That’s interesting? A Benefit of premium fuel then?
Barrie
I suppose if your 5 is a daily driver, then the extra cost of premium fuel could well be a serious consideration, especially if you are happy with running it on standard juice. If though, like mine, it is a second car, a sunny-day fun car if you like, then the extra cost is probably not really that important.
My current 5 seems to run more smoothly on the Sainsbury’s Premium that I generally use - it also feels more zippy, and if I can train my brain to not be as heavy on the throttle, I can definitely get a few more miles-per-gallon out of it. But with the low mileage I actually do in it, mpg is not a big consideration for me.
I’ve tried Shell V-Power, but I did not notice any improvement over the Sainsbury’s Premium, and as I have to take an 18 mile round trip to get it, I don’t consider it worth it, when Sainsbury’s is practically just around the corner.
Each to his own as they say !
Another Sainsbury premium user here. Again, not a daily driver so the extra cost doesn’t factor into my running costs.
Horses for courses!
I have two cars (not our MX-5) with identical, one litre, three cylinder engines. One runs very happily on 95 RON, the other definitely needs 97 RON or higher if I can find it.
The difference is that the second one has a supercharger and produces almost 50% more power and much more torque, at the same compression ratio. I’ve had to put 95 in it on a couple of occasions and it pinked, even at low boost.
The main reason for higher octane rating is to prevent pinking (detonation); the various blends may produce other benefits, such as lower emissions (and a cleaner engine) but it’s difficult for the average user to know.
[quote=jetmech]
Thanks for the info Ian, I totally agree that they should display the ethanol content at the pump, it’s almost a safety issue on older vehicles.
[/quote]
Some people maintain the ethanol problem is overstated but my own experience suggest otherwise. I have a 1972 Norton Commando which had a fibreglass petrol tank. It was fine for 30+ years until ethanol came along and started to attack the interior of the tank. I ended up having to replace it at great expense with a steel tank. We currently have 5% ethanol in petrol but they are supposed to be increasing it to 10% at some stage. I just hope they will be forced to label the pumps properly then.
Ian
I ‘seem’ to get better MPG out of premium but not sure if he cost difference cancels it out.
I get better mpg to the point that the premium stuff is cheaper, only just, but definitely cheaper.
I get slightly better mpg with the V-Power on any car, even new ones but especially with old ones. This is not always enough to equalise the pence/mile figures on the modern cars, but definitely is beneficial on older ones (20th century designs pre ethanol).
The real improvement that makes it worthwhile is the more flexible running at low revs, the absence of flat spots or pinking, not having to slip the clutch in traffic to avoid stalling. On the older cars this is also where the greatest economy gains are found. On the newer cars it is the top end performance that is better, less throttle needed on the motorway for a given speed on regular runs. Also the engine and exhaust run a lot cleaner, and the regular ‘Italian tune-ups’ of old are not required.
A few years ago I hired a car (Meriva) for about a thousand kilometres for a couple of weeks in France, and about halfway when I filled it up with V-Power the car was transformed, much more willing and not having to change down quite so often. However when I handed it back I’d refilled it with cheapest again.
Super unleaded makes no difference at all on my 2.0 Mk4.
Hi I posted this 7 months ago
Hi I’ve resently discovered sainsbury’s super unleaded fuel. I knew the mazda engine ran much smoother and was more fuel efficient on this stuff, but with the inflated price, was it worth it?
Whilst running the engine on premium unleaded I get a consistent 34 mpg. And running on super unleaded the engine returns 38 mpg.
From a touch of mathematics I’ve calculated that, if a litre of super unleaded was 12p more than premium unleaded, there is no mpg gain in monetary terms.
This where the Sainsburys comes into play because their high octane fuel is between 5 and 6p more than the premum stuff. So I’m getting 38 mpg 13.8 per mile plus the 2.0 engine is noticeably smother.
Its now winter, my car is a daily driver, and at present I constantly have the heater up high, heated seats on and the engine will run rich and take longer to warm up. Fuel economy is 35.8 mpg
Ive not put regular unleaded in the mx5’s fuel tank in all this time.
