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Using an Octane Booster additive to save $$?

3K views 23 replies 8 participants last post by  CVTMiniDT 
#1 ·
I saw a bottle of STP Octane Booster 350ml for AU$5 (~US$3.50). In Australia, 91 RON octane fuel sells for AU$1.50 - 1.99/liter at present & 95 RON (recommended for most BMWs) for 10-18c extra. If the additive raises a 75L tankful to 95 RON, the saving per fill is AU$7.50 - 13.50 minus the $5 it costs.

The packaging simply states to add the booster to a tankful of fuel - no question about the tank capacity or of how much it raises the RON by! Has any one had experience with this type of product.

I'm aware da Putz is a tyre whisperer & have read of the shandy he makes mixing different RON fuels (gas whispering?) but has he produced an Excel spreadsheet on using octane boosters like I saw.
 
#2 ·
In my opinion, adding the octane booster will end up costing more than buying 95 RON, the key point being that you do not yet know how many bottles are required to really get the tank up to the equivalent of a tank of 95.
 
#4 ·
I saw a bottle of STP Octane Booster 350ml for AU$5 (~US$3.50). In Australia, 91 RON octane fuel sells for AU$1.50 - 1.99/liter at present & 95 RON (recommended for most BMWs) for 10-18c extra. If the additive raises a 75L tankful to 95 RON, the saving per fill is AU$7.50 - 13.50 minus the $5 it costs.

The packaging simply states to add the booster to a tankful of fuel - no question about the tank capacity or of how much it raises the RON by! Has any one had experience with this type of product.

I'm aware da Putz is a tyre whisperer & have read of the shandy he makes mixing different RON fuels (gas whispering?) but has he produced an Excel spreadsheet on using octane boosters like I saw.
I woke up with my ears burning.

Here's STP's US website: Octane Booster | STP®

It says that STP Octane Booster contains MMT. MMT is a metallic compound that damages catalytic converters. From Uncle Dougie's post above, it's mostly "hydrosulpherized kerosene." Sulpher is also bad for catalytic converters.

It also says that it cleans the fuel intake system. I'm not even sure what a "fuel intake system" is. In port fuel injection engines, fuel in sprayed on the top of the intake valves. Sufficient additives in the fuel will keep deposits from forming on the intake valves. In direct fuel injection (like all BMW's for the last maybe 15+ years), the fuel goes directly into the combustion chamber. So, it can't clean off the top of the valves.

The gunk that clogs up an engine's intake system and fuel injectors started out as gasoline and engine oil. A cleaner that breaks down that gunk can also break down engine oil and its additives. I saw a KIA service bulletin somewhere that said only add fuel injection cleaner just before an oil change.

It doesn't say specifically how much it will raise the octane rating of a specific volume of gasoline. You're just assuming it would raise 75l of gasoline's octane rating four RON points.

Here's something off the Interwebs saying that STP Octane Booster only increases octane by 0.2 to 0.5 RON. That's far from the four RON you used in your calculation.

Does Octane Booster Work? - Best Fuel Octane Boosters (tuningpro.co)

The reasonably accurate equation for blending octanes is:

Octane = (1 /Total Fuel Volume) x [(Octane #1 x Fuel Volume #1) + (Octane #2 x Fuel Volume #2) + ... ]

The US measures octane in AKI. 87 AKI is roughly 91 RON. 91 AKI is roughly 95 RON. Big Oil and Big Car are both lobbying the US government to make our regular gas 91 AKI, up from 87 AKI.

BMW's in the US need 91 AKI to perform as advertised. In much of the country, gasoline is sold at 87, 89, and 93 AKI). Using the equation above, 1/3 87 AKI and 2/3's 93 AKI makes 91 AKI. Here in Bubba County, Floriiduh 93 AKI is $0.80/gallon more than 87 AKI. So, blending gas for my 17-gallon fill-up saves me $4.53. Over the 100k miles I keep a car, gas blending will save me over $1000.


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#5 · (Edited)
Ooooo kaaaaay! One spreadsheet.... coming up!

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Yellow cells are user input. Green cells are output.

I made an instruction sheet for Frau Putzer to use when she fills up the X3 Frauwagen. I printed it on heavy-stock paper and had it laminated. I put it in the pouch on the back of the driver's seat. She looked at it and said "Do you want me to used regular or premium?"
 

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#7 ·
Try also extra virgin olive oil instead of engine oil. But, make sure it is extra and not just regular olive oil.


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Frau Putzer's friend owns a fancy Italian restaurant that serves breakfast on the weekends, and serves olive oil on orange slizes. Mmmm.... tasty.

I carry bottled water in old BMW oil boxes when I'm on the road. I was unloading my car at a hotel. The porter saw the boxes and asked if my 535i burned a lot of oil. I told him no, but I use LL-01 on waffles and pancakes.
 
#9 ·
Use the OBC Correction Factor (%) (from the fuel logbook)
That's hurdle #1 right there, for those primitive organisms without the Sacred logbook.
But your whole mixing premise may be faulty: it assumes two gas grades have specific gravity close enough to blend into one without any phase separation. This is faith based. If the mixture is imperfect, the timing will constantly try to adjust and RPM would not be as smooth as $80k automobile should have. Beside the next guy in queue (that one in F-150 Raptor) may get all jumpy seeing you fiddling with different filling hoses, laminated cards and the log books. Having considered the prima facie evidence any jury will vote for the acquittal for him.
 
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#10 ·
Regular and premium gasoline have the same components, just in slightly different proportions. They mix quickly in the car's gas tank. 90.8 AKI will not affect performance.

