Subaru Ascent Forum banner

Regular or Premium

144K views 347 replies 81 participants last post by  hokiefyd 
always go with has been recommended because rarely will you ever find that there will be any noticeable gain in power or even fuel economy. Its only when you go for really high octane fuel on a tuned engine that real changes happen.
While I agree I still wonder if there is any difference between regular and premium. The Mazda CX9 shows different power numbers depending on the fuel and I wonder if the Ascent would do the same thing.
 
Tired of paying probably close to 30 dollars a month more for gas. I'd rather roll that savings into the car payment or something.
Well my current vehicle only gets a 18MPG highway and 12MPG city on regular so no matter what I put in it will be a large savings.


Also I would only use premium when I plan on loading up the car for a long trip. A little more power can be nice when going up a large incline on a highway in a fully loaded vehicle!:grin:
 
Yah what is going on? Just summer time price hikes?
If you look at supply and demand right now the demand is outstripping the supply and the excess that was stored from oversupply is starting to drop. I don't think it will keep going up as at some point the shale fracking will pick back up as the price hits the necessary point to be profitable.


At least this is my opinion.
 
Can’t find ethanol free near me so my option is 87 Costco or 93 Costco. Or another brand.

Apparently the person that runs the fuel division for Costco is going to call me to talk about my concerns on top tier and the carbon buildup. Anyone want me to ask something special? Again he is Costco fuel, not Subaru, so he can’t comment specifically on the FA24.

The big question I have is if the 93 will actually harm the exhaust system of the Ascent. My gut says no, but someone on another forum said that since 93 burns slower it actually ends up with more unburned fuel getting into the exhaust system which is problems for the catalytic converter?
Costco has some of the best fuel and a lot of detergents. You should be fine with Costco 87. In fact I'm waiting for the Costco to open across the street from my office. They just pushed back the opening to September and I'm shocked with how quickly the building is going up.
 
This really makes little sense to me. The base gasoline is a commodity from a limited number of refineries, the differences would only be the additive package that each brand adds and that should have no major short-term effect on gas mileage given that the octane ratings for each brand were accurate and equal. Maybe they're not. It would take several tanks of each brand to accurately discern any difference, and then you would also need to do it in a controlled manner to rule out differences in driving.

Also, the time of year and where you live can make a difference. In colder regions, a winter blend may often give less effective gas mileage than the summer blend due to a change in the Reid Vapor Pressure (RVP) of the fuel. This is done at the refineries, however, so again there should not be a lot of difference between gas stations.

To claim one brand gives better gas mileage over another without controlled testing would only be conjecture.
Those additives can make a large difference which is why I use only Top Tier gas. I had pinging with my old vehicle when filling up at Wawa and Royal Farms a lot but it would stop right away when filling up at BP, Shell, or Exxon.

I plan to fill up primarily at Shell, Exxon, and Costco with the Ascent as I don't wish to have any issues in the future.

Premium shouldn't hurt the vehicle but with the price difference being 50-60 cents per gallon I don't feel it is worth the extra cost. Granted with gas prices dropping it might be in the future!
 
You're missing my point entirely, taking it out of context, and going back to generalities which are too broad for claiming one brand can offer better gas mileage than another. Such broad generalities don't advance the specific topic I was addressing, which is gas mileage differences between brands.

Since base gasoline is a known common commodity, differences between brands is primarily the additive package. These packages supply octane modifiers, detergents, corrosion inhibitors, antioxidants, and oxygenates which are carefully controlled by all brands, especially the Top Tier brands. The octane rating must meet specific national standards to be rated at a specific number, so if one brand is rated at 92 octane, it should be more or less equivalent in octane to another brand rated the same. So that negates that specific factor which could affect gas mileage. Additionally, unless a specific brand claims that they do not add 10% ethanol (E10), which lowers the energy of fuel, that gas mileage factor too can be negated.

The rest of the additives should not, in the short term, provide significant gas mileage differences between brands. If they could, and one brand had a proven, exclusive, significant advantage over another, believe me they would advertise it profusely. In the long term additives might make a difference if say the one with more detergents kept your engine significantly cleaner. But for someone to accurately claim that they got noticeably better gas mileage from one tank of a specific brand over another is simply conjecture because the factors that would give gasoline significantly more energy from brand to brand is very small, and it would take far more accurate, long term, and controlled testing to conclusively prove any differences.

This is why I find it very hard to believe anyone who states offhand that they get better gas mileage from brand ABC than XYZ. Until an accurate, well controlled test done by an accredited source become available, don't believe such claims. The only generalization that can be reasonably accurately stated is that Top Tier gasoline is probably better to use because the additive package must meet specific standards to claim a Top Tier rating.
I did not mention MPG I was merely stating that those additives are important and do play a role long term and can in the short term if you have been using non additive fuel for a while.

My only argument is it is worth paying the few cents per gallon more for the cleaning agents from the Top Tier gas companies. There are 3rd parties backing this up not just my one time experience.
 

No, but you quoted my post which was specific to MPG. If you didn't, I would not have responded to your post as we both agree that Top Tier gasoline should be use.
Sorry I think it was because I was agreeing with you!:tango_face_wink:
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top