cr*p petrol
 

I've been using optimax since getting my MY99 UK TURBO nearly 2 years ago. I've had it remapped by BRD developements to use that fuel all the time.
So, when I nearly ran out yesterday/today, I had to fill-up at the local ESSO station with their superplus unleaded rated at 97 ron.
After having a knocklink fitted at the beginning of jan, and seeing nothing more than a bright first green on hard acceleration, in all gears, imagine my surprise when I saw the red light up when flooring it onto the motorway in stockport.
I was always a little sceptical about the benifits of using optimax, but this has shown that it is the safe option, and well worth the extra in the long run.
I'll just have to take it easy now until I need filling up again, and put the proper stuff in when it comes to fill up time :)

if you had been mapped the other way round then wouldnt the result have been the same.
ie, optimax/esso both good, just depends on what your mapped for.

I was kinda under the impression that only using a petrol with a lower Octane rating than that for which the car was mapped would cause Knock, so would be interested in hearing more about this. If my assumption is correct, I guess it would be best to have my car mapped for the 97RON -when the time comes-then if I can't get to a Shell Garage in time, no harm done!! :)

Regards.

the problem is that there is very little concrete evidence of the octane rating of optimax iirc.
BP super has a BS attached to it, which means it should acheive a minimum rating, optimax has no such BS, again, iirc.

mapping for 97 would be a good idea,broader choice, but you would possibly be losing out on everyday bog std. power.

Yeah, it's a worry- especially if we're to believe that even 1or 2RON out could make a big diff to knock activity. For the momnet I use Optimax and kep my fingers crossed...I'll be happier when I get that Knocklink!!

Regards.

Carry an emergency bottle of millers octane booster then if you get stuck & have to get BP or Esso then bung it in for that extra reassurance.

That sounds like a good idea.
Does anyone know if octane booster has a "best by" date if kept closed?

I've been caught out without Optimax a couple of times and will only put £5 or so of crap stuff in at a time and NEVER drive it other than sedately without optimax.

Alcazar

I live over 20 miles away from the nearest Optimax pump. Is it safe to use 95 ron with octane boost all the time?

If car still has its adaptive ignition timing enabled, it will react and retard the ignition to compensate for the drop in octane level. Presuming the knock sensor still works!

UK cars will run on 95 unless modified/ppp'd (to get past type approval) in which case SUL is minimum

Dropping the octane level without changing the ignition timing will cause it to pink. Simple fact.

Map it for 97 and be safe ;)...until you put in 95 by accident :D

thanks for the comments guys. Be careful out there with your modded motors :)

thats a cracking idea, think I'll be doing that in the future, cheers STEVECHAPS! :)

chris.

the esso stuff had probaly been there for a long time - dosent fuel degrade with time??

the shell garage on dowson road in hyde somtimes has bad batches (if they dont sell it it goes off)


mmmm dody

regards

Jud

CW42

Keep an emergency bottle of NF handy at work or at home :)

Unless it's a new bottle with the seal intact don't keep it in the car as the smell is quite distictive.......:)

Shaun

Just reading the bottle & no 'best before' dating at all on it.
Millers will treat 50 litres per 250ml bottle with a 2 octane rating increase IIRC NF is quite a bit stronger! (But costs a lot more).

Regarding crap fuel, I've had 1 occasion where a dodgy batch of Optimax from a single station franchise (dodgy!) lit up my knocklink like a crimbo tree (posted on here when it happened) so I stick to Co-op owned Shell stations or Service stations wherever possible.

yeah, I can testify that fuel degrades with time, my discertation is on it! In fact, we left a canister of research-grade 95 octane unleaded "slightly uncapped" in my garage over christmass and it was detonating all over the place when we put it in the research dyno. Must have dropped to 92 or maybe even less.

To risk sounding redundant: Use petrol stations that have loads of stock go through their pumps. The fresh stuff really is better.

I think the general concencus of opinion is that "fresh" fuel is best, optimax is better, and optimax with nf or some other booster is the best :)
Just goes to prove "you gets what you pays for" :)
Thanks guys.
chris.

Esso SUL (97 RON) is not crap fuel, I use it all the time on my JDM STI and its actually very consistent, it just doesn't have quite as higher octane rating as Optimax (98.5). Carrying a bottle of NF is not a bad idea if suffering from Det.

Do please keep us up to date on how you get on once you've refuelled. See these two threads of mine:

http://bbs.scoobynet.co.uk/showthread.php?t=391430
http://bbs.scoobynet.co.uk/showthread.php?t=399251

I'm having proper engine diagnostics done next week; I wouldn't have thought a bad batch of fuel would persist across several fill-ups, even if the tank wasn't completely empty each time. Or, is there some contaminant that can get into the system and drastically lower the octane rating of the fuel even in minute concentrations?

I've got to go to stoke this morning, so should use it all up by the time I get down there.
On reflection, it's been a false economy really, as now I just want to get the stuff out of my tank, and fill up with optimax!
chris.

My MY00 has been mapped with Optimax in the tank, and whenever I've had to put Esso SuperUnleaded in, I've never noticed anything other than increased 'sparkle' of the green LEDs on the Knocklink, under light throttle openings. At high RPM and load, the first amber has occasionaly shown - It certainly has never lit the red LED up!

I think that the next mapping session will be with SUL due to it being more readily available.

I'd be interested to see how much more ignition timing (at specific load sites) you could give a car using 98RON, as opposed to 97RON in the same car? - and the relative power/torque increase?

Richard