Let's Debate: Do You Splurge On Premium Or Stick With Regular Gas?

Illustration for article titled Let's Debate: Do You Splurge On Premium Or Stick With Regular Gas?
Photo: Joe Raedle (Getty Images)

I am currently standing in the neutral zone of a raging debate that involves both my husband and my boss at A Girls Guide to Cars, Scotty Reiss. It pertains to the age-old question: is it worth the money to fill up your tank with premium gas, or is regular going to do the trick?

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I have never regularly driven a car that would really benefit from premium gas, but when I was doing my overnight drives from Philadelphia to Toronto to visit my then-boyfriend (now my husband) Chris, he was adamant that I fill my Mazda 2 up with premium gas. I am usually just going to stick with whatever is cheapest, but he kept telling me that premium was the way to go.

So, on one of my trips home, Chris filled my tank with premium and told me to see what would happen. I was under the impression that I was able to travel farther before I needed to fill up, but in retrospect, that is possibly because he also topped up my tank, which I never do. Anyway, I was impressed enough to just take him at his word because I am too lazy to actually do a proper experiment where I calculate the mileage I travel with different kinds of gas.

But I was recently talking to my boss Scotty about how expensive it is to fill up the gas tank on my ‘96 Suburban, and she was like, “bro why are you even bothering with premium” (except she did not call me ‘bro’ because Scotty is a real adult, unlike me). She enlightened me on the fact that some cars are designed to run at a higher octane and that some cars will get a nice horsepower boost from a premium fuel, but for something like my Mazda or my Suburban, it probably didn’t matter.

My husband, on the other hand, is telling me that I should definitely be using premium in the Suburban because it’s an older, heavier car with a big engine. A running joke between the two of us is that every problem can be solved if you just spend more money, and that’s kind of where I’m falling on this debate. Why not just spend more for the higher-octane gas if it’s not going to cause any harm? At the same time, I’m now facing triple-digit bills at the gas station for the first time with the Suburban, which is a concept that makes me cringe because it cuts into my “buying dumb shit on eBay after I’ve had a glass of wine” budget.

As with most of my conundrums, I am going to outsource further opinions in order to justify my own. Where do you fine folks stand on the octane question? 

Weekends at Jalopnik. Managing editor at A Girl's Guide to Cars. Lead IndyCar writer and assistant editor at Frontstretch. Novelist. Motorsport fanatic.

DISCUSSION

hammerheadfistpunch
HammerheadFistpunch

Look the simple story here is that octane rating is a means to prevent pre-ignition. Any car with OBDII will tell you if you are doing it wrong because it will have knock sensors to detect pre-ignition. The best tuning you can hope for is as much timing advance as you can get before pre-ignition. Thats the point of the knock sensor, the fuel map dictates a base performance and then the computer retards or advances timing based on a number of variables including knock. The long and skinny of it is this: if you aren’t knocking, which 9 times out of ten is not subtle, or you aren’t throwing a code, then the knock resistance of the fuel is adequate.

Sometimes the engine will pull timing to use a lesser grade fuel and run without knock and while that’s less ideal, it’s still 100% fine. Think Ecoboost or other tuned engines where you can run regular but you get “best performance” or a different power rating with premium.

Case in point the GX470 has the exact same 2UZ-FE as any other Toyota with the 4.7 liter V8 (Tundra, 4runner, land cruiser, etc) but in the Lexus it requires 91. It’s 100% mechanically identical to the V8 4runner that requires 87, except in the lexus they added some timing advance in the mapping to boost midrange 15 lbs-ft and 3 hp. Guess what happens when you put 87 in it? It becomes a 4runner engine and the timing is pulled back to base map levels. Put in premium and get the advanced timing map. It’s the “premium” experience Lexus buyers demand or something.

On the other side of the coin, if you are pulling a trailer through Utah in the summer with an ecoboost F150 and you are filling it up with 85...your car is going to let you know about it.

TLDR: if you don’t hear knock and your car isn’t telling you it doesn’t like the fuel you chose...it’s very probably a perfectly safe octane rating.  Anything above that point is wasted money unless you know that your tune can adjust up and you want or need the higher tune.