Yeah, I track my correction factors (K). From this I can adjust the K in the secret instrument cluster menu. I do this about annually. The absolute values of the average of my K's for the last four fill-ups for both of our BMW's are less than 0.1%.

I hate waiting to buy gas. I use two local gas stations. One has eight pumps, and I'm usually the only one there buying gas. The other station has 32 pumps. I've found that Pump #23 gives away free gas, maybe 0.4%.

Gas station-convenience stores are pretty much the only place where the dregs of society and I cross paths. For this reason, I'm usually armed when I buy gas. The thresholds for using deadly force in Floriduh's self-defense laws are pretty damn low, actually hilariously low. Raptor Boy would do well to stay in his truck and leave me alone.

As soon as I pull up to the pump, and sometimes when I'm across the street at Sam's Club, I calculate how much 93 AKI and 87 AKI gasoline I'll need. It takes me one minute to reset the pump for the 87 AKI. Saving $4.50/tank, that works out to $270/hour for my time.

Gas Whispering, like Tire Whispering, works. Gas Whispering will save about $1000 over 100k miles.

Before Gas Whispering and Tire Whispering, there was Oil Whispering. I read about the advantages of synthetic oil back in April 1976.

Popular Science - Google Books

The Putzer cars in 1976 were either sludged up or leaking oil. So, I didn't start using synthetic oil until 1985 (when Mobil 1 came with 5W-30). I got tired of giving the "Putzer Synthetic Oil Speech" to people. So, I made... wait for it... a spreadsheet. It takes all the variables and calculates the extended oil change interval to "break even" on cost, and then calculates the cost savings from a further extended oil change interval. A conservative estimate of MPG gain is about 2%.

Back in the bad old days of conventional oil, 4000-mile oil change intervals were common and prudent. (Frau Putzer brough a five-year-old, 25k-mile Honda Civic to the marriage, and the engine had varnish with supposedly 3000-mile oil changes with conventional oil.)

One of the variables is the cost of the owner's time either doing an oil change or getting an oil change done. When I was working, my time was worth $50/hour. I was on super-gliding-flex time, and I changed my oil at work in about an hour (but off the clock). So, it was reasonable to add that $50 in as one of the variables.

Throwing all the variables into the Oil Whispering spreadsheet, switching to synthetic oil and extending the drain interval from 4000 miles to 7500 miles would save on the order of $70 (over 7500 miles). Over 100k miles, the savings would be on the order of $1000. Less engine wear and no engine deposits are qualitative benefits.


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The Oil Whispering spreadsheet would convince even my electrical engineer friends to start using synthetic oil.

Most new cars now require synthetic oil. So, the Oil Whispering spreadsheet is now pretty much moot. But, back in the day, it'd save my friends $1000 over 100k miles.
 
#11 ·
It says here on the bottle of BMW Techron Injector cleaner: "Pour into empty tank. Fill with up to 16 gallons of fuel". To an ignorant schmuck like myself this reads like they kinda not too sure the two will mix altogether that well otherwise.
 
#13 ·
Thanks to all for your replies. It appears Octane Boosters aren't an economic solution & may be a risk to 02 sensors & the catalytic converter. The great whisperer, Herr Putzer's shandy of different octane fuels appears to be the best money saver & is supported by yes, a spreadsheet.

I note that the ingredients in some boosters include toluene & methyl benzene which I used in my first car in the 1960s. It was the Australian built Austin Lancer - a badge engineered version of the Wolseley 1500 made by the British Motor Corporation. Mine was originally fitted with a 1.4L version of the B series motor which later progressed to 1.8L in the MGB. I fitted a 1.6L version from a MGA mk2 doubling the power to ~80BHP. The head had been shaved & it required methyl benzene added to premium fuel to prevent pinging. Methyl benzene was later found to be carcinogenic!
 
#21 · (Edited)
The wholesale price difference between 87 and 93 AKI is probably around $0.40/gallon. Gas stations will charge as much as they can get, though. People with newer, turbocharged cars have to buy 91 AKI or better. So, the gas stations stick it to them. Have you noticed that gas stations don't have their premium gas price on the large signs anymore?

My road trips north start with a 90-mile run though the boonies. Gas is cheaper in Alabama. Ideally, I leave the house with just enough gas to the first patch of civilization inside Alabama. If I don't have enough gas to get there, I occasionally fill-up with 93 AKI here and then top off the tank in Alabama with 87 AKI. This gives me a comparison of MPG and drivability with 91 and 93 AKI on those 90 miles of rural roads... no difference.

Big Oil and Big Car are both lobbying for regular gas to be a mandated 91 AKI (a.k.a. 95 RON). In the meantime, for most of the country, there's $4 to $5 "sitting on top of the gas pump," just for the taking.

I've been using "Auto's Custom Blend 91 AKI" in BMW's for 235,000 miles. My E46 M3 would ping on those rural roads at 55 MPH if I tried to accelerate without downshifting (6th to 5th). But, other than that 91 AKI is what BMW's are tuned to use and perform as advertised.
 
#22 ·
My point was that 89, being 67% 87 AKI, is priced closer to 93 (where the price of 91 would theoretically be) than 87. So, like you've stated, it's cheaper to make one's own than to buy it. The L83 V8 in my truck will ping on 87 under heavy acceleration, and prefers 89. Actually, it would happily run E85 all day every day (it loves it like trailer parks love meth) so it does, but cold-starting in winter puts too much stress on the starter, IMO, so come December it's back to "expensive" E10.

Down here in the South right now, I can't source E85 like I can in NY, so I had to play the mixing game on the way down just over the VA border.
 
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