I like you and you like me, yes?
Sorry but I had to gag you
Unlike the ephebophilic title character of today’s featured record, I did stay in high school – where I not only got all A’s in my high school mathematics classes, but also co-captained the school math team.
Those mad math skills come in very handy when it’s time for me to fill up my car with gas.
You might think choosing where to buy gasoline for your car isn’t that complicated. But you would be wrong!
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Let’s begin at the beginning.
My car takes 89 octane gasoline – often called “plus” or “mid-grade” to distinguish it from regular (87 octane) and premium (93) octane.
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Did you know that if you mix gasolines with different octane levels, the overall octane number in your tank will be an average of the fuels you've mixed? For example, mixing equal amounts of 87 and 93 octane will result in a blend with an octane rating of 90. (That’s because 87 plus 93 equals 180, and 180 divided by two equals 90.)
So one way for me to get the 89 octane gas recommended for my car is to fill my tank with two parts 87 octane regular and one part 93 octane premium – 87 plus 87 plus 93 equals 267, and 267 divided by three equals 89.
Why would I want to go to the trouble of doing two transactions at the gas pump – filling my tank two-thirds full with 87 octane gas first, and then pumping enough 93 octane gas to end up with a full tank of 89 octane – when I could simply fill my tank with 89 octane fuel?
Check the prices for all three grades of gasoline the next time you stop by your local gas station. I’ll bet you dollars to donuts that you’ll find that the price that the price for 89 octane is much closer to the price for 93 octane than it is to 87 octane.
For example, the Shell station nearest 2 or 3 lines world headquarters currently charges $3.01 for regular, $3.81 for mid-grade, and $4.01 for premium.
If the mid-grade at that station was priced in proportion to its octane content, it would be priced at $3.34 instead of $3.81. This means that you can save money by mixing your own mid-grade at the pump.
Say you need 12 gallons of gas. If you fill up with mid-grade at that station, you’d pay $46.72. But if you bought eight gallons of regular and four gallons of premium, you’d pay only $40.12.
By mixing regular and premium in a 2:1 ratio rather than simply filling up from the mid-grade pump, you’d end up with the same amount of 89 octane fuel but you’d spend 14% less!
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How many of you shop at grocery stores that offer discounts on gasoline based on how much you spend on groceries?
In my area, one of the large grocery chains has a deal with Shell. For every $100 you spend at one of that chain’s stores, you save 10¢ a gallon when you buy gas at a local Shell station.
Let’s say you spend $500 on groceries in a month. That means you can save 50¢ a gallon on your next fillup.
But you can only use that discount once. If you buy five gallons, you save $2.50 – but if you wait until you have room in your tank for 15 gallons, you save $7.50. So it’s best to wait to use your discount until your tank is almost empty.
I have on occasion made people who are riding in my car very nervous because I will drive until I have only a few miles’ worth of gas left before I fill it up in order to save as much money as possible.
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I had a little less than a gallon left in my tank when I decided to fill up the other day.
I was sitting on an 80¢-per-gallon discount for Shell gas. The easiest thing for me to have done would have been to go to the nearest Shell station and fill my tank with 89 octane mid-grade, which would have cost me $3.01 a gallon with my grocery-store discount – or $45.01 for the 15 gallons I needed.
Would I have saved money by mixing 87 and 93 octane?
Ordinarily, that would have been the way to go. But if I bought ten gallons of regular and five gallons of premium, my grocery-store discount would have applied only to my purchase of regular.
Let’s do the math. Ten gallons of regular at $2.21 a gallon ($3.01 minus the 80¢ discount) plus five gallons of premium at $4.01 a gallon adds up to $42.15.
That’s a 6.4% savings. Not bad, but could I do even better?
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I usually fill up my car at the neighborhood Marathon station, which consistently sells gas for significantly less than the Shell station. (Both Shell and Marathon offer gasoline that meets the “Top Tier” standard established by leading automobile manufacturers, so I’m happy to buy either brand.)
But I can’t use my grocery-store discount at Marathon stations – it’s good only at Shell stations.
Gas at the Marathon station currently costs $2.83, $3.23, and $3.49 respectively for regular, mid-grade, and premium.
So filling up with 15 gallons of Marathon mid-grade would have cost me $48.45 – quite a bit more than I would have paid for Shell gas if I had applied my grocery-store discount.
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If I mixed my own 89 octane at the Marathon pump by buying ten gallons of regular and five gallons of premium, I would have paid only $45.75 – still almost 8% more than what I would have to pay at the Shell station.
So did I go to the Shell station and fill up my car with a mixture of regular and premium?
No way, José!
What I did instead was to go to the Shell station and buy ten gallons of premium, which cost $2.21 a gallon with my grocery store discount.
Then I drove a few blocks to the Marathon station and bought five gallons of premium at $3.49 a gallon.
The total cost? $22.10 plus $17.45 for a total of $39.55 – that’s an additional savings of 6.1%.
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Some of you may think all this is waaaaay too much trouble. You’ll prefer to just fill up your tank with 89 octane mid-grade rather than mixing your own by purchasing regular and premium separately at the same station – much less going to two different stations.
Either you’re made of money, or your parents didn’t grow up during the Depression – neither of which is true for me.
There’s one other thing. I’m as big a fan of free-market capitalism as you’ll ever meet, but I get a nice warm feeling inside when I figure out a way to stick it to a big business – even when only a few dollars are involved.
So screw you, Shell Oil (which had $284 billion in total revenues in 2024)!
And up yours, Marathon Petroleum (which brought in $138 billion in that year)!
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2 or 3 lines (with total revenues of under $100 last year) is bending you over in the prison shower and having its way with both of you – and I’m telling all my loyal readers how to do the same!
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Click here to listen to Cheap Trick’s somewhat creepy “Daddy Should Have Stayed in High School,” which was released in 1977 on the band’s eponymous debut album. (Somehow that album failed to crack the Billboard 200 album chart.)
Click here to buy “Daddy Should Have Stayed in High School” from Amazon.