Giving 97 Octane a try.

[Jocko]

Giving 97 Octane a try. My local Morrisons has a couple of pumps that supply 97 Octane petrol so I filled up with that today. It was 6p/ litre dearer than their standard 95 Octane, so nothing like as dear as the Shell V-Power.
My top up today was for 475 miles and the yellow light just on. I was delighted to get a calculated figure of 61.9 mpg.
I'll try 97 Octane for a few tank fulls and report back on the results.

[dave12335]

I’ve been using it since I didn’t realise my spark plugs were playing up. Seems a bit perkier with it although it is more expensive.

Is it environmentally better or worse, does anyone know ?

[Jocko]

Is it environmentally better or worse, does anyone know ?

As it releases the same amount of CO₂, it is no better.

In fact, the extra chemicals added may make it worse. Unless of course it returns better fuel economy. It is only the same petrol with additives!

[VicW]

Having used Tesco 99 Momentum exclusively for some time I am convinced that it doesn't do anything for the car's performance, additives or not, yet it gets good write-ups. My car runs and performs just as well on my most convenient alternative fuel which is BP 95.
I now alternate between Tesco 99 and BP 95 octane fuel so I am running more or less on 97 octane which is fine.

Vic.

[peteo48]

I keep coming back to this subject.

The supermarkets charge, typically, about 5 pence extra for their super fuels - ie above 95 RON. The majors - Shell, BP, etc - charge at least 10 pence extra.

Tesco claim to put extra additives in their 99 RON Momentum fuel. Sainsburys tell you absolutely nothing.

When you buy food, you usually get a list of ingredients including additives but, for some reason, fuel companies can just make generalised claims but you never get any detail.

So - is supermarket premium fuel just higher octane or does it have extra additives? What are the additives anyway? Is it just clever marketing?

[SuperCNJ]

It usually takes a little while for your ECU to adjust and adapt to the new fuel, it won't happen straightaway. I certainly noticed a difference in performance in my old Civic Type-R and 135i. It's not a huge difference but the car does seem to be a bit more eager. We've never tried it in the Jazz but will be filling up with v-power every few tanks in our new MK3 Sport to help keep the engine clean. There are a few youtube videos showing how the cleaning and lubrication additives in these more expensive fuels actually work compared to conventional fuel, so I'm fairly convinced they do work.  I doubt they would give any noticeable performance increase in a small engine like the Jazz though. I can't comment on fuel economy as I never really measured it nor can it ever be accurate enough (if I did) to be meaningful.

[peteo48]

Just done a back of the envelope calculation. I'm working on the basis that the supermarket high octane fuels have the same additives as their 95 RON stuff. Tesco apart, they don't claim otherwise and even in tests done on Tesco Momentum they found that deposits actually increased in one car they tested.

So I'd use Esso as I have several Esso stations near my home. Their fancy stuff will cost me £1.37 per litre so a 14 pence per litre hike on the 1.23 per litre I pay at Sainsburys for their cooking petrol. Given an annual mileage of 3,000 (give or take) and an mpg of 43.5 I'll be paying an extra £3.62 per month extra.

I can afford that and the other factor in my thinking is the type of driving I do - lots of short stuff where the engine rarely gets up to full operating temperature - I tend to think my engine is more likely to get bunged up than if I was doing a decent trip every day.

The rationale would change if I still at work and doing 35 miles per week day - a lot of it on the motorway. I was doing about 11,000 miles a year then so the fancy stuff would add around £15 per month to my bill.

Of course this might be b----cks but it's real b----cks!

[culzean]

I used to travel an 80 mile round trip commute in all weathers and found 97 octane would either give you a bit more pep, or more MPG.  Problem if you use the extra pep your MPG did not change much but if you drove normally I did notice about an extra 10% better MPG. Modern ECU and knock sensor combination means that the ignition timing gets retarded (spark is fired later in compression stroke) if knocking is detected - this reduces power output of engine, but protects it from knocking ( when the exploding mixture tries to send piston back down without passing through top dead centre ). Knocking is hugely destructive and will wreck the engine.  Pinking is a milder version of knocking and although not desirable will not destroy engine.  The ECU always tries to trim the ignition to its most advanced position for maximum power, with higher octane it can run more advanced because the explosion of the mixture is fully under control of the spark and is not being ignited by heat of compression ( as the mixture starts to burn it increases pressure in combustion chamber and lower octane fuel can ignite in an uncontrolled manner as it gets squeezed harder, if the ECU fires the spark later during compression the piston is already past TDC and on its way down before this uncontrolled explosion gets going) .   Direct injection petrol engines can run higher CR because at lower speeds fuel is not injected until nearly TDC on compression stroke, at higher engine speed the fuel is injected in the normal way into into intake stroke.

