Regular vs. Premium Gas - a perspective

With the test I did a more than decade ago, when fuel prices were extremely high. I compared high octane and low octane/ brand name vs generic. The test was mainly for saving money at the pump, getting the best mileage for you buck. The test vehicle with my 2005 DC driving mostly flat and minimal hills. Mostly interstate 400+ miles each way. I concluded that my mile per dollar savings is favoring some generic fuel vs brand name or high octane. I did notice some engine performance differences mostly when passing, not 0-60. I felt this too with my Corollas na and boosted.

I might consider doing another test with the '20 Tundra and see. Using Costco 87/92 vs Shell 87/92. It might take a good 4 fill ups of each brand and grade to minimize contaminants of different brand and grade. It's going to take several weeks to get this right. Nope, too much work and I know I'll forget and fill it with the wrong fuel and mess it all up.

As for the ethanol free gas vs with. I use ethanol free gas with my old engines and small engines. Ridgid with a Subaru engine pressure washer, valve stuck bent rocker arm. Generac B.S. engine, ate up the rubber bushing between the tank and hose coupling. Honda/Troy/Husqvarna, mowers bent valves. Trimmers, I buy a new one every two years. 1.6L 4A-GE/GZE valve stuck. After switching 15 years ago, I did not have any problems anymore. Ethanol is bad. It's corn, you can not digest corn.

I read somewhere that fuel with ethanol breaks down after two weeks. That may be the case with my Miata that I only start-up/drive every two months.

 

Well do these 5.7s have an automatic timing adjustment for higher octane fuels? Never read that but doesn't mean it doesn't exist.

My Acuras all have it. You can run regular or premium. If I run premium, the engine detects it, adjusts timing and WOW - extra power. It's about the difference of having the A/C on or not (but keep in mind an a/c makes far more impact on a 4 or 6 cyl), hardly any on these 5.7s. Calculating mileage between fillups consistently turned out 10% gains on premium.

But again, do these 5.7s adjust timing for octane, anyone know for certain? : ^ ))

 

I know that I get a very poor mileage with E85 vs 87 octane on my '16 with Flex Fuel option. You're not saving any money. Toyota eliminated the FF option in the '20 models. I am not sure if Toyota programmed their ecu to read different grades and different types. I hope they did. That will be the smart thing. I know with the VW GTI's you can use both regular and premium. We fill it up with premium before an even and regular on the way home.

 

in Texas, QT (quick Trip) sells ethanol free, 90 octane fuel. switching from 93 octane to the ethanol free fuel raised my mpg by about 2.0 mpg. with that mpg increase, i would suspect that there is a small hp increase as well (my truck is also tuned). it would be nice if all fuel did not contain ethanol

 

Maybe I am not that sensitive, but when I tried high grade gas, I saw no difference (in how it drove, in power, in mpg). So I went back to regular gas. No issues.

 

+1

 

I found this quote from D.A.P. tuning. Not sure really what he means or how he came about it.

"To all You non believers about Octane differences. It’s real, so now I have confirmed, stock 5.7L and 4.6L absolutely hate 87oct gas. I’d advise if you love your vehicle, quit running trash gas"

 

https://www.tundras.com/threads/octane-if-towing.58550/#post-1534323. I think it may make a difference with towing.

 

Compression ratio and timing. To much advance. I have a 1969 Corvette. The compression ratio was greater than 11:1. I used 93 premium. Still wasn't enough. The engine would knock and "run on" when I shut it off. Not to mention the damage to the forged pistons. The knocking or pre-detonation made a mess of the pistons. Chips from the constant detonation. Guess it needed the good old Sunoco 260. The next rebuilt, I cut the compression ratio.

I have taken trips with my wife's new Civic and swapped between regular and premium. I see (gas mileage) no difference. However, if I tow heavy loads with the Ridgeline, I do see a difference. I think with regular and under load, the engine may "knock". The knock sensors pick it up and retard the timing to protect the engine. Retarding the timing knocks the bottom end out of your performance and gas mileage. At least that is my theory.

 

I don't think you're wrong. I do think that if every tank of 87 was equal it would fuel our engines to the spec'd performance. However, there is reason to believe that not all fuel is created equally well. Most of the testing we read is with carefully selected fuels to eliminate variability. There is more to gasoline than octane. For instance, RVP varies winter to summer and per published requirements, but must always be well controlled for higher altitude performance.

