Omega Owners Forum
Chat Area => General Discussion Area => Topic started by: Squatch on 29 February 2008, 11:38:13
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I am sure that this has been asked before (possibly on numerous occasions) so apologies in advance. Is there any benefit to be gained from using Shell optimax/BP ultimate? Does the engine (2.5 V6) have a knock sensor that can sense such fuel and advance the timing accordingly? Do the additives in this fuel clean out muck and improve performance? Or is it a complete waste of money marketed at eejits like me?
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The V6 does have a knock sensor. Opinions vary as to how much performance difference there is between regular and super.
My view is that unless the engine has very high compression or forced induction good quality 95 octane will probably allow enough ignition advance for best power on an efficient 4 valve combustion chamber. So, theoretically, there shouldn't be much if any difference.
As to the cleaning properties - It's marketing speak so who knows how it relates to the real world? I haven't experienced my engines getting particularly "dirty" on bog standard fuel.
I guess trying a tank or two is the best bet. If there is any ignition adjustment due to the (lack of) knock it could take a while before you notice a difference. Once you're tried it you can make your own mind up whether it's worth the extra cash.
I try to use Super in my kit car, but it has a shade over 11:1 compression on standard cast pistons and no knock control. It makes a noticeable difference on that engine but not on my 3.2 MV6.
Kevin
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On my MV6 3.0l, I don't notice any difference of Optimax over standard Shell (though do between Asda/Tescos and 'branded' fuel). I do not a slight improvement to performance and mpg on BP Ultimate petrol though, though not sure whether worth the extra...
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Supermarket fuel is definately worse.
A straight Tesco Shell comparison on 95 found that ont the Somerset levels I could gain 2 or 3 mpg and maintain top gear easier on a 2.0 towing a caravan.
I have not done the same test with the 2.6 as Propane is too cheap!
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Hi
Have tried it in my V6 and it did not seam to make any difference. We allways use it in wife's Volvo S40 T4 (200bhp) and it seems to increase average mpg from 20.7 to 21.6.
HTH
Mike
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Here in Finland we have 95, 98 and Shell´s V-Power 99 octane.
I think there is a noticable difference between 95 and 98 octane in the X30XE.
Car feels quicker and more economical on 98 octane, even though the 98 is more expensive.
I havent noticed a big difference between 98 and V-Power yet...
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As I have seen, "High Octane" petrol in UK is 97 usually with some cleaning addatives. In my opinion this it the reason why there isnt a big difference. I tried 100 octane ARAL petrol in Germaty once.There was no cleaning addatives and the car did more MPG and was accelerating better.
You can buy 91 oct petrol in Germany as well, and it's called "benzin"!! 95 is "Super Benzin"....
It's proven that any cleaning/boosting addative reduces power of ca 2%.
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I lived in Iowa and then California for many-years and both states have 87 RON and 91 RON std. at the pumps.....in Iowa they also have 10% Ethanol-enriched 95 RON.
I used all the major-brands of 95/91 & 87 RON fuels in my trucks and cars then (big and little engines) and did not ever notice much 'real-world' difference in performance/economy....or perhaps electronic fuel management is very good at disguising any shortcomings?
Would U.K branded-fuels be formulated very differently from the US types?
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I am sure that this has been asked before (possibly on numerous occasions) so apologies in advance. Is there any benefit to be gained from using Shell optimax/BP ultimate? Does the engine (2.5 V6) have a knock sensor that can sense such fuel and advance the timing accordingly? Do the additives in this fuel clean out muck and improve performance? Or is it a complete waste of money marketed at eejits like me?
There a petrol station close to me in Maidstone that sells 102 octane fuel, I wonder how well that will go, would be tempted but it £2.64 (last time I looked) per litre
http://www.bp.com/faq.do?categoryId=9009089&contentId=7016946#1
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i tried it in my 2.5 recently,didnt notice any difference in performance.i do have possible access to aviation fuel,i think i might try that the week before the car takes its last journey to mr scrappy. :)
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i tried it in my 2.5 recently,didnt notice any difference in performance.i do have possible access to aviation fuel,i think i might try that the week before the car takes its last journey to mr scrappy. :)
I assume you mean AVGAS and not the kerosene based AVTUR.
Be aware that you will be taking it to the scrappy, or replacing
both Cats. The high octane rating achieved by AVGAS is due
to the tetra ethyl lead additives. :)
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If you want high octane convert to autogas
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i tried it in my 2.5 recently,didnt notice any difference in performance.i do have possible access to aviation fuel,i think i might try that the week before the car takes its last journey to mr scrappy. :)
I assume you mean AVGAS and not the kerosene based AVTUR.
Be aware that you will be taking it to the scrappy, or replacing
both Cats. The high octane rating achieved by AVGAS is due
to the tetra ethyl lead additives. :)
yes it is avgas i was offered some to try in my bike to see if it gives it any more grunt :y
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On my MV6 3.0l, I don't notice any difference of Optimax over standard Shell (though do between Asda/Tescos and 'branded' fuel). I do not a slight improvement to performance and mpg on BP Ultimate petrol though, though not sure whether worth the extra...
the only difference is the pennies not in your pocket ;D ;D ;D
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I tried to do a small comparison with the old beast (the 2.5) and these were my results :
On Optimax the car felt a little more responsive, slightly more "grunt" but that is highly subjective and may be wishful thinking :)
On long CONSTANT SPEED runs, especially with the 'van on the back, I got around 6%-10% BETTER fuel consumption, and as the price at the time was only 4% higher this seemed a good idea, better fuel consumption + more grunt = a happy towcar... :) ; however, this all changed with a compulsory off motorway detour after Mr Plod closed the M6, non-constant driving the consumption was identical to normal fuel, so was effectively more expensive. I did try using cheap Sainsbury's stuff but the car just didn't seem to like it, so never finished the comparison.
