Shell Super unleaded

HillStreetBlues

born_again said:

But shell & BP round here are at least 10p ltr dearer than supermarkets...

My local supermarkets vary with their Super. Same price for normal unleaded, Tesco 7p dearer for Super at  Morrisons it's 18p

facade

pseudodox said:

The advice I received re E10 v E5 has nothing to do with the efficiency of the fuel.  Ethanol can corrode rubber, metal, and plastic parts in the fuel system, which can lead to increased maintenance costs.  I was advised that if I want to use E10 I should only put a limited quantity in the tank that I was likely to use quickly as if it sits there (as my car does often these days not go out much) the moisture absorption properties of E10 would be potentially detrimental.

I would never use e10 except in the direst emergency e.g. if a gallon of e10  just once was the difference between driving to a garage that sells e5 and walking 10 miles.

My 2019 car has just had a new fuelpump under recall because "The resin fuel pump impeller may become swollen and deformed when in fuel due to the insufficient material density caused by the improper injection moulding process
" (which really means they went and used JDM fuel pumps instead of export ones- Japanese fuel can be upto 3% ethanol max, most is ethanol free)

pseudodox said:

I would rather take advice from the professionals I consulted than random strangers on a website who don't drive old or classic cars.

After using E5 long enough for residue of previous fuel to have been cleared I also found my aged motor felt like it had a new lease of life as it seems to run smoother - like when I have taken a dose of cod liver oil.

I trust the photographic evidence that I have seen of the damage caused by ethanol fuel to the in tank fuel filters fitted to motorcycles. These have all been in the USA, and I suspect that it is caused by miss-fueling with one of the higher ethanol blends they get over there- upto e85 I believe)

At least my new supposedly ethanol rated fuel pump means I can risk Tesco's Momentum e5 instead of having to use Esso- that really was expensive  (but is supposed to be e0)

motorguy

Mildly_Miffed said:

motorguy said:

Car_54 said:

Some might say ... they probably think anyone buying "Super" petrol has more money than sense.

My car requires it to run optimally.

As do many cars.

Its sensible to use the fuel the manufacturer advises.

I very much doubt there's anything been sold on the UK market since the early 80s that REQUIRES the extra octane.

There have been cars sold that can make more power on it, especially turbocharged ones, but that's a different question. A base engine management map that sets boost and ignition for the higher octane, but will set them safely if knock/pinking/pre-ignition is detected. So the difference is only one of whether you need/use/will notice that extra power. If so, I suspect you are not driving in an appropriate manner for the road...
The manufacturer almost certainly gives a lowest-recommended octane value, quite likely 91RON, so everything above that is just fine.

Then there's the ethanol content.
Yes, there's a VERY slightly lower calorific value (energy content) for E10 than E5.
E100 has roughly 70% of the content of E0, so E5 (the standard since the launch of unleaded nearly 40 years ago) would be around 98.5% of E0 and E10 about 97%. Again, such a small difference as to be irrelevant to fuel consumption. Certainly nowhere near as big a difference (1.52%) as the difference in cost per litre (rarely under 10%, often nearer 15-20%) of premium and super.

The difference is a vanishingly small proportion of the overall efficiency of the average petrol car in turning the fuel's energy into motion - typically about 30% at absolute best.

The UK was really, really slow to E10 - most other European markets had it as the default a decade before us.
All cars sold in UNECE markets since 2009 must be compatible with E10, and quite a few older are, especially where they've also been sold in the US, since E10 has been the standard there since the 70s.

If i want it to perform as the manufacturer intended - which i do, yes it requires 98RON fuel.

And its not that "some cars make more power on it", its that some cars that require it will make less power if using 95RON.

My car - recommended 98RON, but it'll run on 95RON if needs be (with less power).

E10, not a problem, its the RON rating that means i use Super Unleaded.

motorguy

pseudodox said:

The advice I received re E10 v E5 has nothing to do with the efficiency of the fuel.  Ethanol can corrode rubber, metal, and plastic parts in the fuel system, which can lead to increased maintenance costs.  I was advised that if I want to use E10 I should only put a limited quantity in the tank that I was likely to use quickly as if it sits there (as my car does often these days not go out much) the moisture absorption properties of E10 would be potentially detrimental.

I would rather take advice from the professionals I consulted than random strangers on a website who don't drive old or classic cars.

After using E5 long enough for residue of previous fuel to have been cleared I also found my aged motor felt like it had a new lease of life as it seems to run smoother - like when I have taken a dose of cod liver oil.

Agreed.  Any classic car should be run on E5, because of the corrosive properties of ethanol.

pseudodox

I would only put E10 in if I was in danger of running dry & could not locate E5, but it would be a minimal amount to get me to an E5 supply when I would then fill the tank to "dilute" the E10.  None of the local supermarkets I use have E5, but a Morrisons near my cousins 20 miles away  usually has it at a good price so I run the tank low when planning a visit to said cousin & do a top up.

njkmr

motorguy said:

njkmr said:

I use Costco for fuel. 
Think it was £1:40 for the super unleaded equivalent.
They have two octane levels.
Used to be 90 or 97. Not sure if it dropped to 95 for the super unleaded stuff, but I put it in my cars and they run well.