The ECU actually reacts quickly to any knocking detected, it needs to to prevent damage, the take away message seems to be that Knock detectors allow engines to use lower octane fuel without damaging the engine ( by retarding spark / reducing  power) - the other side of the coin is that if the knock sensors are not picking up any vibs the ECU will advance spark.  Car makers  maybe still do ship cars to certain parts of the world with engine set up for lower octane,  but I assume knock detectors mean it may not be so important ( and the 95 octane or higher fuels more widely available now).

[Jocko]

I bought an old Cavalier CDi with 90,000 miles on the clock and ran it for a further 92,000 miles before giving it to my nephew. God knows how many more miles he put on it in the two years before it finally went to the great scrapyard in the sky. It was run on supermarket fuel all the time I had it and never had any issues of getting "bunged up" or problems with emission testing. If it hadn't rusted away it would still be going now!

The last time I used 97 octane I found the car a little smoother pulling at low revs. MPG was marginally better, but easily lost in the "noise" of fill up figures. Mind you, as I said above I got 61.9 this tankful and 61.4 the tankful before, so I do get consistent figures if I do similar drives. However I will need to beat 64.5 next tankful to break even on price!

[Pine]

I have read that Costo and Sainsburys 97 Octane have exactly the same additivies as their 95 Octane fuels.  Tesco Momentum 99 did claim to have a better additive package than their standard unleaded. This was stated on the Tesco Fuels web page but the web site seems to have been taken down recently.  Greenergy, who supply Tesco petrol (and also have the contract to distribute Esso fuels) have the Quality and Technical Product information on their web site.  The Greenergy web site is worth a look at, they claim to be the biggest supplier of road fuel in the UK.

[peteo48]

I have read that Costo and Sainsburys 97 Octane have exactly the same additivies as their 95 Octane fuels.  Tesco Momentum 99 did claim to have a better additive package than their standard unleaded. This was stated on the Tesco Fuels web page, but this seems to have been taken down recently. 

Interesting and would explain why they are only 5 pence per litre more expensive than their 95 RON. I wonder if we can assume that the 10 to 12p premium charged by Shell, Esso and the rest is because they have additional additives. This means that the concept of running a tank full of the good stuff every now and then for cleaning purposes will only work if you used a branded product?

[John A]

I have read that Costo and Sainsburys 97 Octane have exactly the same additivies as their 95 Octane fuels.  Tesco Momentum 99 did claim to have a better additive package than their standard unleaded. This was stated on the Tesco Fuels web page, but this seems to have been taken down recently. 

. I wonder if we can assume that the 10 to 12p premium charged by Shell, Esso and the rest is because they have additional additives.

My guess is that the only safe assumption is that they think they can charge a premium for what might be considered a premium product. Or am I being overly cynical?

[trebor1652]

I remember trying Tesco momentum when I had my 1.4 mk1 and the mpg fell through the floor.

Sent from my moto g(6) using Tapatalk

[Jocko]

Only done a few miles since filling up, but I genuinely do think that low speed pulling is even smoother than with 95 octane.

[bus_ter]

The last time I used 97 octane I found the car a little smoother pulling at low revs. MPG was marginally better, but easily lost in the "noise" of fill up figures. Mind you, as I said above I got 61.9 this tankful and 61.4 the tankful before, so I do get consistent figures if I do similar drives. However I will need to beat 64.5 next tankful to break even on price!

How do you get these figures? Very impressive from an older petrol car. Is it the slightly smaller 1.2 engine that's making the difference?

When driving intentionally economically I can see 55MPG on the car (about 52MPG when I do the calculations). So you're getting 10MPG more!