"Mid-grade" Gasoline Actively Blended to 89 Octane as You Pump It?

[LoneRanger]

https://www.quora.com/How-do-gas-st...tore-various-octane-gasolines-separately

The first answer in the linked Quora question seems to have credibility. I was afraid 89 mid grade gasoline sitting in it's own storage tank would get stale due to not many buyers of mid grade. But this info says that stations have only two storage tanks one for 87 regular and one for premium 91/92/93, and that when demand is made at pump for 89, a blend process is commenced that draws from both the 87 storage tank and the premium one and outputs 89.

Now, I have a question about this. I would think that the blend mechanism, if this is truly how it works, would need some periodic calibration to ensure that it reliably blends to 89 octane upon demand each time a customer selects mid grade.

Can anyone confirm this info about 89 being actively blended, i.e. created, upon demand when pumped? As long as the regular and premium stocks are up to snuff I suppose this works okay and what comes out of the pump actually tests at 89 ...

 

[Donald]

I asked a driver of a tanker who was delivering gas to a station. He was only delivering regular and premium. They blended the mid grade. But he also said it was not always like this and not all stations do this. Go over and look at the covers on their fill caps.

 

[Hall]

Originally Posted by Donald
Go over and look at the covers on their fill caps.
That's probably a pretty good indicator but not 100%. They might have a cover/cap for mid-grade but it's no longer used.

A quick Google search shows lots of indications that it's likely true that there is no mid-grade fuel at many stations and it's blended like mentioned. If this blending is true and common, that has to make mid-grade fuel more expensive just based on volume sales too. This clearly isn't passed on to customers though based on the prices we see.

 

[PimTac]

I would think that calibration checks would fall under the State Weights and Measures dept.

 

[bdcardinal]

It is my understanding it is blended as you pump. I have only bought premium for the last ~12 years but that is my understanding about 89. Here we have 87, 89, and 91 so it is a straight 50/50 mix.

 

[MNgopher]

Completely depends on how the gas station is setup. A big chunk of stations here keep the midgrade separate.

Example: One large retailer here used to be 87 Octane E10 Regular, 89 Octane E10 Mid Grade, and 91 Octane E0 Premium. One physically could not blend the premium E0 and Regular E10 and end up with an E10 Mid-grade.

More recently, the same retailer now has: 87 Octane E10 Regular, 88 Octane E15 Super 88, and 91 Octane E0 Premium. Again, one can't blend regular and premium to get the midgrade. It is stored separately in its own tank...

 

[Hall]

Originally Posted by MNgopher
Example: One large retailer here used to be 87 Octane E10 Regular, 89 Octane E10 Mid Grade, and 91 Octane E0 Premium. One physically could not blend the premium E0 and Regular E10 and end up with an E10 Mid-grade.
They don't need to end up with E10, they just can't exceed 10% and they won't. Is it closer to E5 ? Probably but it's safer for them to call it E10. The 87 octane might only be E4 or E9 or whatever, again, as long as it doesn't exceed 10%.

 

[Win]

At every station I have owned, it is blended at the pump, but I'm sure a local pipeline terminal can blend it and sell it as 89AKI, plus or minus ethanol, or whatever AKI the customer wants.

Land, tanks, and lines are expensive. Pumps are also quite expensive, but are cheap by comparison. Personally, I can't imagine someone wanting to waste land and money on a mid grade tank, but you could certainly do that if you wanted. In my experience, there is little demand for 91AKI or better, much less the intermediate blends.

I was at one of my stations once, and saw one of the state guys pulling pump fuel to lab test for octane. I don't know how often they do it, and if they were checking the blends, or just the end point grades. In my entire lifetime, I've never been notified that a grade failed a lab test.

I would worry more about the honesty, or lack thereof, of the station operator, than the mechanical process of blending. It's not rocket science.

 

[Win]

Originally Posted by PimTac
I would think that calibration checks would fall under the State Weights and Measures dept.


My state, anyway, no longer does calibration checks - pump ( volume ) calibration and tank / line integrity are certified by private contractors

 

[Donald]

Originally Posted by PimTac
I would think that calibration checks would fall under the State Weights and Measures dept.


