Mix the mid grade yourself and save?

So I have to confess I'm pretty cheap, not cheap enough to drive all the way across town to save a few cents on fuel cheap, though.

I had an article hit my news feed today telling a bit of the history of where mid grade unleaded came from, that it is almost always mixed at the pump, and how they like to gouge you extra for the mixing sometimes. I filled my 1500 up today. We're towing our camper so mid grade it is. I noticed the price of mid grade was 20 cents more expensive a gallon over just buying half regular 87 and half 93 octane and mixing it in the truck. So that's what I did. I've never paid attention to this before, just filled it up. I'll pay a little more attention in the future. Maybe just a fluke today, but doubt it.

I read the same article today.

How much did you save? Compare what you paid to mix half and half. Then multiply the gallons pumped times the mid grade price.

Not worth the time to save a few nickels, to me.

Of more importance is how the engine responds to gas that is NOT mid grade. Advertised mid grade is a blend of low and high octane. The molecules don't cancel each other out. Low octane combusts earlier, high octane combusts later.
My hypothesis is it's better than low octane, but not as good as a real mid grade.

My plan this summer is to fill up on high grade octane at Costco during off-peak customer hours. Here that is before 9 AM and after 6 PM. Otherwise the waiting lines are long and often backed up out into the street. Not convenient for a full size truck driver.

I'd bet you can't find a single station that isn't using blender pumps. The tank information is always listed somewhere, contents and capacity. There's never an 89 tank.

Blend away on your own if you so please.

The math is pretty easy. Subtract the price difference between 87 and 93 in your head and add half of that to the 87 price. If it's much cheaper than the mid grade price and you don't care about the extra time to pump twice why not? In this case it was 20 cents a gallon cheaper, so maybe I saved almost the cost of a beer (told you I'm cheap).

Jas34 said:

The math is pretty easy. Subtract the price difference between 87 and 93 in your head and add half of that to the 87 price. If it's much cheaper than the mid grade price and you don't care about the extra time to pump twice why not? In this case it was 20 cents a gallon cheaper, so maybe I saved almost the cost of a beer (told you I'm cheap).

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Yeah, well you can't do that without knowing what the prices are, right? So in your case, at your pumps, it was 20 cents a gallon cheaper. A couple, three dollars per fill.

If you are pumping the same amount of low octane and high octane, add the costs per gallon, then divide by 2. Then compare that price to the mid level.

Now you're going to bring out the keyboard combustion engineers....

Jeepwalker said:

Now you're going to bring out the keyboard combustion engineers....

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To date, we've discussed differing compression ratios between 5.7 and 6.4 Hemi making impact greater on 5.7 with higher CR. But - 5.7 Hemi isn't used to tow like 6.4 Hemi does.
The higher the CR and load, the more precise the octane needs to be for static spark timing.
We discussed knock sensors work be allowing cyclic knocking before reducing timing long term. Not a good engine longevity design.
I always run 89 at least, plan to go to premium when towing.

Not every octane booster works, only use certain ones. Lucas is one that actually works, there is a test on the net out there somewhere. Most of them actually do not work if you believe the test.

I think I posted it here before, check search dunno.

@Burla - I'm succumbing to COSTCO-itis. Since all of these recent corporate consolidations, COSTCO is one of the few still holding firm on Top Tier gasoline additization, along with bulk low pricing.

Too successful. They're always crowded to the point of overwhelmed here.
To negotiate my big Ram Truck into their tiny corner lot will require planning on my part. I guess that's the price of modern life - you don't get to do anything you want in today's retirement. Before 9 AM, after 6 PM, according to their online activity data.

I'm a retired fuel tanker driver.
When loading we input the octane rating and gallons for the order, and yes, most stations blend at the pump for mid-grade. The trucks have compartments to keep each grade separated, and there are separate tanks underground.
There is a chart for stations that actually got mid-grade fuel that we would use to load the correct mix of regular and premium, "blending" right at the truck when loading mid-grade.
Another fact, all refined gasoline is the same. The difference is the additive package which is injected when loading for different brands or EPA regulations.
Winter and summer fuel is different, there is a changeover at the refinery, IIRC it is Nov1 and May1.
I would alternate filling my performance vehicle, regular one time premium the next, at about half a tank.

Interesting concept. Just looked at the prices at some stations and did the math....3 stations in different towns (though not that far apart) with slightly different prices. At those prices mixing regular and premium together 50/50 is the exact same cost as just all mid-grade. Would be curious how consistent that would be as the prices fluctuate.....never paid that close attention to if the prices all rise and fall at the exact same proportion or not.

Current prices are $3.24 - $3.74 - $4.24

So if you got 20 gallons total:

50/50 mix of regular and premim
($3.24 x 10 gal.) + ($4.24 x 10 gal.) = $74.80

All mid-grade
$3.74 x 20 gal. = $74.80

Coincidence or not?