HTH
:)
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I tried BP ultimate in my Scorpio several times, it certainly gave the impression of more urgency, I never actually checked the mpg but I seemed to be the pumps much as before.
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"cheap Sainsbury's stuff"
.....should actually be BP sourced fuel :-?
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I lived in Iowa and then California for many-years and both states have 87 RON and 91 RON std. at the pumps.....in Iowa they also have 10% Ethanol-enriched 95 RON.
I used all the major-brands of 95/91 & 87 RON fuels in my trucks and cars then (big and little engines) and did not ever notice much 'real-world' difference in performance/economy....or perhaps electronic fuel management is very good at disguising any shortcomings?
Would U.K branded-fuels be formulated very differently from the US types?
Actually there is very little differance, as US fuels octane ratings are PON not RON, and 87 PON is about 95 RON
Stewart
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just had my mig powerchipped and on super unleaded (OPTIMAX) the mig runs alot better
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Theres a Airfield near me sells Avgas, my Cossie loves the stuff (no Cats to worry about) not cheap though.
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If you use avgas, be aware that it contains quite a lot of tetra ethyl lead, it's generally labeled 100LL, low lead, low is relative. It probably will destroy the cats very quickly.
An interesting article in Flyer by Miles Mcallum describes the aviation petrols available. 100LL is 100/130 octane, weak/ rich mixture, but octane measurement is done differently for aviation fuels. The motor equivalent is around 105.
There is 80/87 sometimes available, perhaps 95 motor octane, probably contains enough lead to turn politicians into idiots ands cats to junk.
Although the excise duty appears to be lower, avgas is significantly more expensive than motor fuel per litre. It also has a fairly distinctive smell.
Be interesting to see how it performs.
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I`d be very cautious about using AVGAS in any engine/fuel system not designed for that specific fuel....it`s not just about having a higher octane level than road fuel.
I have an aircraft with a Lycoming engine designed to run on AVGAS 100LL which has seals/diaphragms etc. formulated for use with only that one fuel; aircraft-engines with approvals for use on MOGAS have to have their fuel system`s seals/diaphragms/plastic-components etc. changed completely for use with that fuel.....and of course vice-versa.
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I`ve seen hoses and seals perish within a very short time when exposed to the wrong fuels. :o
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I hear all the arguments regarding running the car on Shell V- Power, on a personal note I filled up 9 times in February, 6 times with V-Power, the engine sounds just a little quieter and is a more responsive, the breathers are also kept clean. Current price is £107. 9 a litre against £101.9 for 95 octane so cheaper than a additive.
Please give it a go, fill the tank a couple of times see what you think.
regards
richard
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Hi,
When I had the Prelude ,which was a Jap Import I certainly noticed a difference in using Optimax (as it was then)as the car was designed for use with a higher octane fuel. I was once forced to use a supermarket fuel on a long journey and experienced what felt like "pinking " in the drive. When I first got the car I don't think the previous owner had bothered with a higher octane fuel and consequently ,on initiallly using Optimax it seemed like it cleaned it up a bit . I,m not at all mechanically minded really but I've also got a turbo diesel Emina and in order to get it through the m.o.t. emissions test I had to add a cleaner to the fuel and thrash it up and down the dual carriageway for a bit for it to de-coke as , at the time, it was only being used for short journey's. I can only liken the initial use of Optimax in the Lude to this. As for whether it's all hype, I do remember a test in Jap performance or Banzai mag where they compared high octane fuels from places like Tesco to Optimax and BP Ultimate and there WAS a marked difference in performance with Optimax being out in front then Ultimate and with the others lagging a way behind. In respect of these Jap cars and my experience with the Prelude , Optimax did make a difference. Like anything else you gets what you pays for,- just don't swallow all of the hype!I still use V-Power in the Omega(V6 2.5) but I certainly don't notice such a marked improvement over ,say, standard Shell-and there can be quite marked differences between the quality of some supermarket unleaded and brand unleaded-maybe I'll do what a lot of others do which is to alternate between the two, in the meantime I'll have to stick to the V-Power as my little lad's still got a few more toy Ferraris to collect!!
jerry :)
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I've used optimax in a variety of vehicles and have always noticed some difference. It varies on the complexity of the engine management and or state of tune. My Cavalier 2lt ecotec, Senator 24v and a tuned Carb'ed motorbike were all faster, more urgent rev response, and returned better MPG. In the Senny it actualy cost me 4% more and returned 7% better economy (there abouts) so overall saved me money to use a more fun fuel.
It does take a full 2 tanks to see all the difference, give the ECU chance to adjust, dilute down the old fuel and a few miles to clean out the system.
So its hard to feel an 'instant' difference, as it happens gradually. What i do say to nay sayers, is put it in for two full tanks, then as you about to run out, take her out for a propper taz around, then refill with supermarket fuel and try again straight away.