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Premium is 95 run of the mill, super is 97 to 100+
I was recommended to use v power by corten miller when i had their rotrex install. However i’ve had smoother results with tesco 99. I think some of it depends on the amount of super they are selling at that garage ie. How “fresh” the petrol is.
Most notable effect on mine is less discernible pinking if caught in a higher gear at low speed on super.
Mines supercharged and I once tried 95 RON on it and it ran like a pig in wellies.
I use Tesco Momentum in mine 99 RON.
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What a wonderful expression!
I thought exactly the same - make me chuckle!!!
Having tried super occasionally over the years in various hot hatches and high bhp /litre Caterhams my considered finding is I couldn’t tell any difference at all except once - with a MK 2 Golf GTi which gave about 3mpg more on super. I have consigned suoer to the snake oil category and I doubt if most people using it blind could tell any difference at all .
It’s certainly not “Snake oil”. Ask Rolls Royce, who carried out a huge amount of essential research into increasing the octane rating of their aero engine fuels during WW2, when the demand for more engine power meant everything.
Many modern cars run OK on 95 RON. But if your engine pinks (and some engines certainly do, depending on a number of factors, such as compression ratio, cylinder head design, amount of deposits therein, ignition settings (and boost if forced ignition), it would probably benefit from a higher octane rated fuel.
Modern ECUs have the facility to “knock back” (retard) the ignition advance if a knock sensor detects pinking, then the car will definitely lose some of its performance. Refilling with the correct grade should restore the lost performance. If in doubt stick to the minimum grade quoted by the manufacturer, however it won’t hurt the engine to try a higher grade of fuel. But some really don’t gain an advantage - normally those in a lower state of tune.
I learned to drive in the 1960s, on a grey Ferguson Tractor with a “TVO” engine - it had a dual fuel tank - start and warm it up on 2 star petrol then switch to TVO (about as close to paraffin as you could get - not even octane rated). The reason they could run on that stuff was that compression ratio of those engines was only about 4.5 to 1!
Wow - so what would mine need? It is a 2l mk4 sport nav.
It NEEDS minimum 95 Ron, beyond that is down to personal choice/finances etc., the only real way is to try different different ones and see which one suits you best. Good luck!
OK, some sad person needs to study both the NC and ND manuals. I’m sad enough, I’ve just done it. Here’s what they say. Capitalisation is mine.
NC Owner’s manual
Will run BEST on 96 RON or higher. Can use 91 - 95 RON but this WILL slightly reduce performance.
ND Owner’s manual
Will run BEST on 95 RON or higher. Fuel with a lower rating could cause engine damage.
So to sum that up according to Mazda if you have a Mk3 then you will get the best performance on the dear stuff but with a Mk4 you will get the best performance on the cheap stuff as well.
I’m pretty sure my Mk3 runs best on the Tesco 99 RON so I’ll believe that part.
I have no personal experience of whether the Mk4 will benefit similarly. I’m just pointing out that according to Mazda it won’t.
I’m not going to argue with anyone who says otherwise. You will be disagreeing with Mazda not me.
GeorgieMk4,
The best advice is that the car owner’s manual is always something worth taking notice of…
Until four years ago my competition car had an older design tuned engine (850 cc, pushrod valve gear) with a compression ratio of 13 to 1 (not my doing, the engine shop made a mistake and they skimmed the block as well as the head). It always needed super unleaded and I would use 4 star in the few places it was still available, but its best treat was a gallon of AVGAS mixed with five gallons of super unleaded. AVGAS still contains a fair amount of lead, even though it’s classified as 100LL (low lead) and doing this turned it into the equivalent of the old 4 or 5 Star leaded fuel. It really smoothed out the running and it went like the clappers on it. I couldn’t risk using any more than one gallon because the fuel system would possibly have been adversely affected by it - aircraft fuel systems are made from different material. Not to be done in an engine with a lambda sensor or a catalytic convertor - the exhaust gas deposits of lead salts would quickly ruin either, or both.