Optimax

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Discussion

CRAPLOGINNAME

Original Poster:

362 posts

190 months

Tuesday 8th April 2003
quotequote all
Is there a boffin out there who can explain why I'm getting more mpg out of optimax then normal unleaded?

I'm mystified!!

Thanks in advance

deltaf

6,806 posts

189 months

Tuesday 8th April 2003
quotequote all
Yes. Optimax like superplus has more calorific energy per gallon than plain old unleaded.
I found years ago that my old audi would go approximately 4 miles further for the same fuel quantity of super as opposed to ordinary unleaded.
Presumably, the fuel burns more efficiently/ hotter maybe, so giving that extra mileage and power they always promise us.
But i could be wrong!


>> Edited by deltaf on Tuesday 8th April 14:38

>> Edited by deltaf on Tuesday 8th April 14:38

Podie

45,178 posts

211 months

Tuesday 8th April 2003
quotequote all
I've also found that BP super unleaded gives as good MPG as OptiMax... dunno what BP put in it, but it's rocket fuel!

CRAPLOGINNAME

Original Poster:

362 posts

190 months

Tuesday 8th April 2003
quotequote all
I've also done a little anorak type calculation - based on 78p per litre vs 83p per litre (normal v optimax) I get 11.6p per mile Optimax v 11.8p per mile normal....just needed the figures to justify to 'er indoors why I'm buying expensive juice...'look luv, it's cheaper in the long run'

Alan420

5,316 posts

194 months

Wednesday 9th April 2003
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Fantastic, a real excuse to go fill my motor with top grade motion-lotion.

P.s. Can anyone explain why Optimax slowed my cavalier down by 1/2 a second to 60 and returned APPALING mpg (1/4 tank in 50 miles!)
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neilr

1,076 posts

199 months

Wednesday 9th April 2003
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Evo did a test with optimax a while back, ran a variety of cars on normal unleaded (either super or not depending on manufacturer recc.) for 1500 miles then on optimax for 1500 miles, they tested MPG, acceleration thru gears etc, and used some kind of endoscipic camera to test the claims that it cleaned valves etc. It was a very positive report, concluding that it did what it said on the tin. frim memory I thnk they used a Civic Tyoe R, M Coupe, I think there was a Jag in there of some descrption too...

MEMSDesign

1,100 posts

206 months

Wednesday 9th April 2003
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deltaf said:approximately 4 miles
What, not a whole 4 miles.

Seriously though, 4 miles difference for what quantity of fuel?

Mr2Mike

20,050 posts

191 months

Wednesday 9th April 2003
quotequote all
I'm, not convinced that Optimax has a higher calorific value, does it say this anywhere on the Shell web site?

Having a higher ocatne rating than any other readily available pump petrol will give a small power/mileage gain to those engines that can use it (mainly turbo's and Jap imports that are designed to run on 100RON anyway).

However, higher octane petrols generaly burn more slowly, so if an engine is specificaly design to use a low octane fuel, then it may well see a slight power loss without ignition adjustment.

M@H

11,217 posts

208 months

Wednesday 9th April 2003
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My 4.0 definitely seems to give a better MPG on Optimax.. and no risk of pinking..

Matt.

mikes

96 posts

192 months

Thursday 10th April 2003
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The original Shell marketing info implied that Optimax had a higher calorific value and a minimum octane rating of 98RON.

I have tried it in various cars - good in Accord Type R, Primera GT andPug 309GTi. Makes no discernable difference to 3 litre (210bhp) 406.

charisma

93 posts

194 months

Thursday 10th April 2003
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I did notice that Optimax gave slightly better fuel consumption in my Elise, however my nearest Shell garage is 5 miles out of my way...

zefarelly

229 posts

193 months

Friday 11th April 2003
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my vixen runs better on it, as does my 1700 xflow MK1 cortina . . .the v6 mondeo doesnt run any different, but I think its a bit more economical, whether theres a financial benefit Im not sure

Alan420

5,316 posts

194 months

Friday 11th April 2003
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Been running the Escort on it for a few days now.

It definately has more torque, there's a steep hill near me that I can now climb in 3rd wheras 2nd was the limit on normal petrol. The car is MUCH smoother at low revs in any gear, has stronger engine breaking, better low end pull and sounds nicer to boot.

Needless to say I'm impressed. It's also on target to match unleaded fuel consumption, possibly even beat it. I'll keep you posted.

Mr2Mike

20,050 posts

191 months

Friday 11th April 2003
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Alan420 said:
has stronger engine breaking


I'd love to know how this is when the engine is using virtualy no fuel on the overrun (in fact no fuel on modern injection engines that cut fuel to reduce emmsions).

[Edit] Perhaps it's gumming your engine up and making it more difficult to turn



>> Edited by Mr2Mike on Friday 11th April 13:03

zefarelly

229 posts

193 months

Friday 11th April 2003
quotequote all
I get more pisht on optimax, although @ 47.14 pPP its a little more expensive than regular unleaded, it digests well, and doesnt sting when you go to the loo

I gave up on diesel, gives me terrible wind

tedebear

177 posts

191 months

Friday 11th April 2003
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zefarelly said:
I gave up on diesel, gives me terrible wind


Thank heavens for that

Alan420

5,316 posts

194 months

Friday 11th April 2003
quotequote all

Mr2Mike said:

Alan420 said:
has stronger engine breaking


I'd love to know how this is when the engine is using virtualy no fuel on the overrun (in fact no fuel on modern injection engines that cut fuel to reduce emmsions).

[Edit] Perhaps it's gumming your engine up and making it more difficult to turn



>> Edited by Mr2Mike on Friday 11th April 13:03


Don't ask me, I'm only an engineer...

Seriously, it may be my imagination, but it certainly seems to keep to a certain speed better down hills.

Is that how overrun works then? I never knew... Could it be cleaning the insides of the engine so it seals better or something? It is a bit knackered...

bogbeast

907 posts

199 months

Friday 18th April 2003
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I log the fuel consumption on my cars pretty accurately.

My average MPG went from 21.1 (common & garden Super unleaded) to 23.6 (Optimax). Measured over 15 tank fulls

I was gobsmacked .

Toffer

1,520 posts

197 months

Saturday 19th April 2003
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TVR suggets that the Griff 500 is run on 98RON unleaded petrol. The super-unleaded fuels are marked as 97RON. On teh SHELL website they say OPTIMAX is 98RON and is "octane boosted". The fuel is supposed to give better engine response and performance when under high load conditions. OTIMAX is also supposed to "clean" the engine (probably not a good thing on an old engine!).

In conclusion, I have tried a number of different brands of super unleaded and found that OPTIMAX provides the best performance (no pinking, smooth running and stable idle) and does marginally improve fuel consumption. I am in absolute no doubt about the benefits of using OPTIMAX in the Griff 500.