Unleaded or super unleaded?
 

Just bought a uk spec 1999 subaru impreza turbo 2000 awd which i am absolutely loving. Am going to have to tank her up for the first time tommorow.

Wot petrol should i use? unleaded or super unleaded and wot make is best?

Thanks

Use Shell Optimax - you get get points too :D

Dave

Sod the points!!

Get Sainsburys SUL for 75p a litre!! luvverly stuff!! :D

Pete

not in my car I won't ;)

You continue getting ripped off then!! :D

Pete

Normal unleaded is fine. Car will make more power and feel better on super unleaded/Optimax.

I ran her on normal unleaded for the first month or so, then started putting Optimax in. Really can feel the difference. But iof the price difference is huge, I'd not bother with it.

--Rich

Whats it say on the label inside of the fuel filler flap?

For a '99 UK spec car, 95 RON unleaded is the minimum requirement for the car to run without damage. You will get better performance with 97 RON Super Unleaded, and should also get better economy which may cancel out the price difference. Most owners use Super.

Shell Optimax is, if I remember correctly, guaranteed to be at least 98 RON and is the fuel of choice for many scooby drivers. With an unmodified UK engine you may not tell any difference from SUL, though.

The label inside the flap contradicts the owner's manual. I believe it's aimed more at owners in other European countries where a cheaper, lower octane fuel is available, and 95 RON is referred to as 'super'.

Many owners choose to avoid supermarket fuels, as the quality and consistency of the additive packages they use (or don't use) is a topic of debate.

As a test I swapped from Shell Optimax to running Shell NUL for the past 2 months. I 'think' I notice a slight decrease in performance although that's very debateable since my car is standard engine wise.

I didn't notice any increased activity on my knocklink.

Agree with Andy. My fuel cap says 'Super Gasoline' BTW. No mention of RON or MON values. Owners manuals says at least 95 RON.

Stefan

Yep..NOT to be confused with Super unleaded. Fuels in different countries are given different names which do not relate to their RON values.

IIRC in some countries Regular Gasoline is 90RON, and Super Gasoline is 95 RON, then there's Premium Gasoline, which maybe 95Ron, oh, hang on. that's the same as super, erm, so super maybe 97 ;) - understand where I'm comming from? :D ;)

Bottom line is go by the minimum octane RON value printed on the back cover of your manual not by the filler cap. In your case...it will be 95 :)


The only exception is if the car is remapped or had a prodrive performance pack fitted (PPP), in which case you'll need at least 97.

I always thought that by using Optimax or SUL, it may prevent the odd blow up!!! So normal unleaded is fine for our UK cars?????

If the blow up on a completely standard engine was caused by detonation and lean fueling, then the curlprit is usually the MAF sensor, not the fuel. The car would run advanced ignition on higher octane fuel which maybe retarded by the knock sensor to a point, yet it will still run lean. So it could still melt pistons on 98RON.

Knocklink and a AFR meter is the best tool to prevent blowups :)

i put asda unleaded in mine.....no probs at all

Hit the nail on the head there. The reason supermarket fuels are cheaper is completely down to the choice and quality of additives. They all use the roughly same base however the quality of the detergents and other additives vary greatly.

So PSL et-al the mainstream fuel suppliers are not ripping you off, you are actually getting a better product for your money, long term it will produce less wear and tear on your engine and it will be kept cleaner.

I don't take much notice of what's written in the papers these days but the motoring agony uncle in the Telegraph (IIRC), Honest John, always advises against the use of supermarket fuel, especially for high performance cars and those used for short trips etc.

Not true. The '99 car with PPP will run without damage on 95 RON, it's earlier years that absolutely require 97. Performance is much better on 97 anyway, though.

If the car's been remapped, talk to whoever mapped it as the fuel used is one of the basic parameters used in defining the map.

NOT TRUE...Partially True :p

I can't keep up with all the model years :D

The sticker on the inside of my MY05 UK WRX says "use 98 RON Fuel Only"

So Optimax it is

Paul

Just checked the manual and it does say that if 98 RON is not available then fuel of 95 RON or higher should be used but will reduce performance...

So....

Optimax it is then!!!

Paul

When I was on holiday in Germany I noticed that the Shell garage offered 95 Ron, 98 and 100 Ron! I wish they would sell that over here. By the way even the 100 Ron was cheaper than our standard unleaded :(

So...........after reading this lot........I'll say it again

not in my car I won't :D:D:D:D:D:D:D (MY03 STI PPP with afew other bits!;))

It even looks like you can use 95 on a MY03 PPP STI (type uk of course), as the Prodrive blurb states....

Doesn't say you must use it only recommends, so I presume you could run 95 if you wished.

Regards,
Shaun.

Ive got an 03 wrx and on the fuel flap it says 98 super but in the owners manual it
says the wrx engine has been designed to run on 95 unleaded or higher.

Ive tried optimax and 95 unleaded and i find the performance difference minimal,so cos
of the big price difference i use 95 unleaded.

Carl

Should be fine - though you may get better economy out of SUL depending on how you drive. It'll take the ECU a tank or two to learn the difference, so you'd need to do a trial over several weeks to determine what works best for you.

Quickest and easiest way is to take the main fuse out or take the battery terminals off for about 20 mins (not sure if the later cars have the ECU reset connections under the dash).

Regards,
Shaun

You get out what you put in mate. Simple as that! :-)

If you wanted to save pennies, you purchased the wrong car! :-)

All the best.

Optimax only !!!!

The rest is junk

<flame suit on>

You pays your penny's!!, you gets what its is !!

:D:D:D:D

Well I have a Sti version 5 wagon with many handling and geometry mods which im sure wont make much difference to the fuel consumption etc but what may do is an ITG panel filter and a full TSL ss exhaust.

Now saying that I have many people tell me not to use optimax as the car would have been changed to uk fuel bla bla bla and some say that on normal unleaded it can mess up. Now what would be the best option for menormal Unleaded or Optimax

you get get points too :D

like I said......................

Stick in 95RON you will not notice any difference in RL on anything more expensive. If anyone is driving around in S181RJC it got caned for three years on supermarket UL without hic up and still showed 240bhp on the rolling road.

and if I wanted to pi$$ money down the drain for no good reason I'd have bought a Ferrari.

My car doesn't need super-duper Optimax to drive me to work every morning