I've been filling my car up with Tesco 95 octane for as long as I've had it and always been reasonably pleased with it. However, when the fuel contamination story hit I filled up at Esso using their 95 octane and found my car was sluggish and more unresponsive when I floored the throttle.

This month, I filled up with Tesco Super 99 octane. It cost the same as Esso's crap for a full tank and the difference seems quite significant. The throttle is more responsive, the car sounds less sluggish and just feels smoother.

According to a survey I read, Tesco Super 99 actually performs better than V-Power or BP Ultimate.

I drive a 1.25 16v Fiesta Mk5 Zetec (it's actually quite nippy) and I'm wondering if you LFS petrolheads fill up with regular unleaded or insist on high-octance super unleaded/Shell V-Power/BP Ultimate? And if you have changed fuel variety, what difference have you noticed/felt after switching?

We don't have Tesco here, but St1 which is perhaps similar cheap station. I always use 98 as there is no 99 or similar sold in other stations except Shell.

My engine won't run with 95, lot of detonation etc.

i use whatever grade is recommended for the car. going above the recommended grade doesn't get you any better performance, and more than likely gives worse fuel economy (in most situations).

now, if you've modified your car, you may have to go to a higher grade, depending on what you've done, or if you are getting detonation (ping/knock), then a higher octane might take care of that. if your car is pinging with the recommended fuel grade, then you should get the car looked at. could be a symptom of a larger problem forming. or it might just be in need of a tune up.

but, unless you're car specifically calls for a higher octane, stick with the lower octanes, except to stop pinging.

the higher the octane, the harder it is for the fuel to combust. which is why forced-induction cars and high compression cars call for it. in those cars, when using lower octane fuel, the air-fuel mixture is actually combusting on the compression stroke, before the sparkplug fires...and that's what knock/pinging is. so a higher octane is used. because it's harder to ignite, it can be compressed more and not combust before the spark.

when you use it in a car that doesn't need a higher octane, the fuel might not finish combusting before the exhaust stroke, and if that happens, you get worse fuel economy.

I use V-Power almost exclusively, and whilst I can't say I noticed a sudden improvement in power, response or smoothness, the range a tank of fuel gets has increased sufficiently over Tesco 'Normal' to make it more cost effective (more miles per £). If I can't get V-Power (Optimax was a much better name), then I use BP Ultimate or Tesco 99. Being a bit of a snob, I'm put off Tesco's product because of the word Tesco in the name.

Edit: 3 replies in the same minute - heh heh

Edit2: I adjusted the ignition advance from 10° at idle to 14° (as recommended by lots of MX-5 owners) to take advantage of the better fuel Europe has over Japan, and this in turn means I get more advantages from higher octane than a totally standard car. I also drive my car harder than the 'average' owner.

I read a test somewhere that those high performance fuels really don't have much effect on low powered cars (like yours). Only a high powered (sports cars and so on) have slight increase in power.

I myself don't really care where I get my fuel. I'll just look at the prices..

Vodka

Quote from geeman1 :

I read a test somewhere that those high performance fuels really don't have much effect on low powered cars (like yours). Only a high powered (sports cars and so on) have slight increase in power.

I myself don't really care where I get my fuel. I'll just look at the prices..

That is probably because of high powered cars have more advanced ecu that has less conservative timing and adjusts timing based to information from knock sensor etc.

I like high CR engines, I like more high CR engines with turbo

I've a Mk5 Fiesta Zetec-S, which I now run exclusively on V-Power due to increased range.

Regular gasoline here in the states is 87 octane. High octane gasoline ranges from 92 to 94 octane. The manual for my bike (250cc single-cylinder, DOHC, 9.3:1 compression, air-cooled) calls for 87 octane . However, I have always used V-Power (93 octane).

Must be nice to have such high octane gas in the UK. I have use 93 octane, and the highest I have seen is 94 octane at Road Rangers and Sunoco's.

Love to see what 104 octane would do for my WRX.

Quote from jayhawk :

Must be nice to have such high octane gas in the UK. I have use 93 octane, and the highest I have seen is 94 octane at Road Rangers and Sunoco's.

