I know all about the top-tier designation and that RT isn't on there (or certified by it/whatever). I've also seen the supposed studies that say stay with the TT brands. What I'm wondering is, based on my personal observations with my vehicle, is that really sound advice? Or is TT simply a branding that gas companies buy into and the fact that most of those that are in it happen to have better gas quality than most of those that aren't is simply a coincidence? Or, even if there being some basis behind it, COULD there be a brand (e.g. Racetrac) that still sells quality gas that isn't in the TT designation?

Since this past spring -- around the middle of March -- I've been tracking gas mileage heavily in my vehicle (2016 MDX, but I don't think that's relevant, at least not for now). I've done 3-4 fillups at a time at most of the major stations -- Shell, Exxon, Mobil, Chevron, Gulf, and Racetrac, as well as one or two at other places like QT. The QT and others had low performance in my view (MPG and throttle response, specifically) that I didn't do more than one tank. The others in the TT category ranked, in terms of MPG and performance, Chevron, Gulf, and Shell in front of Exxon and Mobil. In fact, Mobil was the lowest on this list, by far, in terms of both MPG and performance. My car was sluggish with it in, similar to with QT.

Racetrac not only blows these brands away in terms of MPG (at least 1 mpg more than the best; 2-3 more than the rest), it is no worse than as good as the better ones in terms of performance. I think I've had 6 RT fillups at 2 different time periods and every time I go back to Shell or Chevron (my 2 main go-tos in general), my MPG drops. Note that I've done this by hand calculation and by the car's and both results are virtually the same in terms of difference, which is all I'm concerned about. Also, please note that this is a study over 5 or so months and while the driving is varied between highway and city (I took a trip to Houston in June -- no apologies necessary), it has remained very consistent overall.

I'm not saying this PROVES anything, but I think I can post a hypothesis or two:

1. Would it be a better idea to focus on buying gas at stations that are busy and the gas gets turned over in the tanks more often than looking at TT status? The Racetracs I've used are indeed busy, as most of them generally are.

2. How can a gas that's arguably not as good from a technical standpoint -- as Racetrac gas supposedly is IF the TT designation is legit -- be at least as good in terms of performance and better in terms of MPG?

Thoughts?

A quick google search says top tier fuels require 8-10% ethanol. Maybe the base fuel for RT has lower ethanol and thus you get more bang for your buck in the mileage departemtn.

Personally, i don't give a hoot about any of that in terms of MPG or performance. I focus on buying quality gas that is turned over frequently. I think that is far more important, especially when dealing with ethanol based fuels, which all are now.

If RT is getting you results, then I see no reason to change from it. I don't think there is a hill of beans worth of difference between any of them in terms of actual quality. By that I mean, I don't think the top tier fuels are going to keep your vehicle cleaner inside, especially since most folks change cars like they do underwear. It's like hemming and hawing over motor oil. It's 2026...it's all good, it all meets the specs, it all works fine.

Very interesting test, though, and i don't doubt your results since they are repeatable. I think you are onto something.

Buying from RT is fine as long as you drop in the occasional fuel system cleaner with PEA, usually every 3k-5k miles. I like the Red Line Fuel System Cleaner for a comprehensive cleaning and Royal Purple Atomizer for a smooth ride.

91AggieLawyer said:

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Racetrac not only blows these brands away in terms of MPG (at least 1 mpg more than the best; 2-3 more than the rest), it is no worse than as good as the better ones in terms of performance. I think I've had 6 RT fillups at 2 different time periods and every time I go back to Shell or Chevron (my 2 main go-tos in general), my MPG drops. Note that I've done this by hand calculation and by the car's and both results are virtually the same in terms of difference, which is all I'm concerned about. Also, please note that this is a study over 5 or so months and while the driving is varied between highway and city (I took a trip to Houston in June -- no apologies necessary), it has remained very consistent overall.

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What is your average expected mpg?

If it's 20 mpg and you get 21 mpg with Racetrac but get 18-19 mpg with other brands, we're talking about a maximum deviation range of 15%.

"performance" is subjective unless you're going to the track or have a vehicle like a Challenger or Mustang or something that has the 0-60 timer you can set.

Varied driving conditions over a 5-6 month period isn't really a great test. Especially when you're not even filling up a the same gas station consistently.

As you obviously know, there are going to be a lot of variables in traffic, road conditions, routes, etc. Example, I'm sure the gas mileage was fantastic when you drove to Houston and back.

Also, when you fill up, are you putting 19 gallons in a 20 gallon tank? Or are you only putting 10 gallons in? So you've still got 50% of somebody else's gas in the tank.

A great test would be if you drove the same distances, driving conditions, road conditions, weather conditions and only vary the fuel. Very difficult to achieve.

