Esso have also gone the way of 'ultimate' 'supreme' 'optimaxy' type marketting on their Superunleaded - the thing is, it used to be rated 98 but is now only 97 ...

I was chatting to my old man yesterday - he was telling me that before the days of unleaded, you could get a couple of high octance fuel at the pumps, and when I say 'high' octane we're talking 100-102! ('Golden' any of you guys old enough to remember?) 'Course it was all leaded, but jeez 100+? that's almost Avgas territory!

 

dude, you have to take into account something that seems to escape most people: Octane rating doesnt actualley relate to the calorific output of the fuel (hence it's 'power') but to the sensitivity the fuel exhibits to 'knock' (commonly refered to as Detonation or 'det'). Hence, higher octane fuel doesn't necesarily mean you'll get more power out of it. It does mean that your car can dial in more ignition advance and injection pulse with less fear of detonation, and as far as i know, subarus have a detonation-detection mechanism that will lessen ignition advance if it detects your cylinders getting close to the crucial points. Overall, higher octane fuel is safer, but not necessarily faster.
-Antonis

 

/\ What he says /\

Esso SU was rated 97 before anyway & not 98

 

ah Ok; the finery of knock resistance vs energy capacity has indeed escaped me ... but all else being equal, an engine that can modify it's advance curve electronically to take advantage of the shift in the knocking point will no doubt make more power the more advance? to a point no doubt ...

@daz34 - the pumps actuially stated 98 on them ...

 

SUL used to be 98RON in the UK, it was dropped to 97RON about 3 years ago.

 

So we are all right then

 

I remember the good old days (early seventies!!)of five star fuel mate which was 100 octane rated!!
I used to run a 1600 gt cortina with the head skimmed right down and it would pink like a pig on anything except five star.
dave

 

lol - the thing is, my nearest garage only apparently swapped over in the last week or so - hence the basis and point for the thread ...

I wonder if the measurement basis has changed - eg the US 'RON' system differs from the UK.

 

it was full of lead, nice

 

The USA dont use RON, they use PON (pump octane number)

PON=RON+MON/2

 

AVGAS is 100LL - low lead so the stuff you're talking about would exceed this.

 

Ok this my not be a scientific appriasal but my car goes like stink on sainsburys SUL
It runs like a pig and BP Ultimate... probably becouse its so f$%£$ expensive its crap! and it between the two on Optimax ...

The reason i'm so happy is that one the car really feel great on S-SUL and the stuff cost the least at 84.9 ppl I can't believe it...

The difference is amazing id stuck £15 of BP in and it just ran crap... very uneaven through the revs.. you could feel it backing on and off as it pulled... got down to very empty.. maybe just a couple of litres left put in £15 wot of the Sainsbury stuff and it clear as night and day... very srong! I've now done this about 6 times becouse it thought i was going mad, and for defo the Sainsburys stuff is the best, better even than the optimax...

It would be interesting to see what others think...!

dazza

 

Sainsbury's SUL used to be my close second choice in my 172 (after optimax), and to be honest the car performed equally well on it!

Haven't tried it in scoob yet though, although I'd agree with BP Ultimate being crappy!

Dazza's STI- what year is your STI?

 

just put the new esso sul in last week after optimax and it does seem to be running much better especially low down.

 

Speaking of BP Ultimate, jasonius, 9 months before it was launched in the UK it was tested in Greece, and over there you can still get it at a breath-taking 100 octane... It's honestly not bad, I came over to the UK and smilingly pumped my car full of Ultimate at the first BP I found and was left with my mouth gapping wide. The Ultimate you get over here is not only 97 octane, its also hopelessly underpowered. I'm pretty happy with both Esso 97 and Optimax nowadays though. But I'm still looking forward to going back to Greece for some of that good BP stuff...

 

They do PON RON MON

They do John, mon.

 

lmao

 

 

03 m8

 

yes coundnt agree more , car goes like stink (04 sti ppp ) have you noticed the stronger smell as well ? , its 83.9 at Colton Leeds store which is cheaper than normal unleaded at most other garages

 

PMSL Top class

 

"noticed the smell"

apparently (and no doubt been covered a thousand times on here already?) - the current crop of SUL have a very short shelf life - examples quote anything between 3days and two weeks ... ever had 'difficulty' starting when not used your motor for a couple of weeks? The fuel's lost its edge - characterised by the distinct lack of the usual petrol type arooooma

Other forums I've been on cite Optimax as particularly prone to this and I've even seen copy documents showing that Optimax is actually deliverd at something like 100RON and due to the old **** it gets mixed with ends up being 97 through the pumps and after a few days is no better than regular ... I've noticed this myself as a performance drop off when stretching a single full tank of the stuff to over a week.

 

Mine is definately smoother lower down on Esso SUL as opposed to Optimax which I used solidly for a year.

 

Unless Sainsburys have changed their supplier in the last few months, Sainsburys fuel is supplied by BP. The same stuff just with a JS label on it.

AFAIK anyway

 

Ahh the sixties, I remember it well. I had a couple of Rover 2000 TC's back then and HAD to use 100 octane - and it still pinked! Shell was the best at 101
Why do other European countries get higher octane fuel?
I remember de-coking one of the Rovers at 20k - the valves were laden with crud! More recently a Mondeo with 35k had no build-up on the inlet valves at all. It shows how petrol and oil have improved over the years.
I reckon there could be a lot of "placebo" effect between brands?
JohnD

 

In the north (Yorkshire , Lancashire ) Sainsbury load there petrol at Linsey oil refinery at Immingham which is owned by TOTAL , might be different in other parts of the country , All supermarkets buy there petrol of the major oil companies as they dont have refinerys

 

Optimax seems to drop power on my TEK'd MY00 too.....
If I put £40 in it will last me about 2 weeks. In this time the last 1/3 or so of a tank it starts to feel a little flat.
I couldn't really put it down to the fuel until I started using ESSO SUL on a regular bassis.

With the ESSO the car seems to perform well and consistant irrespective of what level or how long it's been in the tank (within reason).

The Knock sensor activity is pretty much the same too...

I also found with Optimax that my old MY94 would hesitate when first driven in the morning slowing down for speed bumps in my street. I tried all sorts of things to fix it, but after using different fuel whilst away on holiday the hesitance stopped. Optimax in the tank the week we got back and it came back within a couple of days.

thinking about it the MY00 also is more surgey when cold too, when using Optimax.

I also think my local Optimax forcourt doesn't get through much, so it probably sits in the tanks a bit longer then those in more afluant area's of the country.

I might try Sainsbury's SUL next week, cause their right next door to the ESSO. Which is nice cause it helps keep the ESSO a little cheaper due to the competition, about 86.6p I think (Only 3p more the UL).

P.S The BP Ultimate about 1/4 from there it a rip off at 90.6p

 

My Dad's old Norton 750 commandos both ran on 5 -star, every once in a while he manages to get hold of some AVgas just to turn the engines over for a few minutes

 

Ah!! The good old days. Can't remember the last time I de-coked an engine. We tend to foget how much maintenance we had to do in them past times.
I just love modern cars. Lots of power smoothly and reliably, most handle well and with a bit of care and attention go on for years.

 

Just to add,

Had Esso SUL tested about a year ago when we suspected an engine problem had been caused by bad fuel. Rang Esso up, they tested the batch and it came back as 98.4ron.

Swear by the stuff, car feels more 'alive' on Esso SUL than 'Opti/mate'.