I've done a search but can't find anything on this

what Ron is recommended for the F-Type V6 S

UK has 95 as the base fuel and 97 and higher (called super unleaded) also available

 

There should be a sticker on the inside of the fuel door. In the colonies the sticker on my V8S says minimum 91 which here is the lowest grade of premium. I always use 93 since it is available at Costco.

 

The US uses an octane rating system (R+M/2) different from the UK (RON).

95 RON is roughly equivalent to US 91 octane. 98 RON is roughly equivalent to US 93.

Conversion chart in the link below.

Octane rating conversions - PencilGeek's BMW Blog

 

Interesting that it can use the base fuel - my current car (Nissan 370 Z) MUST use the premium 93 in US, and 97 in UK

 

+1

Many people are unaware of the different rating systems. As to why North America changed over to the present AKI (anti-knock index) system in the mid '70s and nobody else is not quite clear.

Forget the names attached to fuel- super, premium, ultra, etc. The only measure of resistance to detonation is the RON or AKI index number.

AFAIK, all modern Jags have 91 AKI or 95 RON as a recommended octane level.

 

In many cars, the ECU can compensate for lower octane fuel to some extent. You're probably making a little less power w/ 91 vs. 93 (95 vs. 98 RON), but it's a relatively small difference.

 

93 or higher is not at all common in North America. Most places are capped at 91.

Are you sure the US version requires 93?

 

It's more of a regional thing. In CA and much of the west coast, 93 is hard to find. In the US east of the Mississippi, 93 is available almost everywhere. Because of this, every car I'm aware of specifies no higher than 91.

I don't know why.

 

nope - not sure at all - I can only vouch for UK - the engine is designed for the higher rating, but does have a knock sensor so can run on the lesser fuel - the advice is don't push it much beyond 3000revs if you are

 

Pretty much all modern cars have such sensors. Seems the N.Am cars are tuned for 91AKI

87 octane fuel in the Z - Nissan 370Z Forum

Note the anecdotal stories of running consistently on lower grades.

 

indeed - pre-detonation corruption in the cylinders

 

There's no such thing as 'pre-detonation'. It's 'detonation' or 'pre-ignition'. Very different phenomena.

I was referring to the individuals who have consistently used lower than 91 fuel and suffered no ill effect. There is only speculation and theory as to what might happen from others, but no evidence to back it up.

Virtually every car or bike discussion board has the same argument- I've yet to see any cases of unmodified cars driven on the street suffering bona fide damage from use of low octane fuel.

Flame suit on.

 

You may need to switch to your pre-detonation suit.

 

"The Motor Octane Number (MON) simulates more severe operation that might be incurred at high speed or high load."

 

(R+M)/2

 

Yes, teacher, neglected to put parens within my parens ((R+M)/2).

 

Most of this has been said above , but in a very circular way.

From a guy that used to formulate gasoline (me):

RON=Research Octane(=R)
MON=Motor Octane(=M)
(R+M)/2=AKI(=posted pump octane in US)
Research Octane is tested under high rpm conditions per ASTM methods
Motor Octane is tested under high torque/load conditions per ASTM

In addition to engine design, octane requirement is based on a number of environmental conditions: temperature, altitude, humidity, barometric pressure. (for example, most SNL available in CO is only 89 (r+m)/2).

The F-Type does not progressively adjust for varying grades of fuel. It has two distinct sets of ignition and A/F maps (just discovered this over the past few days). It uses the high performance maps when the engine conditions suggest octane in excess of 91(AKI) and a de-tuned map that is (maybe) safely used down to 87 AKI.

Therefore, unless you have been doing some silly tuning requiring excessive octane numbers, using octane much in excess of 91 is a waste of money. And never use less than 87 octane (and in that event, drive gently). These 2 numbers (91 & 87) are cited in the owners manual.

 

Great post. Thank you.

 

oops ............ excuse my malapropism

 

I didn't know the difference between detonation and pre-ignition, so I found this. Pretty interesting.
Engine Basics: Detonation and Pre-Ignition by Allen W. Cline