Nope. All grades are mandated to have 10% ethanol. No variations unless it's being sold as eth0, or marine fuel.
Are Shell/Exxon better than other Top Tier gasolines?
- Thread starter mojoe
- Start date
It’s a requirement for all grades to be licensed. But they have a minimum requirement and it’s possible to exceed it for premium or mid. I’ve seen a hand added chart for Chevron for when automated equipment is unavailable. I think the max volume for one bottle of Techron was 400 gallons for premium, but 500 gallons for others. Obviously not the same kind sold in stores.
There’s little incentive to not have ethanol. It increases the octane rating.
The most common fuel sold in the US is “reformulated basestock for oxygenate blending”, which is maybe 85 AKI before standard blending with 10% fuel ethanol.
That's not a given depending on how that's achieved. Oxygenates (MTBE, ethanol, methanol) are typically the easiest and cheapest way to increase octane rating. But they have less energy. But it is possible to make higher octane fuel without it. I mean - 100% octane would 100 AKI. But that's not typically how the refining industry goes about making fuel. It's a lot less precise than that for economic reasons.
87 octane is mostly 10% ethanol these days made with a lower octane base fuel before ethanol blending. It has no more energy on average than 89/91/93 also including 10% ethanol.
Actually, no. The mandated amount of ethanol does not change when RVP season starts. Ethanol isn't refined, but produced, it's properties cannot be manipulated like the base gas can.
The key to lower RVP is the amount of butane included in the gasoline. All blends remain the same.
It's a complicated thing. As much as many like to believe from marketing, the detergent additive packages can be the same between different fuel marketers. There are off the shelf additive packages that meet EPA minimums and Top Tier requirements. Some are even the same, where the concentration would determine what standard it meets. In the following LAC stands for "lowest additive concentration" that would meet minimum regulatory requirements in the United States. So the same additive could be the generic one made available for anyone to use at the fuel depot or in a higher concentration for those trying to meet the Top Tier standard.
Recommended Dosage
HiTEC® 6590 is EPA, LAC Final Rule and TOP TIER certified. Please contact your Afton Chemical representative for specific recommendations.
All EPA registered certified detergent additives added to pump fuel in the US are on this list:
https://www3.epa.gov/otaq/fuels1/ffars/web-detrg.htm
The one thing you won't notice on the list is the names Shell or ExxonMobil. Also no Infineum, which the Shell/ExxonMobil joint venture that used to make one certified gasoline additive that was on a previous version of this list. So obviously Shell or XOM are buying additive from someone else. It could be something developed just for them or could conceivably be an off the shelf additive. But what's "proprietary" might not be the development of the additive, but the identity and the concentration used. There are other additives other than the detergent, so that might also be a factor in the overall quality of the fuel.
And the really weird thing is that many companies aren't afraid to sell to their competitors. Chevron Oronite additives aren't used in-house, so obviously they're being sold to other companies for retail gasoline.
Last edited:
I do remember when winter blends might actually have less ethanol to help improve volatility.
That would surprise me. I don't think engine management systems are that sophisticated. My wife's kia rio pinged so bad on 87 octane it set off a knock sensor. The engine didn't adjust to that and it was bad enough to trigger a cel. Had to switch to premium until we paid $180 for a software update.
I do. I just told you. I renewed a municipal fuel contract annually (30+ years) and read the contract language. The fuel companies bidding clearly state that they offer better discounts because of the higher percentage of ethanol. Have you read the disclaimer decal at the fuel dispenser? The law allows up to a particular percentage of ethanol. The cheap non-branded distributors want cheaper fuel. Hence, more ethanol.
It's actually CBOB. Conventional Blendstock for Oxygenate Blending. That stuff is 85 AKI and the 10% ethanol raised the octane to 87. RBOB is Reformulated Blendstock for Oxygenate Blending and is usually 90 AKI. This means less ethanol can be added to RBOB to produce a higher octane in areas that mandate a RFG (Reformulated Gasoline) for emission/smog reasons, ie; 91octane because ethanol raises the RVP (Reid Vapor Pressure). So to keep those numbers down, especially during summer months, refiners supply blendstocks with a slightly higher starting AKI so that less ethanol needs to be added to produce higher octane fuel. It is cheaper for the refiner to make a higher AKI BOB for premium fuel, as the additional components to manage RVP are more expensive than the components are for a higher octane starting blendstock. CBOB already contains a sufficient lower amount of components to keep RVP in check with 10% ethanol (and can go lower with up to 15% ethanol) without the additional cost involved in using components at higher rates with a higher octane finished fuel to manage RVP. This is why sometimes there can be as little as 5% ethanol in premium fuels. I have used an ethanol tester at several of the stations near me and have measured ethanol in premium fuel as little as 3%. So while it can be UP TO 10%, sometimes it isn't in premium fuels depending on the market the fuel is sold in.
Edit: there is also a lower 85 AKI RBOB for markets that require the reformulated fuel components for emission/smog mandates while making a lower 87 octane finished fuel.
Last edited:
Exactly. Ethanol raises RVP, however in colder weather it won't volatize as well with liquid fuel at a colder temp. Butane is a much better component added to increase volatility during colder months. Since butane can also increase octane, less ethanol needs to be used to get a specific octane number.
Last edited:
Depends on the system. Most flex fuel engine management should be able to handle a wide range.
Read the pump more closely. Its UP TO 10%. It can be less than 10%
Ethanol does have certain benefits in cold weather though. I know a lot of people think they need gas line antifreeze, which is just an alcohol to prevent water freezing in cold weather. I believe it is miscible with any water that gets in the fuel and also allows it to mix with the gasoline.
Plus its cheap. Well, as long as the corn industry is propped up with big subsidies by folks like ADM
.
Plus its cheap. Well, as long as the corn industry is propped up with big subsidies by folks like ADM
There are no more subsidies per se. But there are renewable fuels mandates that bring up the demand. The cost of ethanol is likely to be less than gasoline per unit volume, so there's an incentive use it just based on costs (and the antiknock properties).
I do understand that the oil companies preferred MTBE because they made it themselves and could transport it via existing pipelines without causing corrosion as ethanol will.
4WD
$50 site donor 2025
Yep, the “recipe” comes from their RE group - but could contain chemicals from BASF among others …
Hugher octane fuel emits less heat when ignited, hence - burns cooler.
No subsidies out in the open as they were before. Now the money flows behind those mandates initiated by the corn lobby. Ethanol works, not very well, but everyone gets paid.
Similar threads
