Normal Unleaded vs Optimax

[D_T_W]

Just to help settle a discussion i was having with a mate of mine the other night.

He runs a 2003 STI Impreza and typically puts normal unleaded in it. Due to a bit of harassing by me, he switched from Tesco to Shell/BP normal unleaded. I mentioned he should start putting Optimax/Ultimate in it as it will run better. He said he'd tried it and hadn't noticed any difference. Despite me showing him numerous websites stating the STI should be run on at the minimum Super Unleaded, he still puts normal in it.

Now, i just need some sort of proof that the car should actually be run on Super unleaded, and that in putting normal fuel in it he risks damaging the engine. It does get driven fairly hard at times, though most is spent pottering round town or commuting to work. Only mods to it are cat back exhaust if that makes any difference. Please tell me i've not been talking shite!!

Ta muchly!

[Vixpy1]

It will be pulling serious amounts of timing on normal unleaded, especially with the raised boost the decat will bring. He needs to stick some v power in it for several tanks, and/or have the ecu reset so it can relearn.

Even with the ecu pulling timing to protect the engine, it might still be knocking. Tell him to use super or run the risk of blowing his engine up!

[Socr8s]

I believe there was an episode of fifth gear a couple of years ago when John Bentley actualy put an STI on a rolling road after filling it with Optimax and normal unleaded. There was a difference of about 15 BHP as I remember

[trickywoo]

He is clearly a fool.

For the sake of £3 or £4 extra a tank for super he is risking an engine failure and the car will feel nicer (smoother on the throttle) as well as make more power with super or the 99 tesco.

[stevieb]

trickywoo said:

He is clearly a fool.

For the sake of £3 or £4 extra a tank for super he is risking an engine failure and the car will feel nicer (smoother on the throttle) as well as make more power with super or the 99 tesco.

Yep even in my humble WRX i stick Super unleaded in as a minimum, and when out on a hoon i stick in a bottle of octane booster.

If stuck and cannot get any super, stick in my emergency supply of octane booster with normal unleaded.

It wven says inside the fuel filler cap a minimum of 97 octane fuel.

[D_T_W]

I'll point the daft pillock in the direction of this thread. He's not all that knowledgable about cars, he bought it because he read good reviews about it and he liked the look of the car

Cheers guys!!

[ScoobieWRX]

Failing all that, if he still won't listen, and when he destroys his P&J, make sure you don't forget to say..... 'I TOLD YOU SO!!!'

[MilnerR]

Always put V-power in mine. The owners manual says you should, the fuel filler cap says you should and every owner I've ever spoken to says you should. Why wouldn't you for an extra few quid a tank?

[Orangecurry]

MilnerR said:

Always put V-power in mine. The owners manual says you should, the fuel filler cap says you should and every owner I've ever spoken to says you should. Why wouldn't you for an extra few quid a tank?

Owners manual says V-power? Do you mean Super-unleaded?

My PPP classic runs better on Tesco99 over V-power.

[Lurker]

Socr8s said:

I believe there was an episode of fifth gear a couple of years ago when John Bentley actualy put an STI on a rolling road after filling it with Optimax and normal unleaded. There was a difference of about 15 BHP as I remember

http://fifthgear.five.tv/jsp/5gmain.jsp?lnk=601&featureid=143&pageid=-1

[Lurker]

Couple more links on performance, though not engine damage.

http://www.thorneymotorsport.co.uk/tuning/Fuel_Tes...

http://www.thorneymotorsport.co.uk/tuning/Fuel_Tes...

Quote (the webpage formatting is absurd):

thorneymotorsport said:

It is clear from the testing that whilst older engines show a clear benefit of running higher octane fuel, more modern, sophisticated engines have the ability to advance their fuel timing to take full advantage of this enhancement to a far greater degree. For the BMW M3 CSL the difference between running 95 octane fuel and Tesco 99 Octane fuel was over 40bhp, that's over 10%.

It is our fundamental belief and now our clear recommendation to our customers that if they want to maximize the power of their cars, before they even consider using our services to enhance the power of their car further, they should use the best fuel they can buy.

