Super unleaded RON rating

Joined
Aug 26, 2009
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314
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UK
This is more of a curiosity.
Over here we have standards /regulation for RON rating: regular: 95RON and super 97/98 RON.

95 equates to US 91 (ROM/AKI??) and 97/98 to 93.

I do not understand why the standard for super is 97/98 and not one or the other!

when it comes to regular (also called premium) all retailers label their product as 95 but..
When it comes to super, ignoring the sexy names they like to use the RON can varry between 97 & 99 (there was a time BP sold a RON of 102!!). Currently Shell & Esso label theirs as 99RON.

So do they all buy the same base stock (97/98) and then put additives & octane booster to pump it up to 99 or they use a higher RON base stock.

They all claim they use additives in ther super unleaded for cleaning, lubrication etc but no mention of octane boosting.

I have been without luck getting any clarity on this for the retailers. MAybe a member with deeper knowledge / info can shine a light on this:)
 
Joined
Nov 11, 2018
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The grades in the states are also all over the place… regular is 85 in some areas (generally high altitude) and 87 in others, while premium ranges from 91 to 93 for far less clear reasons (usually emissions related but that gets murky).

But no, the base gas is whatever octane they select. 93 would not be 87+octane booster and additives, it’s 93+additives only. Additives are injected as the fuel is loaded into the truck. GoldDot40 did a Q&A thread, granted it pertains to the states, it’s a good read.

 
Joined
Sep 19, 2008
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Pennsylvania
US octane numbers are an average of research octane number (RON) and motor octane number (MON). The first is determined in a lab under carefully controlled conditions and the second under real world load conditions. Almost all Top Tier stations on the east coast seem to have a 93 rating by this system. However, I have com across some other stations where the highest octane is 91 or 92. Are they blending at the pump to save some money? Their prices often show the same cost differential between regular and high test as Top Tier stations.
 
Joined
Nov 11, 2018
Messages
5,668
Location
Great Lakes
US octane numbers are an average of research octane number (RON) and motor octane number (MON). The first is determined in a lab under carefully controlled conditions and the second under real world load conditions. Almost all Top Tier stations on the east coast seem to have a 93 rating by this system. However, I have com across some other stations where the highest octane is 91 or 92. Are they blending at the pump to save some money? Their prices often show the same cost differential between regular and high test as Top Tier stations.
Both MON and RON are tested under laboratory conditions. MON is tested at 900rpm with preheated fuel and variable ignition timing, RON is tested at 600 with a variable compression ratio.
 

bonjo

Thread starter
Joined
Aug 26, 2009
Messages
314
Location
UK
I am aware of the geopraphical as well seasonal variation of fuel.

What I am curious about is how as an example esso & shell achieve the claim of 99 RON (over here, 93 inn the us?) for their supreme and vpower fuels.
Do they use 99RON base stock or do they add octane booster?
 
Joined
Nov 11, 2018
Messages
5,668
Location
Great Lakes
I am aware of the geopraphical as well seasonal variation of fuel.

What I am curious about is how as an example esso & shell achieve the claim of 99 RON (over here, 93 inn the us?) for their supreme and vpower fuels.
Do they use 99RON base stock or do they add octane booster?
No, there is no “octane booster” added. The refinery producing the fuel blends various base stocks together to get a target octane rating, then ship that to a terminal for trucks to pick up and deliver to a station.
 

bonjo

Thread starter
Joined
Aug 26, 2009
Messages
314
Location
UK
thanks skippy for info.
out of the 4 retailers I contacted, only shell responded but initially with totally unrelated and stupid quotes from their marketting. I asked for the wuery to be escalated to a "competant" advisor.
As a coincidence, today I received a much more helpful reply from shell (which tallies with your info; here are sections of their reply to my questions:

"Shell V-Power Unleaded is formulated with a higher octane quality of 99 RON compared to 95 RON for Shell FuelSave/Shell Regular Unleaded in the UK"

"In the case of Shell V-Power Unleaded 99 RON the higher octane is achieved by a different base stock grade and not additive."

My curiosity is satisfied (for now!)
 
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