Back in the mid-1990s, when Email listservs where a thing, I was on a mailing list for a particular car model that I owned at the time. One of the guys on the list decided to create a junk science hypothesis (on purpose, for a laugh).

He posited that the age of the gasoline made a huge difference in fuel economy.

His observation was that when he took a highway trip where he had to refuel after 6 hours, he got 30 mpg. But, if he left the gas in his car for several weeks, driving around town, his gas mileage was only about 22 mpg.

His conclusion (for fun) was that if you use newer gas, you get better mileage versus using old gas.

In the realm of what you're after though (I think), I can say for certain that some brands or grades of gasoline are awful and I won't buy them.

When I was a young 2LT at Fort Knox, KY, I bought gas on Post because it was way cheaper than in town. That gas was complete garbage. My car ran incredibly rough and it took a couple tanks of good gas before it was back to normal.

That was when I stopped buying cheap gas altogether. Makes me cringe when my mother drives by HEB and wants to get gas from there. It might be fine. But I'm never going to find out.

Most fuels are fungible products produced by various refineries/gasoline blenders. Top Tier gasoline has an additive that's supposed to limit buildup on engine components. Getting more/less MPG/performance is likely coincidental with quality variations (above minimum limits) to the upside.

Interesting experiment. I fall in the group that thinks there are just too many uncontrolled variables for your test results to really be anything more than interesting subjective conclusions.

Never track mileage that closely. Have noticed the computer number seems to be highly influenced by what happens in the first 50 miles of the tank. Fill up and drive on the highway looks much better than fill up and drive around town.

When my daughter had my hand me down g37 (NA 3.7 v6) at OU, I would notice a huge performance decline from either the quality of gas she was getting in Norman or the level she was willing to pay for and/or the fact that the upper level there is 91. It would drive incredibly rough and terrible and get noticeably and significantly better here in Dallas on any brand of 93 octane after a tank or two.

With my own cars, I can really only say that I have noticed performance differences from octane levels (Yes I know many say it doesn't matter,) especially but not exclusively in turbo engines. I drive a lot and all over town and fill up all over the place as needed rather than having a particular station I always go to. Honestly use RT and QT most often at the recommended octane for the car and have never really noticed any difference between stations.

I see Buc-ee's is not listed as top tier. My new QT is TT and both have ethanol free.

Yeah, too bad I can't get premium non-ethanol.

austinag1997 said:

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Yeah, too bad I can't get premium non-ethanol.

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Kind of hard to have a relative high octane rating if you remove the component that's largely used to boost the octane. Do you want to bring back tetraethyl lead or MTBE?

Sack up and run e85

Absolute said:

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Interesting experiment. I fall in the group that thinks there are just too many uncontrolled variables for your test results to really be anything more than interesting subjective conclusions.

Never track mileage that closely. Have noticed the computer number seems to be highly influenced by what happens in the first 50 miles of the tank. Fill up and drive on the highway looks much better than fill up and drive around town.

When my daughter had my hand me down g37 (NA 3.7 v6) at OU, I would notice a huge performance decline from either the quality of gas she was getting in Norman or the level she was willing to pay for and/or the fact that the upper level there is 91. It would drive incredibly rough and terrible and get noticeably and significantly better here in Dallas on any brand of 93 octane after a tank or two.

With my own cars, I can really only say that I have noticed performance differences from octane levels (Yes I know many say it doesn't matter,) especially but not exclusively in turbo engines. I drive a lot and all over town and fill up all over the place as needed rather than having a particular station I always go to. Honestly use RT and QT most often at the recommended octane for the car and have never really noticed any difference between stations.

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I tried to make it clear that I have not drawn ANY conclusions, only proposed questions or hypothesis if you prefer. Some of the points you bring up, as well as those brought up by others (octane, ethanol levels, etc.), are valid while others (driving style, highway/city, performance) really aren't since I worked hard to control for those things. You'll just have to take my word for performance for MY vehicle. Not sure why you wouldn't be willing to.

Again, not a study because, as mentioned, too many variables, but a question: is TT gas usage really a panacea or are there other, equally important, factors such as gas station gas turnover, octane, ethanol levels, and other things discussed here (and not brought up so far)? Can you duplicate the benefits of TT gas by your own additives (Redline/Techron/etc.)?

I think that one thing that can't hurt, regardless of whether you're brand agnostic or you stick to a TT label, is to go to the busiest station possible. Until I'm shown different numbers, I'm going to suggest that while my experiment here shouldn't lead to any conclusions, it should at least provide some evidence for that.

austinag1997 said:

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Yeah, too bad I can't get premium non-ethanol.

