Why is it so important to use 98 ron petrol in my new WRX as stated on the Flap as I have just found out ?, the reason i ask is because the wife filled it up with normal shell unleaded i have filled my WRX 04 up twice once now with 95 ron will this affect my engine, and why does the engine need 98 ron ????

cheers.

 

Hello m8.... Not essential that you use 98RON but highly highly recomended... The higher the RON value the cleaner the fuel and the better the cars performance...

Its also most prob advised to use octance boost whenever you fill up on normal 95 RON fuel...

The car will go and go and go on 95RON but you will loose a bit of performance as a result...

Hope that helps

Gareth

 

Can you imagine being called ron and being 98, you would be reminded of it everytime you filled up


sorry

 

In short mate yes it will affect your engines performance, the 03/04 cars are mapped to 98ron, and as such continued use of 95 will cause the ECU to run concervatively (not damage it as such), so it will feel very very sluggish above 4k rpm....i found this after a month or so of having mine and i thought id broken it so took it back to the dealers.

Ive run it on nothing but optimax/Ultimate since and have had no repeat of the problem....

So my advice to you is to adhere to the fuel cap where its possible, otherwise when you put 95ron in it, dont drive it hard to long period cos it just wont feel right.

Neil.

P.S. Please dont get me wrong, it wont damage the car (to my knowledge) but you will feel that it stops pulling after 4000rpm when driving spiritedly.

 

Ok thats great help thx gareth and Neilo the one time won't hurt then


cheers for that..

 

Don't try going to fast with 95 RON in the tank. You'll probally blow the engine up

 

IIRC only the PPP maps are specific to 97\98 RON. The Subaru site states the WR1 needs 97 RON, and used to state 95 RON for WRX and STI. Since the website has been updated the fuel grade info has been removed.

 

My MY99 Wagon has super unleaded fuel on a sticker on the inside of the petrol flap (wasn't fitted with PPP when new)
Optimax only for me
Normal unleaded

 

yep same as scd Simon

 

The MY00 manual does stated use min 95 Ron fuel.
But I only run it on Optimax or SUL

Ray

 

Inside the fuel flap of my UK 2003 WRX it states 98 RON fuel only.

Brian.

 

It's a topic of some debate and I'm not sure anyone has a definitive answer.

AFAIK most UK Imprezas will run on 95 RON without actual engine damage. They will, however, only deliver optimum performance on SUL or, ideally, Optimax. The difference is especially pronounced with PPP or STI cars.

PPP on UK cars pre-'97(?) does require SUL and could be damaged by 95 RON.

The sticker in the fuel filler says 98 RON in almost all cases - even on cars which will run happily without damage on 95, so it's far from definitive.

Japanese imports are a different can of worms entirely - they all require the highest octane available (at least Optimax, ideally plus octane booster) to avoid damage, unless they've been remapped

 

Intresting info AndyC its also good to hear all the views.

 

Have had my MY98 UK Turbo with the FULL WR Sport Pack. ONLY EVER Run ON Optimax.

Its seems a general consensus....Higher the RON Rating the better the performance and long term engine maintenance...????

Dunno If that makes sense but Optimax ALL the way.....Even though It kills the pocket BUT the DRIVE more than makes up for it

 

The Pocket isn't the problem, I'm not that mechanicly minded on engines just thought i'd ask to see what the result was because of what it said on tha filler flap I used Opti first then the wife kindly filled her up after Only filled it up twice yet, but the last with standard only shell..

Thx for all ur views the wife has now been educated....

 

Optimax wasn't available in '98...

It's certainly true on all models that the higher the octane level, the better performance will be. There is, however, a big difference between reduced performance for the duration of that tank of fuel, and suffering engine damage!

 

well pointed out again AndyC...

 

Apologies if this sounds like a dumb question...

The WR1 is mapped for 97 RON fuel, so what effect would using 98 RON have, if any? I mean, would it be better (either in terms of performance, or engine longevity), would it be worse (eg. running too rich) or would there be no difference (so using 98 instead of 97 is nothing more than a waste of money)?

Cheers.

 

It would allow your timing to run slightly more advanced, ie more performance.

I don't think engine longevity would be affected, one way or the other.

It definitely wouldn't be worse, and it wouldn't cause it to run too rich.

Here's the daft thing. In the Midlands, Optimax is cheaper than BP Ultimate and Esso SUL... !

 

http://auto.howstuffworks.com/question90.htm

 

OK, I wasn't sure if this happened automatically or not, but I've read some technical specs now that says the ECU constantly varies ignition angle according to the quality of the fuel.

Heh, where I am it's more or less the same price, but I'd have to drive 5 miles to the nearest garage that sells 98 RON fuel, whereas there is a normal one just around the corner from me.

 

Good read.

 

what about if you put normal 95 ron in the tank but also use oxtane boost asweel, is that just the same as running say 98 or 99 ron fuel like optimax etc?

 

Same here in the North East.....Optimax 84.9p/l - Esso SUL 87.9p/l

 

It'll take the base fuel up a pount or two RON, getting towards optimax levels of 98.6 ish .. so unleaded with octane booster may be around 97?