Too high an octane rating will burn valves because octane is resistance to detonation and it can still be burning when the exhaust opens before the charge is burned. Higher octane is required for higher compression. Ironically though, some of the lowest compression engines I've seen use the highest octane. Take the aircraft engine, R4360 Pratt & Whitney radial, 6.7 to 1 compression, 115/145 avgas. Supercharged of course, and that changes everything. Seems like I saw a grenaded Tundra engine on Youtube a while back that was supercharged and had gotten a tank of poor quality fuel.

I haven't researched how our engines control detonation but I do suspect 93 octane fuel is probably a higher quality product overall and you're feeling smoother performance, maybe no increase in economy or power, just smooth, problem free power.

 

I did about 60 repeating trips, ~1K miles each way with mountains, towing an enclosed tandem cargo trailer usually, and sometimes a tandem flatbed. Typical load 5K, but went up to max a time or two. Can do the route blindfolded at this point.

I had better range with premium, and could hold a given gear better going up a grade, and I didn't want to take chances with detonation in high summer heat.. so ran premium almost always.

When not towing, I use regular (or reg'lar, as those weird Oregonians say).

One memorable run I was hauling a full size Bronco on the flatbed and additional cargo, going north on I-5 toward the Oregon border in Kali, hot as heck, steep grades, in the left lane passing.. basically everyone. 5.7 + 4.30.. beastly. I run RedLine 5w30 at 10K drain intervals since the truck was new, and RedLine gear oil and grease for the driveline. The driveline is serviced regularly. Tranny is drained and refilled every 1-2 oil changes, so the ATF is kept fairly fresh with these partial replacements. So far, 100% reliability.

 

Should add that I don't have an extra oil or ATF cooler, beyond what the factory tow package provides, and I didn't have an OBD reader hooked up live so I don't know quite how hot the ATF got hammering up the grades full throttle. I figured I'll err on the side of caution and just do these partial replacements.

I didn't do UOA, but the fluids come out looking and smelling ok. Either the front diff or T-case was darker and nastier than I anticipated, forget which. I think I have those on a 25K drain schedule. The five u-joint zerks and yoke 5-10K.

Now past 100K replacing the OEM Bilstein 5100s, I think they are, with fancy King 2.5" remote reservoir on all corners. OEM shocks are tired after dealing with all the trailer inputs. The flatbed when empty is ridiculously springy and bouncy.

All told, the Tundra has been great as a four-season working truck. I spent many a night in the back seat, usually some forest service road, so much quieter than a rest stop stuck between the reefers. Wearing its third set of 10 ply BFG A/T KO2s, mountain-peak-and-snowflake rated. Love these tires. Pricey, but so good all year round.

Just my 0.02 from the road...

 

I can only speak for Shell because I lost a bet on this. I ended up talking directly to a Shell engineer. He told me the "add pack" is different (i.e. detergents, etc) for their 93 octane blend. That's only Shell and it was about 5-6 years ago, but there ya go.

 

The legendary 4.7L Tundra V8 engine was built for third world conditions and is the reason for its longevity. It requires 87 Octane.

I prefer using St. Barts Gas n’ Go as their quality is always top notch compared to Sheetz.

 

Well first of all I call BS on the comment that by using 87 Oct regular unleaded gas on a vehicle that was designed to be run on 87 Oct gas will trash your truck. I drove my last Tundra 12 years without a single fuel system issue.

http://news.aaa-calif.com/internal_...46/files/20168/Premium-Fuel-REPORT-FINAL2.pdf

This study was extensive and it was performed in a controlled environment with data logging and standardized test controls as well as a 2016 Tundra and 2 other control vehicles.
It basically says with any of these 3 vehicles, if you run high octane fuel instead of regular, they found no real difference in fuel mileage, performance or tailpipe emissions. As a matter of fact they saw a decrease in MPG with the 93 Oct

 

Whaaatttt? Actual data?

These gas mpg threads are a perfect example of why I shoulda got into marketing and sold bridges. Couple checkered flags and make the pump a fast looking color...bam, half the population says ”holy shit! its better! I can tell!”

But shit, this is ‘Merica boys...I run Amsoil in everything I own, I know im wastin’ my coin but its blended, bottled and made in the greatest country on earth. Take my money!