Theres a difference between premium fuel and superunleaded fuel.

Super unleaded will always be 97 RON and E5.

Yes at Costco you have the choice of E5 or E10.
I use the E5.
the wife's newer car gets the cheaper E10 stuff.

Mildly_Miffed

motorguy said:

pseudodox said:

The advice I received re E10 v E5 has nothing to do with the efficiency of the fuel.  Ethanol can corrode rubber, metal, and plastic parts in the fuel system, which can lead to increased maintenance costs.  I was advised that if I want to use E10 I should only put a limited quantity in the tank that I was likely to use quickly as if it sits there (as my car does often these days not go out much) the moisture absorption properties of E10 would be potentially detrimental.

I would rather take advice from the professionals I consulted than random strangers on a website who don't drive old or classic cars.

After using E5 long enough for residue of previous fuel to have been cleared I also found my aged motor felt like it had a new lease of life as it seems to run smoother - like when I have taken a dose of cod liver oil.

Agreed.  Any classic car should be run on E5, because of the corrosive properties of ethanol.

Ethanol doesn't cause corrosion.

There MIGHT be a little more atmospheric moisture get suspended in the fuel if the vehicle's left over time - but, again, we've been just fine on E5 for a third of a century, so the change to E10 is unlikely to be dramatic.

It MIGHT be that some very old fuel hose can't cope - but it's probably well overdue for replacement through simply being old anyway.

As for "any classic car", remember that one of the best selling "performance" petrols from the 1930s to the 1960s was Cleveland Discol, which was E25.

WellKnownSid

My 80's Merc ran on E10 all the time before I imported it and still runs on E10 fine 15 years later - and that's the early K-Jetronic system.

I'm sure much older vehicles with carburettors and rotor arms may benefit from E5.

Goudy

Mildly_Miffed said:

motorguy said:

pseudodox said:

The advice I received re E10 v E5 has nothing to do with the efficiency of the fuel.  Ethanol can corrode rubber, metal, and plastic parts in the fuel system, which can lead to increased maintenance costs.  I was advised that if I want to use E10 I should only put a limited quantity in the tank that I was likely to use quickly as if it sits there (as my car does often these days not go out much) the moisture absorption properties of E10 would be potentially detrimental.

I would rather take advice from the professionals I consulted than random strangers on a website who don't drive old or classic cars.

After using E5 long enough for residue of previous fuel to have been cleared I also found my aged motor felt like it had a new lease of life as it seems to run smoother - like when I have taken a dose of cod liver oil.

Agreed.  Any classic car should be run on E5, because of the corrosive properties of ethanol.

Ethanol doesn't cause corrosion.

Ethanol is corrosive.

Adding ethanol brings oxygen to your fuel.
For some older cars it can cause corrosion within the fuel system, particularly to certain metals like cast zinc. (which old carbs were made out of).

It also causes problems for certain plastics, ABS, PVC and polyurethane.
Though these are not very common in fuel systems, older or modern.

Ethanol also absorbs water.
Your modern fuel system is pretty much sealed unless you open the fuel cap but older systems vent to atmosphere, which we know is full of water.

Your polish and show classic that sits without much use is more prone to higher ethanol fuels, but a classic that you use and regularly burn through tank after tank regularly, you shouldn't have a problem with the stuff.


As for octane, the higher the octane the more it resists pre detonation (combusting under pressure too early).
So a higher octane will allow for higher compression ratios and a more controlled spark timing, which tend to make more power.

Some cars, even today are designed/programmed to run on higher octane fuel.
That's not to say they can't run on the lower stuff.

Higher performance cars are mapped to make use of the resistance to pre detonation as standard.
And as already mentioned, knock sensors will start to detect pre ignition, then start to back things off at a cost to power when lower octane fuel is used and pre detonation is detected.

Your average car will be mapped to make use of whatever octane fuel is available in it's markets.
Some cars are worldwide models so will need to run on some iffy, limp wristed fuel available in a market, so will run on some pretty low octane fuel.

Some of these models might be able to make use of better octane ratings if used, but really the gains are small as it's original mapping restricts what the engine can do.

The losses for a performance engine designed to run on high octane fuel by running it on lower octane fuel can be quite pronounced.
It'll pull itself back quite hard to protect the engine from problems with pre detonation which can be quite damaging.

Albermarle

LightFlare said:

My previous car got ~10% extra mpg, was def more responsive and ran smoother with super

I used to fill up with it about 1 in 4 or prior to a long journey. The difference was noticeable (as was the cost)

(edit). Pretty sure there was a segment on 5th Gear (when it was good) about premium fuels and their benefit (or not) many years ago

I had a job with a lot of driving, so have had numerous cars over the last 35 years.
I had a Mercedes C class petrol around 20 years ago, and you could definitely feel it accelerate better with Super unleaded, and at the time the normal unleaded was E5, I guess.  They also claimed it was good for the engine, cleaned out the injectors I think.
However of all the other petrol and diesel cars I have had since, I could never tell any difference, not even when E10 became the standard.