[ScoobieWRX]

TESCO 99RON Rules!!!

I went and bought some V-Power today for the fist time in bloody ages because i couldn't be bothered to go all the way to Tesco's, and i wish i hadn't now. It's running like a bag of shite and i guarantee if i go to Tesco's later this week for my shopping, i will get a 5ppl off voucher, fill my tank and it will be right as rain again.

So for the pleasure of having my car run rough it costs me 106.9ppl for V-Power....it's a bloody rip off when Tesco 99RON is 103.9 ppl + 5ppl off = 98.9ppl!!!

[RichyBoy]

I think it has more to do with how fresh the petrol is. I used a shell garage that I think hardly ever sells any v power and the car ran like a dog probably because the petrol was stale.

[MilnerR]

Orangecurry said:

MilnerR said:

Always put V-power in mine. The owners manual says you should, the fuel filler cap says you should and every owner I've ever spoken to says you should. Why wouldn't you for an extra few quid a tank?

Owners manual says V-power? Do you mean Super-unleaded?

My PPP classic runs better on Tesco99 over V-power.

You knew what I mean! Yes super-unleaded!


Try getting 99RON up in the cold hard wastes of the north! It's alright for you pampered southern nounces but us real men have to make do with V-power for our imprezas! Now, where did I put me whippet?

[ScoobieWRX]

Actually i think V-Power stands for Virtual-Power...it's just so unreal how crap it is

[Turbo T]

Funny, a very well known mapper I know says that V Power has a slightly high knock threshold to Tesco 99.

Optimax was notorious for going off quickly, maybe V Power suffers the same.

[Riknos]

Turbo T said:

Funny, a very well known mapper I know says that V Power has a slightly high knock threshold to Tesco 99.

Optimax was notorious for going off quickly, maybe V Power suffers the same.

I've seen tests, that were posted on PH in the GG a few months ago, showing the increased power from Tesco 99.
It being cheaper can also tip the balance.

RE: Original post. It tells you in the manual and the flap to put in 97RON, so listen to what it says!!!
Tell him to sell it and buy a saxo, he doesn't deserve a nice-ish car

[Vixpy1]

Turbo T said:

Funny, a very well known mapper I know says that V Power has a slightly high knock threshold to Tesco 99.

Optimax was notorious for going off quickly, maybe V Power suffers the same.

We find the knock theshhold higher in V power than 99.

[pbsaxman]

MilnerR said:

Orangecurry said:

MilnerR said:

Always put V-power in mine. The owners manual says you should, the fuel filler cap says you should and every owner I've ever spoken to says you should. Why wouldn't you for an extra few quid a tank?

Owners manual says V-power? Do you mean Super-unleaded?

My PPP classic runs better on Tesco99 over V-power.

You knew what I mean! Yes super-unleaded!


Try getting 99RON up in the cold hard wastes of the north! It's alright for you pampered southern nounces but us real men have to make do with V-power for our imprezas! Now, where did I put me whippet?

Eh Lad we 'ave it in Brid so yer must ave it in Sheffield!! Southern softie

[MilnerR]

pbsaxman said:

MilnerR said:

Orangecurry said:

MilnerR said:

Always put V-power in mine. The owners manual says you should, the fuel filler cap says you should and every owner I've ever spoken to says you should. Why wouldn't you for an extra few quid a tank?

Owners manual says V-power? Do you mean Super-unleaded?

My PPP classic runs better on Tesco99 over V-power.

You knew what I mean! Yes super-unleaded!


Try getting 99RON up in the cold hard wastes of the north! It's alright for you pampered southern nounces but us real men have to make do with V-power for our imprezas! Now, where did I put me whippet?

Eh Lad we 'ave it in Brid so yer must ave it in Sheffield!! Southern softie

Bloody hell, I'm trying to convince these southerners how grim it is up north and you go and ruin it by saying we have 99RON petrol, next you'll be telling them we shave with hot water!

There's a tesco in chesterfield that has 99RON but I'd rather sand-paper my own eyeballs than drive through chesterfield so I stick to V-power which is pretty good and very conveniently placed.