. My 93 Z28 with a supercharger had to run 93 octane so I never had a comparison on that car. It's a personal preference if you feel it runs better, if it definitely gets better mpg and you don't mind paying the extra (some will be paid back with the better mpg). I haven't tried 92 octane in my 2.7 yet so I've got no comparison on this truck either. I get about 3-4 weeks out of a tank of gas so it wouldn't break the bank for me to switch, and of course I just filled up with 87 today so it won't be any time soon.

 

If you want High octane fuel try E85 , that's 108 octane

 

nevermind the fact that ethanol is low power crap

 

I poured all my wildfire generator fuel into my truck when the threat was gone. It felt better. Way better, but I think that’s because it was non ethanol. Or it could have been because I was happy because my stuff didn’t burn up and EVERYTHING just felt better. Food tasted better, beer colder.

 

I have a buddy who auto-xs his FRS. In addition to some exhaust work he has a flash to run E85 during the race season. I have driven the car on both fuels. Very noticeable difference in the corn juice. Way more kick

 

Not sure how that works since Ethanol has less energy than gasoline.

 

Maybe he's thinking methanol???

 

a proper tune (and fuel system) for E85 will def pull more power out of a motor given the higher octane rating and ability to run more timing BUT you will need to supply a good amount more fuel as stoich for E85 is 9.8:1 vs 14.7:1 for regular gas.

That stated. DO NOT BE STUPID AND PUT E85 IN A TACO. Unless you want to replace all the fuel system components..