Viewing a single comment thread. View all comments

henry_sqared t1_iu5ze40 wrote

Unaffiliated stations are allowed to bid daily on fuel and are not locked into prices negotiated by major brands. This can work for or against them (and runs a greater risk of not getting any fuel if supplies are constrained), but usually results in better prices.

38

pixel_of_moral_decay t1_iu615bd wrote

This is all true.

Also:

They tend to (but not always) use the minimal detergent requirements under the law. So more buildup in your engine. Vs a “Top Tier” gas, which is what your owners manual will recommend you use.

All gas is the same (there’s laws on this). The additive package they add to the fuel can vary slightly as long as it at least meets a minimum standard.

There’s some evidence this is actually a material difference:

https://www.consumerreports.org/fuel-economy-efficiency/top-tier-gasoline-worth-the-extra-price-a7682471234/

Lastly, gas is intentionally sold slightly cheaper to unaffiliated stations to keep them afloat. They are the primary defense against anticompetitive claims. Gas companies can say “well look at their price”. That’s a really cheap insurance policy to keep US courts off their backs.

20

objectimpermanence t1_iu6kzc0 wrote

> They tend to (but not always) use the minimal detergent requirements under the law. So more buildup in your engine. Vs a “Top Tier” gas, which is what your owners manual will recommend you use.

It’s interesting because that’s potential a problem for newer cars with direct injection that most people probably are unaware of. Not that most people know whether their engine has direct injection and/or port injection to begin with.

That said, my parents had a direct injected car that they religiously filled only with premium Shell or Chevron gasoline and it still ended up needing an expensive repair to clean the carbon buildup on the intake valves after about 100k miles.

Apparently, the design of some engines makes them inherently prone to carbon buildup no matter what type of gas you use.

6

pixel_of_moral_decay t1_iu6nk77 wrote

The manual for every major car manufacturer strongly recommends top tier fuel.

As I understand it, it’s just a higher standard of detergents in the additive package beyond the federal standard. It’s otherwise the same fuel.

And yea, DFI is going to be more impacted since traditionally fuel is sprayed so it cleans the engine. DFI kinda prevents that effect.

I don’t think premium fuel would have any difference regarding detergent additives. That purely comes down to the additive package. Premium fuel is just a higher octane.

The article I linked to above shows some of the results from the AAA study. It’s pretty interesting.

Since reading that, I try to stick with Top Tier when possible, which 9/10 times is no real effort since it’s most stations. It’s not like I’m really making a serious effort.

3

objectimpermanence t1_iu6t57e wrote

Yeah they used premium only because that’s what the manual said and the car’s gas cap was labeled “premium fuel only.”

But Shell’s premium grade also has extra additives (“V-Power”) beyond what their regular and middle grades have.

At most other brands, the premium grade has the same additives as the brand’s other grades.

3