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A lot of QTs have 91 octane non ethanol

Absolutely did not mean to infer questioning any of your thoughts or conclusions. Sorry if i sounded like that. We, well car people, would absolutely feel minor differences in performance in our personal vehicles. Just meant that it is really more of a feel thing than scientific experiment.


Personally, I kind of doubt the TT part makes a huge difference as long as you are buying at a reputable station. RT and QT are big enough that they should be reliable. They are to me. Heck, I'll even use a Sam's or a Costco if I happen to be at one and need gas. Living in Dallas with that strategy, I have never had an issue or noticed a difference in my cars other than from octane. But I definitely avoid hole in the wall places


ETA:

I guess I do question the mileage part of the experiment. Even following a normal commute routine and trying to be consistent, there are too many variables to be sure about the small differences you noted, imo. But performance, absolutely you can judge that.


Either way, I did not mean to be rude about it.

The gas is all the same. It is the additives, or lack of additives, that make things different.

My Hemi will burn any and all of it and not really care. I could probably run it on my piss after a hard night of drinking and make it to work. If you buy the cheap stuff you have to buy a bottle of the cleaner stuff once in a while.

91AggieLawyer said:

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Absolute said:

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Interesting experiment. I fall in the group that thinks there are just too many uncontrolled variables for your test results to really be anything more than interesting subjective conclusions.

Never track mileage that closely. Have noticed the computer number seems to be highly influenced by what happens in the first 50 miles of the tank. Fill up and drive on the highway looks much better than fill up and drive around town.

When my daughter had my hand me down g37 (NA 3.7 v6) at OU, I would notice a huge performance decline from either the quality of gas she was getting in Norman or the level she was willing to pay for and/or the fact that the upper level there is 91. It would drive incredibly rough and terrible and get noticeably and significantly better here in Dallas on any brand of 93 octane after a tank or two.

With my own cars, I can really only say that I have noticed performance differences from octane levels (Yes I know many say it doesn't matter,) especially but not exclusively in turbo engines. I drive a lot and all over town and fill up all over the place as needed rather than having a particular station I always go to. Honestly use RT and QT most often at the recommended octane for the car and have never really noticed any difference between stations.

---

I tried to make it clear that I have not drawn ANY conclusions, only proposed questions or hypothesis if you prefer. Some of the points you bring up, as well as those brought up by others (octane, ethanol levels, etc.), are valid while others (driving style, highway/city, performance) really aren't since I worked hard to control for those things. You'll just have to take my word for performance for MY vehicle. Not sure why you wouldn't be willing to.

Again, not a study because, as mentioned, too many variables, but a question: is TT gas usage really a panacea or are there other, equally important, factors such as gas station gas turnover, octane, ethanol levels, and other things discussed here (and not brought up so far)? Can you duplicate the benefits of TT gas by your own additives (Redline/Techron/etc.)?

I think that one thing that can't hurt, regardless of whether you're brand agnostic or you stick to a TT label, is to go to the busiest station possible. Until I'm shown different numbers, I'm going to suggest that while my experiment here shouldn't lead to any conclusions, it should at least provide some evidence for that.

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I always try and buy gas from stations with high turnover. I think that makes a difference, not necessarily in mpg though.

Absolute said:

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Absolutely did not mean to infer questioning any of your thoughts or conclusions. Sorry if i sounded like that. We, well car people, would absolutely feel minor differences in performance in our personal vehicles. Just meant that it is really more of a feel thing than scientific experiment.


Personally, I kind of doubt the TT part makes a huge difference as long as you are buying at a reputable station. RT and QT are big enough that they should be reliable. They are to me. Heck, I'll even use a Sam's or a Costco if I happen to be at one and need gas. Living in Dallas with that strategy, I have never had an issue or noticed a difference in my cars other than from octane. But I definitely avoid hole in the wall places


ETA:

I guess I do question the mileage part of the experiment. Even following a normal commute routine and trying to be consistent, there are too many variables to be sure about the small differences you noted, imo. But performance, absolutely you can judge that.


Either way, I did not mean to be rude about it.

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You weren't rude about it.

Might be interesting to run a second experiment. Now that you determined the best performing, redo the mileage test for a few months with only that gas and see what spread you get in mpg.

Absolute said:

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Absolutely did not mean to infer questioning any of your thoughts or conclusions. Sorry if i sounded like that. We, well car people, would absolutely feel minor differences in performance in our personal vehicles. Just meant that it is really more of a feel thing than scientific experiment.