I used to do this at costco to get 89-ish (CO had 85 and 91), but eventually got tired of doing a second transaction and holding up the line so I just filled up with 91.

joesstripclub said:

I used to do this at costco to get 89-ish (CO had 85 and 91), but eventually got tired of doing a second transaction and holding up the line so I just filled up with 91.

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yup, my truck is a dog on 87, I would use 89 if costco had it, but the engine does roar on 91. It is night and day difference for me 87 versus 91 since new.

sometimes if I am filling it and it's over 1/2 full I put back 87, seams to not know the difference at that point. I do have lucas octane boost on hand in case I get hesitation.

Racer9 said:

I'm a retired fuel tanker driver.
When loading we input the octane rating and gallons for the order, and yes, most stations blend at the pump for mid-grade. The trucks have compartments to keep each grade separated, and there are separate tanks underground.
There is a chart for stations that actually got mid-grade fuel that we would use to load the correct mix of regular and premium, "blending" right at the truck when loading mid-grade.
Another fact, all refined gasoline is the same. The difference is the additive package which is injected when loading for different brands or EPA regulations.
Winter and summer fuel is different, there is a changeover at the refinery, IIRC it is Nov1 and May1.
I would alternate filling my performance vehicle, regular one time premium the next, at about half a source.

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Helpful background, thanks.

We still see there is no real refined midgrade octane gasoline. Whether it's blended at the truck terminal or at the gas station, midgrade is still a blend of refined premium and regular octane gasoline, yielding questionable engine combustion.

I should tow with my performance tune with premium gas. That would advance ignition timing to use premium so as not to leave unburned carbon deposits from stock timing for midgrade octsne.

While my v-6 uses regular, based on various trusted sources, i use the mid grade for small engines - chain saws, lawn tractors, lawn mowers, out board motors, wood splitter, weed wacker, leaf blower.

In my town, my go to station is Mobil, a top tier gasoline that has the detergent additives necessary for contemporary engines. Currently, these are Mobil prices at the station- $3.19 regular, $4.04 mid, $4.44 premium. So 20 gallons of mid grade gas would cost $80.80. However, if i blend 10 gallons of regular ($31.90) with 10 gallons of premium ($44.40) the cost would be $76.30, or a savings of $4.50.

Burla said:

yup, my truck is a dog on 87, I would use 89 if costco had it, but the engine does roar on 91. It is night and day difference for me 87 versus 91 since new.

sometimes if I am filling it and it's over 1/2 full I put back 87, seams to not know the difference at that point. I do have lucas octane boost on hand in case I get hesitation.

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Look up Boostane Mike,it's the go to Octane booster in the racing world. It also doesn't turn things like your plugs as orange as Lucas does.

Generally, mid octane is a waste of money for small 4 stroke motors, and can cause more engine deposits - if they are low compression ratio - like Briggs and Strattons (6:1 CR). There is no need for higher octane until getting into higher CR's, typically more than 9:1.

2 stroke motors are entirely different, require mid to high octane gas without any alcohol (exception - direct fuel injected). My dumb buddy just bricked his Stihl 026 saw with ethanol gas. Dissolving his plastic carb and scoring his cylinder. Now he finally listens to me. My 026 saw is 34 years old and runs like a top. Inspected cylinder recently - you can still see the piston skirt machining marks with no wear or deposits. Hundreds and hundreds of hours on it. I'll post pic again if you want to see.

Mobil is Top Tier Gas, but usually doesn't offer nonoxy.
For small engines, I get non oxy (alcohol) 87 octane gas at Cenex. Cenex is Top Tier detergents, also. Oddly enough, Cenex is a major promotor of alcohol gas and political lobbying for tax money. Go figure.

Alcohol gas doesn't store well, even with stabilizer. Small engines don't like it with plastic parts in them - plastic carburetors and gaskets, etc. They get dissolved. Further, alcohol leans out small engine mixtures and causes engines to run too hot. Finally, small engines have low compression ratios that don't want higher octane or alcohol. They cause excessive unburned fuel deposits on heads, valves, and rings. Esp. flathead engines.

It's a shame EPA and corporations have made something relatively simple a complete mess for consumers.

Wild one said:

Look up Boostane Mike,it's the go to Octane booster in the racing world. It also doesn't turn things like your plugs as orange as Lucas does.

Racing Octane Booster | BOOSTane Professional

BOOSTane Professional is our award-winning octane booster for racing, allowing racers to raise their octane level as high as 116.

boostane.com

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Know anything about Optilube Cetane Boost for diesels?

HEMIMANN said:

Know anything about Optilube Cetane Boost for diesels?

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Nope,i don't play with diesals,lol.