An Oct. 2, 2026, post by Garrett Gleim on the Gleim Aviation website caught my attention. From Garrett’s post:
Avgas does sell at a premium over motor gasoline at the refinery gate, but that premium has to cover dedicated tankage, specialized handling, product liability, and a batch-certification process that ordinary gasoline never needs. Typical gasoline margins are thin to begin with, so when gasoline profitability widens even modestly, the math can tip: That same barrel of alkylate is worth more staying in the mogas pool than going into a specialty product that represents a rounding error of total output.
I wasn’t aware of those nuanced details.
And this:
Here’s the part that catches most pilots off guard: Avgas isn’t produced continuously. It’s built in scheduled batches, blended, and certified in discrete runs rather than flowing off the line around the clock. If a refiner looks at a wide gasoline crack spread and decides the timing is bad, it can simply not schedule the next avgas campaign. There’s no press release, no announced closure, no dramatic news story. The batch just doesn’t happen, and the gap doesn’t show up until tanks downstream start running low.
Count me as “off guard.”
And what the heck is a “crack spread?”
According to Garrett, “A crack spread is the difference between crude cost and the value of the finished products made from that barrel.”
The most interesting part of Garrett’s post was this chart (above). Garrett included 2005-2025. This version, which is a screenshot from the U.S. Energy Information Administration (EIA) website, goes back to 1981.
Generally, I’m a positive person, but this chart looks like we’re flying into an area of ever lowering overcast cloud deck. Thankfully the X axis isn’t climbing up to meet us.
Be sure to read Garrett’s full post here.
The flip side is that Avgas has a very long shelf life compared to gasoline. So, even though the production runs are short, it can remain in tanks for a long time before deteriorating. Mogas of the highest AKI rating (93) has a longer life than the lower AKIs, and is filtered better. That is probably why we used to call Amaco’s high-test “white gas” as it was relatively clear compared to amber-colored gasoline of lower ratings. The bottom line remains – ethanol-free mogas of 91-93 AKI remains the most important aviation fuel we have. And it exists in very abundant volumes compared to boutique aviation fuels. The only problem is distribution and storage, which is an easy problem to solve if Avgas sellers would simply support it. It is available on all GA airports in Europe, and delivered by the same fuel providers that bring them 100LL.