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this post was submitted on 13 Oct 2023
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Can you cite any evidence that lower tier gas gives worse MPG?
Lower octane gas definitely gives you less power. The owner's manual for my car gives two different horsepower ratings for different octane gasoline.
Probably a forced induction engine. Normal NA it makes no difference as long as it's not a high compression engine. Octane rating is how much heat and pressure the gas can handle before auto igniting. So higher octane means an engine with a turbo can run higher boost on higher octane which makes more power. It's a waste of money for most people to buy more expensive fuel. Though some fuel can be just shit and full of water at those sketchy stations.
Exactly. I tried top tier gas (91 octane) and noticed no difference in gas mileage. I live at high elevation and have the option of 85 octane and do notice the engine rides a little rougher than with 87, but fuel economy is pretty much the same (like within 2%?).
Just get whatever your car's manual states. Some cars need higher octane, most don't.
You guys are confusing top tier gas vs higher octane. Or this thread has just been interchanging them and not being consistent. Two terms are being used. Top tiered as name brand vs higher octane. Both discussions are happening at the same time.
I mean the octane tiers at the pump, or what is usually marketed as regular, premium, etc. There are at least two other terms used to describe gas tiers:
AFAIK, all three terms are independent of each other, so you can have tier 3 gas with or without detergents, in any octane tier you need.
I agree but in this thread people are interchanging high octane vs top tier.
Fair. Thanks for the correction, I'll try to be more precise going forward.
It isn't just you, I was more throwing this out there in general. I posted in another part of the thread too.
That sounds right, my car is a turbo charged 4 cylinder. TIL, thank you!
It can still be optional to run higher octane. Older Volvo 5 cylinders could run 87 with no problem because they only ran 9lbs of boost (only certain models). Most modern turboed engines usually can optionally run more boost if you put in higher octane. The issue is they rely on detection of early detonation when running worse fuel. Which scares me because of it fails engine goes boom very fast.
Use the octane that is recommended for your vehicle.
Lower octane is not lower tiered. Lower tiered is buying gas at Kroger or Costco vs Shell
Ironically Costco is a certified Top Tier brand.
https://www.toptiergas.com/gasoline-brands/
That's interesting to know.
Project Farm did a scientific comparison and while the higher octane fuel does give a bit more power and efficiency it doesn't generally result in much difference. Like less than 5%.
https://www.consumerreports.org/cars/fuel-economy-efficiency/top-tier-gas-is-better-for-your-car-and-might-be-among-the-c-a9639508891/
That article is talking about the quality of gas and not regular vs premium. Quality is very important and "top tier" is a rating that sets a minimum quantity of detergents and max water content. So it's good to try and find that top tier sticker on the pump but it's still marketing. Top tier is a company AFAIK that sells the label after verifying the gas meets their requirements. All gas comes from the same place in your area so the top tier thing is even more questionable.
Also that article mentioned regular vs premium and says not to bother using premium if your vehicle doesn't require it.
Top Tier is about detergent pack, not about regular versus premium, so I'm not sure why you bring that up. Top Tier requires 2x the EPA mandated minimum detergent.
Oh shoot thought you replied to my comment, can't trace lines well I guess.
I was looking into it a bit and the whole thing seems scummy. Yes it sets requirements that are hand wavey good for your engine. But it also seems to force gas stations into using only a handful of vendors so they get that sticker. It's endorsed by the big automakers but they also endorse the regular fuel standards. I wonder who is paying top tier LLC for the sticker and all their marketing?
The stations that carry it tend to only carry one brand to begin with. The owner of that brand is generally the one that pays, as they have to submit for testing at their own expense.
It's not always more expensive. All Costco gas is Top Tier, for instance.
They require the brand to use the 2x detergent level for every grade, at every location, to display the Top Tier logo.
I go through a tank of gas every 1-2 days. When I don't fill with Top Tier, my fuel economy goes down on that tank. When I consistently don't fill with Top Tier, my fuel economy goes down even on my next tank of Top Tier. That's when it's time to throw in a bottle of polyetheramine (Techron, Redline, Gumout Regane, etc.) to clean things up.
DI engines unfortunately require deeper, periodic cleaning, as the additive will not reach the valves. But I do not have a DI engine, so the detergent makes a significant difference.
It particularly makes a difference in how often I have to (or do not have to) replace lifters to keep them in spec. This engine has solid, non-adjustable lifters.