I wanted to create a thread where we can share our views on fuel equivalents in the UK. It’s been a bit confusing for me with different fuel types at different petrol stations.
Please note that the information I gathered is specifically for V8’s (LS3 and L99); so someone with a V6 might want to add additional comments about their experiences for fuel on V6’s.
Before getting my car, I was doing some research on the difference between gasoline in the US and petrol in the UK. Most people were saying it’s exactly the same, it’s just a different word, tomato, tom-ay-toe. Personally I didn’t believe that fuel would be exactly the same, I did some digging, and it’s not.
All information I’ve seen so far points towards the V8’s being designed to run on US 93 (Premium) octane gasoline. The GM manual states that that 93 octane gasoline should be used as lower grade fuels can cause engine knocking. I hired a 2014 V8 SS whilst I was in Florida last year and they told me at the counter to only use “Super Premium Unleaded” where available. In most states the maximum you can get is 93, so this is what I went with.
This got me thinking so I took some photos of the fuel pumps so I could gather as much info as possible. (See photos).
You can just make out at the bottom, it says “(R+M)/2 Method”.
So the million dollar question is “93”, “93 what?” – How is it rated or measured differently?
According to WikiPedia the “(R+M)/2 Method” means that the octane rating is measured in “AKI” also known as “(R+M)/2″. Therefore the AKI rating would translate to a different RON rating for the purpose of converting to a UK fuel.
According to Wiki page http://en.wikipedia.org/wiki/Octane_…28R.2BM.29.2F2
the US (Regular) 87-AKI equates to UK 92-RON, US (Mid-grade) 89-AKI equates to less than UK 95-RON, and the US (Super Premium) 93-AKI equates to UK-97 RON. There’s also a table which shows an equivalent RON value of 97 RON for fuel outside of the USA and Canada.
This could mean that UK Shell V-Power 99-RON and UK Tesco Momentum 99-RON is way too high for our cars, but I’m no expert, I’m just repeating what I’ve read. It’s clearly not measured like for like as most people think.
I intend to keep this car for a long time so I wanted to make sure I was choosing the correct fuel for my LS3 engine. The petrol stations near me only do (Regular) 95 RON or (Super) 99 RON.
I did recently come across a Sainsburys Petrol station selling 97-ROM Super Unleaded so that’s what I’m going to stick to from now on. There’s a BP not too far from me that does 97-RON but BP are generally more expensive. Not all BP’s are the same though, I guess some are franchised and some are not.
For you V8 guys using 95 RON, it’s still going to equate to 90-91 AKI; which is still much better than the US mid-grade gasoline. Hope this information helps and please correct me if I’ve missed anything.