The state only measures the dispenser that it puts out am exact gallon of gas. They are not measuring octane.

 

[Win]

Originally Posted by LoneRanger
... I was afraid 89 mid grade gasoline sitting in it's own storage tank would get stale ...


Another thing I wouldn't worry much about. I had about 1500 gallons of 87 AKI in a UST for my own personal / family use; took well over a year to use most of it up. A lab might have detected some degradation. My cars didn't care.

 

[beanoil]

I cannot think of a station around me with a midgrade tank.
All are Regular, Premium and Diesel. The pump does the work.
Our Premium is 93, so it's better to go manually at the pump for me with half Regular and half Premium.

 

[MNgopher]

Originally Posted by hallstevenson
Originally Posted by MNgopher
Example: One large retailer here used to be 87 Octane E10 Regular, 89 Octane E10 Mid Grade, and 91 Octane E0 Premium. One physically could not blend the premium E0 and Regular E10 and end up with an E10 Mid-grade.
They don't need to end up with E10, they just can't exceed 10% and they won't. Is it closer to E5 ? Probably but it's safer for them to call it E10. The 87 octane might only be E4 or E9 or whatever, again, as long as it doesn't exceed 10%.


Maybe in your state - Minnesota state law requires all gas sold to be E10 except premium non oxy. Blending as you propose does not comply with the law here. (Minnesota State Law defines E10 as between 9.2 and 10.0 percent) (See Minnesota State Statute 239.791)

 

[Hall]

Oh, I figured the law would more specify the max allowable amount. I guess the farm lobby helped write that MN law !

 

[y_p_w]

Originally Posted by Donald
I asked a driver of a tanker who was delivering gas to a station. He was only delivering regular and premium. They blended the mid grade. But he also said it was not always like this and not all stations do this. Go over and look at the covers on their fill caps.

I asked a delivery driver once, and he said that station received a separate delivery of 89. I saw two trailers, but he showed me the seam that separated the two compartments in one trailer. As for blending, that's up to the station as others stated. Blending is pretty linear with AKI octane rating, and if there's a little bit of extra over the requirement, that shouldn't be a problem. Wayne invented the blending pump, and apparently they can even take deliveries of denatured ethanol and blend that in at the pump.

Originally Posted by Donald
Originally Posted by PimTac
I would think that calibration checks would fall under the State Weights and Measures dept.


The state only measures the dispenser that it puts out am exact gallon of gas. They are not measuring octane.


In California, weights and measures is a function of each county agricultural department's weights and measures division. There's a separate inspection sticker on every grade of fuel, even if it's just one pump handle. San Francisco may be the exception where it's part of their public health department, even though they do have an agricultural department that's part of their public health department.

As for measuring octane, at least here the state has a mobile lab and can randomly audit any refinery, distribution terminal, or gas station.

https://ww3.arb.ca.gov/enf/fuels/fuels.htm
https://ww3.arb.ca.gov/enf/fuels/inspections.htm

It doesn't say anything specific about octane rating, but it was my understanding that the state's mobile fuel lab contains a standard rig to verify that.

 

[SevenBizzos]

Blended. 2:1 87:93 gets you 89.

 

[benjy]

the question of how much of the last customers grade you get when selecting another grade, interesting post for sure!

 

[Linctex]

What's with the price difference???

I might have to swipe the card twice, but I can blend my own 89 a bit cheaper than pushing the 89 button.

 

[PandaBear]

That'll be kind of expensive sending a separate tank for each grade, even if you can keep the tanker full on everything and have them arrive at the same time. Inventory would cost money both in interest (or opportunity cost) and risk (of price fluctuation).

Unless refinery can save money making dedicate 89 octane rather than separate 91 / 87 and then blend them at the pump.

 

[skyactiv]

The few times I got mid-grade for whatever, I noticed/heard the pump clicking in an odd manor. Listen to the pump if you happen to get mid-grade.
There are a few stations that sell 92 octane and obtain it it by blending 93 octane and a small amount of 87 octane, just to make a tiny bit more money.