Probably more a question for the performance guys on here but I'd be interested in all opinions.

Does premium fuel actually make a difference for the (approx) 10p a litre price increase? I've read quite a few pages on the internet with arguments for and against but nothing to actually 'prove' a performance increase.

I read in a Ford manual that the recommended RON or octane level for a new 2.0 petrol Mondeo is 87. In the UK I believe standard unleaded is 95 RON and Super unleaded is 98 RON. Surely standard fuel is already much higher than the minimum so I wonder if there is a useable difference in paying for premium. Most of the big suppliers will say their premium fuel has better quality detergents to keep injectors clean, but 10p a litre is quite a price to pay.

Ford Mondeo Owners Manual:

"We recommend regular unleaded gasoline with a pump octane rating of 87. Some stations offer fuels posted as regular with an octane rating below 87, particularly in high altitude areas. We do not recommend fuels with an octane rating below 87. Premium unleaded gasoline will provide improved performance and is recommended for severe duty usage, for example a fully loaded vehicle."

Extract from www.petrol-prices.co.uk:

In the UK, the most common petrol types are:

• Ordinary unleaded – 95 RON
• Super unleaded – 98 RON

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If your car can make use of the extra octane rating then go for it, if not the money is wasted.

My ST is tuned for performance fuels (as stated on a label inside the filler flap) so that's what it gets.

Chemically speaking, premium fuels should make a difference - whether that's worth 10ppl is very much down to the individual paying for it - to me it is worth the benefit

The ST brochure for Germany actually states that you must use 97/98 RON petrol to achieve the stated 250PS figure.

I don't use anything other than standard 95 RON from the big 4 in my 1.5 ecoboost, but I fully intend to use 97/98 RON in my ST :D

I admit I have used premium diesel in my ST since having the engine replaced. Worst case I've used regular diesel from a known dealer...not supermarket stuff.

The reason for my question is I am pondering what to use in my next car. Technically the engine is the Focus ST one, although slightly less tuned.

The 2.0 petrol Mondeo must be the same ecoboost as the ST Focus, what is it's power rating?

Yep. It is but Mondeo is (only) 240ps. Mu Ha HAAA

Remember it's not only possible performance gains that matter - higher quality fuel with added detergents burns better which helps keep the injectors & other engine components cleaner - especially in diesels

You should find the Mondeo can achieve its performance target of 240PS on 95 RON, but as Mark says, there are other benefits than just performance.

The ECU should also adjust for a slightly better compression ratio as the fuel is more resistant to knocking, which is where the MPG claims come from. Unless you just press the loud pedal more because you have go faster fuel :D

Now I'm swaying towards the premium fuel again. Keeping the engine in good condition is a priority for me. Plus with the amount of miles I do (less than 9k a year) the few extra quid at fill-up time is probably worth the piece of mind.

Thanks guys for your input.

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I have always ran my ST on premium fuel. But I have also had diesel cars while I have owned the ST which I just run on regular diesel.

Lots of people that have ran their car on regular fuel and then change to a premium fuel expect to see changes instantly, but that's not the case.

Tesco's Momentum is 99 RON, same RON as Shell's V Power

Tesco's Momentum is 99 RON, same RON as Shell's V Power

Aye, My car likes that. :d

My ST too :)

I use shell v power most of the time but if I'm doing a long motorway run that's just going to empty the tank I put in standard shell to save a few quid then refill with v power. I've never put supermarket fuel in the ST

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Thing is there's no such thing as '' supermarket fuel '' - only fuel sold in supermarkets which comes from the same few refineries & distribution depots as all other fuel in the U.K.

It meets the same BS ratings & RON standards as all other fuel retailed in major service stations

Doesn't have the same additives though.

Ive only had one of my cars on a rolling road and that was an Astra VXR which was unmodified and put out 3bhp over the quoted standard 240bhp using regular Asda fuel.

Only the premium fuels such as V power & Optimax etc have additives , I believe Tesco's 99 RON Momentum has additive too - hence the premium price

the additives make a massive difference.

If I stick any supermarket fuel in, the car gets louder, more knocky, and under-powered. It might be delivered from the same refinery, but I never believe the fuels are the same. They just cannot be! I don't care if the additives are added at the pump, or before hand, but knowing my car and trialing different fuels, they all behave differently. :p

My Haynes manual says its not worth it!

Tescos makes the car sound even more like a tractor, sainsburys is a bit hit and miss i tend to go for Shell with 200ml of 2 stroke each tank, then at least once a month go for v power and usually 100miles before the MOT i go all out with vpower and some diesel injector cleaner.

With the oil i think i lose a little kick, but it evens out and is nice and relitively smooth, certainly quieter.

interestingly ive noticed that at the end of the tank in hte last 100 miles or so it gets noisy regardless of what fuel i use, starting to wonder if the tank is needing cleaned out