Personally, I kind of doubt the TT part makes a huge difference as long as you are buying at a reputable station. RT and QT are big enough that they should be reliable. They are to me. Heck, I'll even use a Sam's or a Costco if I happen to be at one and need gas. Living in Dallas with that strategy, I have never had an issue or noticed a difference in my cars other than from octane. But I definitely avoid hole in the wall places


ETA:

I guess I do question the mileage part of the experiment. Even following a normal commute routine and trying to be consistent, there are too many variables to be sure about the small differences you noted, imo. But performance, absolutely you can judge that.


Either way, I did not mean to be rude about it.

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You weren't rude and I WANTED you to question. I didn't mean to imply otherwise. I simply wanted to say that, given everything said, I was trying real hard to NOT come to any conclusions because of the limited nature of everything: ONE car, maybe 15-18 (relevant) fillups at most, stations in ONE general area, pretty much ONE octane level, etc. This was simply one record of many that would be required in any study -- many being at least 100 or so. Some might say a thousand or more. Fair enough.

I just wanted to ask the questions I asked (won't repeat them) and see what others' thoughts were. Given the studies that allegedly show TT gas being better for your car, I didn't understand the results I've been getting over the last few months.

To clarify the mileage part, for the most part, I usually fill up around the same miles driven -- usually within 20 or so -- just about every fillup. Out of the last, maybe 20, there have been a few variations. My trip to Houston being one. One week I didn't go anywhere other than near my house -- very low mileage on that tank. I tried to pretty much ignore those (i.e. drop highs and lows).

91AggieLawyer said:

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To clarify the mileage part, for the most part, I usually fill up around the same miles driven -- usually within 20 or so -- just about every fillup. Out of the last, maybe 20, there have been a few variations. My trip to Houston being one. One week I didn't go anywhere other than near my house -- very low mileage on that tank. I tried to pretty much ignore those (i.e. drop highs and lows).

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How much of the tank are you refilling for your tests?

Do you let it get halfway down, 1/8th, or wait until the low fuel light has been on for 30 miles?

HollywoodBQ said:

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91AggieLawyer said:

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To clarify the mileage part, for the most part, I usually fill up around the same miles driven -- usually within 20 or so -- just about every fillup. Out of the last, maybe 20, there have been a few variations. My trip to Houston being one. One week I didn't go anywhere other than near my house -- very low mileage on that tank. I tried to pretty much ignore those (i.e. drop highs and lows).

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How much of the tank are you refilling for your tests?

Do you let it get halfway down, 1/8th, or wait until the low fuel light has been on for 30 miles?

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I generally judge by mileage and when my light comes on, I'm aware that I need to be on the lookout. My current vehicle says it holds 18 gallons and I usually put in between 16.5 and 17.25. Rarely less unless I down under a half and have to go on the road the next day. That's about 1 in 8 or so fillups.

I ran out of gas in my old Tahoe because the salesman told me it had a bigger tank than it actually has. I thought I had a few more miles than I did. That was 30 years ago and I check these things out, but I don't immediately go at 1/8 like a lot of people. Not that there's anything wrong with that.

91AggieLawyer said:

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HollywoodBQ said:

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91AggieLawyer said:

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To clarify the mileage part, for the most part, I usually fill up around the same miles driven -- usually within 20 or so -- just about every fillup. Out of the last, maybe 20, there have been a few variations. My trip to Houston being one. One week I didn't go anywhere other than near my house -- very low mileage on that tank. I tried to pretty much ignore those (i.e. drop highs and lows).

---

How much of the tank are you refilling for your tests?

Do you let it get halfway down, 1/8th, or wait until the low fuel light has been on for 30 miles?

---

I generally judge by mileage and when my light comes on, I'm aware that I need to be on the lookout. My current vehicle says it holds 18 gallons and I usually put in between 16.5 and 17.25. Rarely less unless I down under a half and have to go on the road the next day. That's about 1 in 8 or so fillups.

I ran out of gas in my old Tahoe because the salesman told me it had a bigger tank than it actually has. I thought I had a few more miles than I did. That was 30 years ago and I check these things out, but I don't immediately go at 1/8 like a lot of people. Not that there's anything wrong with that.

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Funny, I've only run one car out of gas - back in 1994. In 2002 or so, I let the fuel in my Grand Cherokee get down to the level where it fried the fuel pump. Both of those sucked.

My 1999 Expedition, has a 30 gallon tank, gets about 13 mpg and even after running for 30 miles with the low fuel light on, I've never been able to put in more than 27 gallons.

I learned the hard way last year to not let my BMW even get down to the low fuel light. It didn't fry the fuel pump (like the Grand Cherokee) but, it did go into some sort of freakout mode that tripped a bunch of error messages and the car started acting funny.

On my 16th birthday on my way home from school, I coasted into the gas pump. Paid for one gallon with change left in the door pocket. Thankfully gas was less than a buck a gallon back then. Got me home.