 

Everybody's gas is different, every State has different standards/EPA requirements (blends). There are over 50 blends of gas in the US (not 3-6) - its because the Feds left up to the States to mandate the cleanliness of gasoline. This not only varies State to State but within States (municipalities). The reason gas is so expensive in Illinois (over and above tax) is because of additional requirements. Gas in St Louis MO is completely different than gas in East St Louis Illinois 3 miles away across the river. Thus all the "studies" cited are a bit flawed, your not comparing apples to apples, also explains why Dave in one State can run low grade gas and it runs his great and sees no difference and Sally in another State says premium is the difference maker. Hell in Illinois there are additional requirements/blends for winter vs summer. Typically the bluer your State the more "requirements" your gas will have making it more expensive over and above taxing. In other words its a PIA for refineries.

 

Using Costco gas prices around me as a reference, premium costs 20% more than regular. The car won't run 20% better or 20% more efficient so I'll continue using 87.

 

Same with Exxon/Mobil, though that was more recent

 

The "requirements" you are talking about have zero effect on MPH or Performance. These are emissions only and have zero impact on this study.
So you keep on believin brother.

 

As per personal experience I honestly believe that ethanol free gas gives better gas mileage. I drive a '17 5.7 FFV crew max. I wanted to try use the 10% ethanol content gas (89 octane SHELL) and I start getting 310 miles per tank (26 gallon) . Using ethanol free (89 octane SHELL) I was getting 350 miles. I usually fill up when gas lights comes on and it will take 20 gallon to top or off. Doing the math correctly I'm losing 2 miles per gallon.
I will definitely switch back to ethanol free gas again and stop listening to my wife's advice, she swear that with ethanol gas her HIGHLANDER drives better!

 

If I may ask: What exactly did they engineers say? The "add pack" may be different. But what would be the benefit of the Premium gas add pack (if any) over the regular gas add pack?

I am not sure, but I thought somewhere I read that they market premium with "has super detergent in our premium for a cleaner engine". What they didn't mention is that the same "super detergent" is in regular too. I guess the omission is not a lie. Which makes me wonder if the % profit is higher on premium gas, if they are marketing it over regular.

But you or DAX15 can remember and elaborate further, I would be very interested in what the gas engineers said.

 

Found this at https://f30.bimmerpost.com/forums/showthread.php?t=1289771 (just part of the post)

While ALL Shell gasoline grades contain the patented nitrogen enriched detergent package, Shell V-Power NiTRO+ Premium gasoline contains the highest concentration of the cleaning system (approx. 7X the amount of detergent required by the EPA). In fact, the 87 grade has approx. 50% of the amount of nitrogen enriched detergent add pack as the Premium V-Power NiTRO+ product. That would also mean that the mid-grade would have approx. 75% of the amount in the V-Power NiTRO+ product, etc.

Happy and safe motoring!

Regards,

Mitch
Shell Solutions Center"
__________________

 

So how much how detergent is there in a gallon of gas?

I've always been kinda curious about that cause you are paying a premium already. Then if there's actually a significant amount of additives compared to the actual gas per gallon.... Eh... I'm not even sure why I'm curious, I only get 87.

 

Oh certainly 93 isn't enough for high compression engines. If you remember the late 60s and early 70s regular was somewhere around 97 octane and premium was 102+.

 

If ethanol some how increases octane rating, what's truly behind this gasoline with 10% ethanol content in terms of quality? You get what you pay for and if 89 ethanol free is still higher or about the same of 93 octane with 10% ethanol, does it tell you anything or what's your opinion on that? I believe the problem here is relevant to a certain extent when we talk about octane rating, the main issue I believe it's the ethanol they put in.

 

Ethanol does increase the octane rating. My guess is it allows for less addition of MMT for the gasoline portion. I would pay for EtOH free, but the stations are hard to find and not that many.

Probably the reason that EtOH free is more expensive is that it's a specialty product in the distribution chain. Not to mention EtOH is highly subsidized. You lose about 4% mileage with E10. And you are basically putting in 1/10 of a gallon of water for every 25 gallons of fuel.

 

Yep, I remember getting Sunoco 260. Also, on the way to Bridgehampton Race Circuit, there was a gas station that sold racing fuel. But as the years went on, Sunoco 260 and the racing gas went away (except in remote areas). Plus I never found an octane booster that seemed to work. The new engine has a much lower compression ratio.

 

I know when I put e-85 in my truck the mileage and power sucked...bad. It took a few tanks of regular to get it worked out and get back to normal fuel mileage. With that in mind, I would think that the 87 vs 93 you would want to run a few tanks through before starting the data collection. As far as regular vs a 10 or 15% ethanol blend, it is cheaper, but you are getting less power per gallon.