Love to see what 104 octane would do for my WRX.

You can't compare octanes from Europe directly, 93 should be quite close to our 98 if I remember right and 87 is somewhere between our 95 and 98, hmm or was it bit lower than 95, can't remember

yup. same grade of fuel. different rating number. its not like they are running racing gas over there

Quote from glyphon :

yup. same grade of fuel. different rating number. its not like they are running racing gas over there

Well, that is just silly. I would have thought that the octane rating would be standardized across the world.

Of course, if I were to visit to Europe, I could fool my friends back here in telling them that I was running some crap car like a Vectra with super high test 98 octane! "Dem europeeeans have some mighty strong fuel, ya hey!"

Diesel in the car, Petrol in the bike, any grade, they are all generally the same and with standard ignition/injection mapping higher octane fuel won't make any difference

The cheaper kind.

My fuel of choice would be water from the reservoir at the end of the lane. However, having tried it in a couple of cars I've found it entirely useless as a means of powering the vehicles. Despite it's attractive cost advantage against the more conventional diesel and petrol fuels, it seems to cause severe damage to the engines. The repair bills so far have offset any of the earlier cost-advantages foreseen so really it's not been much of a saving.
I cannot recommend it to you.

Quote from al heeley :

My fuel of choice would be water from the reservoir at the end of the lane. However, having tried it in a couple of cars I've found it entirely useless as a means of powering the vehicles. Despite it's attractive cost advantage against the more conventional diesel and petrol fuels, it seems to cause severe damage to the engines. The repair bills so far have offset any of the earlier cost-advantages foreseen so really it's not been much of a saving.
I cannot recommend it to you.

But it is still an option

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I usually refuel at Neste stations. The price is a bit higher (probably one of the highest) but I don't really drive that much that I would save a lot money. Also few years ago one finnish auto magazine compared the fuels from different stations and Neste was clearly the best one of those. Not sure of the test is applicable at all today though. Also you get teh Plussa from Neste

(it's the closest gas station)

Quote from Hyperactive :

I usually refuel at Neste stations.

Chocolate-powered cars FTW!

wow 99 octane! I wish I could get higher than 91 here.

Quote from LFSn00b :

I use 98 in my bike(Derbi Senda ftw ), i go usually to Neste or then ST1.

Is there any kind of vehicle you don't have?

I usually use BP Super Unleaded (98 octane?) in my kart but occasionally my dad decides to save money and buy standard Tescos stuff.

EDIT: My mum uses standard stuff from anywhere, usually Tescos or Asda. My dad uses standard diesel from Tescos usually.

Quote from thisnameistaken :

Chocolate-powered cars FTW!

Neste not Nestle

I only fuel up at Neste, using Neste's 98 petrol (we have statoil, lukoil and some other crap in Latvia though), It's a few eurocents more expensive, but who cares...

Quote from jayhawk :

Must be nice to have such high octane gas in the UK. I have use 93 octane, and the highest I have seen is 94 octane at Road Rangers and Sunoco's.

Love to see what 104 octane would do for my WRX.

Quote from JTbo :

You can't compare octanes from Europe directly, 93 should be quite close to our 98 if I remember right and 87 is somewhere between our 95 and 98, hmm or was it bit lower than 95, can't remember

Quote from glyphon :

yup. same grade of fuel. different rating number. its not like they are running racing gas over there

Quote from Roadie :

wow 99 octane! I wish I could get higher than 91 here.

From what I've read, the effect of high octane fuel depends on your car and opinion.

An modern-ish sports car with an ECU which can adapt will have better MPG and performance, an old car will see performance gains and a modern econobox will see MPG improvement and slight smoothness/performance gains as the ECU takes advantage of the new fuel. Or something.

After that trouble in south east england concerning fuel contaminated with silicon and "supermarket" filling stations i would advise people to get there fuel from company like BP or simular,

There were lots of oxygen sensors going wrong leading to hefty repair bills, Tesco being nice people said they would foot up the bill for repairs but its more of the inconvinience than anything else,