Oliver Enterprises

In my area, the VAST majority of the time (~95%) I only have access to 87 octane E15, 89 octane E15, 93 octane E15, 87 octane E0, E85 and diesel fuel. There are a few places with 90 octane E0 at which I fuel up the mighty Scamp. However, the point is, I have very little to no access to 91 octane. Which is what Lexus spec's for the LS.

I was reading about mixing octanes and it is a simple affair, no problems at all. And I also read (don't know the fact of the matter) that some stations that have like 5 different octane choices, they're actually doing the mixing at the pump to achieve those in-between octanes. I've just never cared before.

I wanted to consider this to put a number to the amount of potential savings there is if one were to go through the trouble of mixing octanes. Here's what I found out, prices and savings based on my local prices. My theory was that there would be higher savings with mixing 87 & 93 octane. My costs locally right now are: 93 = $3.279 per gallon. 89 = $3.039 per gallon. 87 = $2.779 per gallon.

There are 2 ways for me to get 91 octane:

• Mix 93 and 87 octane. 2 parts 93 octane to 1 part 87 octane.
  • Let's say you think you'll take on 15 gallons. First pump 10 gallons of 93 octane, then 5 gallons of 87 octane.
  • This mix would cost me (locally): $46.69. Saving $2.50 versus buying 15 gallons of 93 octane.

• Mix 93 and 89 octane. This mix is exactly 50 / 50.
  • The same 15 gallons added to the tank. First pump 7.5 gallons of 93 octane, then 7.5 gallons of 89 octane
  • This mix would cost me (locally): $47.39. Saving $1.80 versus buying 15 gallons of 93 octane.

• Lastly - Just for argument sake, let's say one drove it until the car was running on vapor. Just to get a feel for the maximum savings mixing a tank.
  • The LS tank holds 22.1 gallons. Let's say 22 gallons.
  • First pump 14.67 gallons of 93 octane, then 7.33 gallons of 89 octane
  • This mix would cost me (locally): $68.47. Saving $3.67 versus buying 22 gallons of 93 octane.

I'm not advocating mixing. I just found it interesting because I'd never considered it before. And I found it interesting that to get 91 octane via mixing, in both cases it was a simple mixture (2:1, or 1:1). Which makes me believe that at those stations that offer many different octane leves, that they are indeed mixing 87 and 93 octane.

Would I do this? Probably not. However, I'm so tight with money my butt squeaks when I walk! So it was worth considering.

I probably average 13.5 gallons per fillup. Which would be a $2.25 savings! Hey … that's a couple free bean burritos from Taco Bell!


Jason Oliver

Spudo769

'I probably average 13.5 gallons per fillup. Which would be a $2.25 savings! Hey … that's a couple free bean burritos from Taco Bell! '

Wonder what the octane rating is inside the car after that??!! Lucky for ventilated seats and a pollen filter!

sktn77a

iTrader: (2)

Never heard of this before (?!)

writes123

Here in SoCal, we are stuck with 91 premium gasoline. All E10 for the most part.

Oliver Enterprises

Hey Spudo! Chuckle chuckle. In reality I'm fairly low octane these days as I try to avoid excessive carbs. I haven't had a bean burrito in a couple years probably.

I forgot to mention, I can't remember if locally the gas is E10 or E15. I don't pay attention to it. I would prefer we didn't burn our food, and just go back to E0. My 1972 Scamp would like that too. Then I could go to 93 octane E0 and advance the timing a skosh more. I was reading about Amoco Ultimate the other day, that I used to burn in my racebike. I sure wish we still had that fuel available to us. That was some high quality gasoline.


Jason Oliver

wasjr

I've been told by my buddies that I will squeeze a quarter until the eagle s**ts.

I'm in your situation as to available octane. I put 93 in the LS, but have been known to put 89 in the MDX. I did this yesterday as I was running on fumes. The community that I live and work has the highest gas prices in the area. Yesterday it was 2.95/3.35/3.75. At Sam's Club, a few miles away, 87 is 2.49 and 93 is 2.78.

sha4000

iTrader: (1)

Nice of you to do the math. I've done this lots of times when I have half a tank of 93 I would fill up with 87/89 octane from different station to see what affect it would have on the mpgs and the driving behavior of the vehicle.

Nospinzone

DriverSS

I resemble that .25 remark... don't know if that's a good thing or a bad thing ... Anyway, I'm not gonna pay more for fuel than is necessary when I'm putting 400 miles a week on my Lexus. Notice I didn't say "required"? I have tracked the last 52K+ miles meticulously in my 2007 LS460 and I NEVER, Never EVER, put Premium Fuel in it. No 89 octane, no 93 octane. Not once. I run 87 octane from Shell, Murphys, HEB etc.. Not too picky, just go to places that sell (move) a lot of gas.. Over the life of that 52K I averaged 21.5 mpg, with a best of 24.7. I run 30/70% street/highway. Highway around Austin is run 10-15 miles and stop, run another 15-25 and stop. None of my "Highway" runs are clear sailing. Pretty sure if I did longer trips with "real" open roads I'd inch up to over 25 mpg.

My thinking is the entire Premium Fuel thing is garbage in the States unless your local area is renowned for crappy gas. I believe between the way we calculate Octane, (R+M) / 2, the engine management of the Lexus (and my Mercedes as well) and The Gov't regulatory controls on quality here that any Lexus "Requirement" is hogwash... But if you can make a argument contrary to my real world experience please do.

Oliver Enterprises

DriverSS - I don't think there is a big issue with running 87 octane. However, if you line up your 87 octane fueled LS, against my 93 octane fueled LS at a dragstrip, I'm getting to the finish line first. That's the biggest difference. Is that important to me? Meh, not so much. But to others maybe. I run 93 octane because I don't have access to 91 octane, and 91 octane is what is specified. I know Toyota, and they wouldn't specify higher octane just to make a customer pay more, or for the snootiness factor. There's a legit reason behind it. My belief is that the reason has to do with engine performance. The better the engine performance, the happier the customer will be. The happier the customer is, the more likely they are to buy another Toyota product.

The Toyota leadership are really excellent business men who work with really good engineers.


Jason Oliver

DriverSS

Jaso, if we get into timing, knock sensors etc... there may be something there. I might switch to 93 for 4 or 5 full tanks on the '10 and track them. If the engine makes better power then it will show up in the fuel mileage. IF it doesn't then I'd take you up on that drag race. Honestly, I don't expect it makes a bit of difference here in Texas. I would bring up my point again that gas is very different in other parts of the world and that's what the Lexus 93 only fuel requirement is there for. Mercedes has the same requirement. Someone go putting a Supercharger or running NOS then I can see hunting out the 93 or even better some MS109 for their ride.

Now if it was PURE gas, no ethanol mix, 93 Octane, I'll easily give you that point about better power. The ECM could adjust significantly for that. But stations that sell pure are few and far between. I know of only one here in Austin (Murphys at 620/183) and they just opened it up a month ago.