Short article: You’re All Wasting Billions Of Dollars On Premium Gas, So Stop It


 
That article was quite lengthy, and I only read part of it, but what if an engine recommends higher octane? Is their a difference between "recommended" and "required"?
 
There have been many tests and article on this subject. You could destroy your life reading it all. But in the end, if it says use regular, use regular. If it says use supreme then use supreme.
 
George Curtis said:
There have been many tests and article on this subject. You could destroy your life reading it all. But in the end, if it says use regular, use regular. If it says use supreme then use supreme.
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I agree (don't know about destroying my life reading about it but I guess it's a deep rabbit hole :) ).

Consensus from my limited reading/understanding over the years seems to be that if the engine pings then you need higher octane. I'm not sure I've ever heard an engine ping so :confused:

I was considering installing a high-compression piston & more aggressive cam in my harley 103ci after seeing what it did to my XR650L (mine's the most PO'd in town......in a good way), one hobby-racer said I'd have to run race gas (leaded, and not widely available) if I did that to the Harley or it'd ping. :confused: again.

One chain of gas stations around me has a choice for ethanol-free gas so I tried it - didn't notice any improvement in mileage after one tank so I didn't buy it again. I probably didn't give it a fair chance but I do a quick mileage calc ~30-50% of each fill up, so I knew what to expect (wasn't impressed).
https://www.pure-gas.org/about

Last year at about this time I did a ton of vehicle maintenance - changed the plugs in one van & my truck (150K & 130K miles), FLUSHED transmissions, new trans pans/filters (took >13 gallons in the 3/4 ton van)....etc etc etc. I ran marvel mystery oil in the trannies, crank cases, & fuel tanks, fogged with Sea foam before the maintenance. No diff in performance. New air filters (xfer case & diff fluids too), nada. But they're still clean...... and due for minor maintenance again ( :( why do I have so many vehicles to maintain)
 
You won't hear pinging/knocking in most modern (less than 30ish years old) engines, knock sensors are pretty common. Easy to tell if they're working, at idle, tap the side of the block with a ball peen hammer, generally close to the sensor, and see if the ECM retards the timing and brings the idle speed down.

Still, the article probably does bear repeating. There's no more energy in 103 octane over 87 octane. The only significant difference is knock resistance, which is useful in high compression engines.
 
I don't think I can recall any modern (post OBD II) vehicle that does not have a knock sensor (sometimes more than one). That being said it does not negate the need for premium fuel on engines that actually call for it. Bottom line will it "hurt" an engine that requires premium to run something less? Perhaps. Though it may hurt performance and MPG substantially if all the programming (timing, fuel trims, EGR time, you name it) is designed with premium in mind. Some cars come with a "premium recommended" for better performance. My daughter's Lexus ES330 and my wife's Toyota Highlander V6 both have this "recommendation". We tried premium in both engines and did notice a SLIGHT avg MPG improvement but not nearly enough to justify spending nearly $1.00 more per gal. Now on engines requiring it the computer will do everything it can to prevent knocking but in some cases it just cannot do enough. Or it may need to pull back the timing curve and cam timing along with other things that it could cause severe performance and perhaps even longevity issues to the engine. Bottom line if it says "required" use it if it says "recommended" you have to do the math and determine if it's worth the cost. Otherwise yes it is a total waste of $$$. There is nothing to be gained as even almost ALL regular grade fuel these days is specified as "top tier" and has all the necessary "stuff" to keep valves and injectors clean
 
As he said (what is recommended by the mfg). My magnum wants mid level. So I do. I know what my milage/gal is. Early in my ownership I tried reg because it was cheaper. Miles per gallon went down about 10% IIRC ---> to compensate, engine adjusts for lower octane by using more fuel.
 
Actually the adding more fuel thing is not 100% accurate. The easiest and best way it does it is by cutting timing back and adding more exhaust gas recirculation on engines that have it (less common in VVTI engines) and or change exhaust cam timing to allow more exhaust to stay in the cylinder to cool down the fuel charge. Both of which substantially cut into performance and economy. Adding more fuel would cause CO and hydrocarbon emissions to skyrocket or overwhelm the catalyst(s)
 
It used to be that all grades of gas were within 10 cents of each other, with a 20 cent difference between unleaded and premium. Now, there's much bigger price gap than before.
 
Bob H. said:
So, if I had a Porsche Turbo I should just burn regular? Not a chance!
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The article is VERY misleading and for the most part VERY wrong. The thing is there are some vehicles that indicate "premium fuel recommended" for best performance but regular can be used with no issues. These vehicles MAY not WILL see a performance and MPG gain on premium. However they may not and even if they do it may not be enough to offset the cost difference (which around here is close to $1.00 a gal) YES you read that right. Just went to a station recently and regular grade was 2.83 and premium was $3.60. Ou'd have to see a WHOLE LOTTA gain to make that worthwhile.
Now there are some that read differently "premium fuel REQUIRED" Huge difference here and regular fuel in this vehicle COULD cause engine damage, WILL cause severe performance hits, and will not allow the vehicle to run correctly overall right down to the automatic transmission not working correctly.
 
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