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MG ZT-T 190
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Optimax was discussed at length on the MG BBS...
I have used it a few times, both in my 620ti and in the MGZS 180.
Improvements I found difficut to detect in short term.
Both the Rover and MG are not short on power anyway.
I keep saying I will a longer term test... maybe soon!
 

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the voice of reason!!!
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I tried askingon another board, didn't really get a general concensous of opinion. The question is being asked again elsewhere.

Is Optimax petrol worth the extra for modern MGs ?

Owners of older cars seem to think that it gives them an extra bit of performance, but no-one seems to have tried it in a Zed.

:confused:
 
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I use 97 RON SUL in the EVO & thus buy Optimax if I can't gel SUL.

The car is designed to run on 98+ RON.

It should make a difference, as any higher octane means energy; thus power.

However, for our normal daily our driving techniques I doubt you would feel those extra horses.

If your car is designed for 95 ron I would use only only and save some "hard earned". Unless you are doing a track day or other event that requires more power.

The www.lancerregister.com has also talked about this at length!
 

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Richard (Bitten Hero) uses Optimax religously in his Scoob. I think he reckons to gain mpg as well as being able to hold higher boost due to the higher octane. Another friend with a Leon 20VT also uses SUL/Optimax and reckons the mpg increase pays for the extra cost.

On the other hand a friend with a Primera GT tried it and found no difference. I have also just started trialing it. If there is more power, it is not perceptable. I'm not able to comment on the fuel consumption, though first impressions suggest little difference.

My gut feeling is that turbo'd motors, with ECUs that can exploit the octance, will benefit from optimax - and will produce enough extra power from the fuel that there will be mpg increases which compensates for the extra cost. Naturally aspirated engines, however, even if they can advance the timing due to the higher octane, will not produce signifcantly extra power or better mpg.

Once I've run a few tank-fulls through the car, I will post my findings on the forum - but my guess is that I will be going back to regular UL.

S.
 

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Yep, definite difference on my car. Smoother pickup at lower revs, and the anti-det characteristics of the fuel mean that rather than the power tailing off above around 6200rpm, it now holds 255bhp from 5500-6800rpm. The Scooby is well-known for having quite an aggressive ignition timing advance/retard mechanism, and re-learns new fuel fairly quickly.

I changed back to NUL for half a tankfull (not by choice - got caught out in Wales) and peak boost dropped back within a few miles from around 17.5psi to 15.5psi. Once I put Optimax back in it and did an ECU reset (to make it re-learn immediately) then the boost went back up to 17.5psi.

The general consensus on the Scooby board is that it does make a difference, particularly on the newer cars, but some people with 94/95 cars have reported worse running due to the different characteristics of the fuel.

At the end of the day, I guess it depends on how much your ECU can capitalise on running richer fuel (Optimax is 98.6RON), and as the effect is a percentage increase, it will be more noticeable on high-power and turbo cars.

Hope that helps! :)

Richard
 
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Mentioned elsewhere today about SUL and Optimax. Not readily available in some parts of the country. You would think that Shell would sell it - especially after their televison campaign advertising the stuff.

You know that ESSO - don't sell SUL. But in the Oxford area TOTAL - SHELL & BP sell the stuff.

Elsewhere in the country this is not the case - seems to be very area dependant. looks like people in Lincolnshire don't want performance or don't drive performance cars. :(
 

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the voice of reason!!!
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No problems getting Optimax ans SUL around here, also know of a few garages in Lincoln that sell it.
 
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JLD said:
No problems getting Optimax ans SUL around here, also know of a few garages in Lincoln that sell it.
John - I'm sure there must be some - the Shell station south of Lincoln did not even stock the stuff. I must have been unlucky - but I tried 5 stations on my route without luck :D Fifth - had to put £5 UL in! :(
 

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the voice of reason!!!
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Seem to remember Optimax being available at tyhe shell station at the end of Burton Road (?). No problems at all in Scu*thorpe.
 
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I'm sure you are right - but it was one of the roads (Burton) I never went on! Miss the R75 SATNAV! :D

Oh! will pop into setup and change the rules so you can write S****horpe. :)
 

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My experiment with Optimax has now been concluded and I can comfirm that there was no difference in fuel comsumption or any perceptable difference in power compared to a good quality unleaded. I have previously found that supermarket U/L, for instance, gives fewer mpg than a decent branded fuel.

As I said before, this is what I would expect for a naturally aspirated engine, as it does not have the mechanism to increase the effective compression ratio that a forced induction motor does, so is not able to make use of the higher octane rating. The only thing that the ECU could do is to advance the timing but this is very definitely a second order effect so, even if the Siemens ECU will do it, I'm not convinced that the improvement could be reliably measured without an RR.

HTH,

S.
 

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the voice of reason!!!
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Article and test results in latest Evo magazine about the benefits of Optimax. Worth a read.
 

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It might be all in my head, but I'm sure I get better MPG out of Optimax, cant say I feel more power though, some days are better than others:confused:, might be down to air flow through the turbo???

I only put Optimax in, unless Im caught short, then normal unleaded goes in.
 

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I've replied to this else were on the forum.. I changed to 98 ron with my last car (ZS120+) and on a 300 mile trip used a quater of a tank less fuel.. I got a ZS180 now and always use 98ron so I havnt got anything to compare it to,, By the way.. 17p a liter for my 98ron/optimax....:D
 

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Must admit that I am canning through tanks of petrol now. The average MPG for my last tank was 24.4 !:) However, do find that Optimax doesn't really give a power increase, but does give extra MPG. Tight decision as to whether it is worth the extra cost.
 

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As we know the ZS does run 95 - 98 and the ECU will adapt, but as Steve says its negligable if you notice any difference on the Zeds.

I'd say after running Optimax a few times, if you run a couple of tanks to let the system settle down it does "seem" better low down with smoother pickup. As for MPG well can't see any difference its still around 22-23 regardless of fuel type.

Does it warrant the cost? for performance gains no not really on our cars, but longer term it should keep the engine cleaner and therefore deliver the performance more consistantly over the long term.

There again I could be talking out of my :moon: :D
 

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Certainly going to be treating the ZT...

Being as I have to get rid of my Smart for more seats, when I get the ZT then I'll be trying Optislurp in that too... certainly in the Smart, running on Optislurp is like driving a different car... the engine is so much smoother, pickup better, and slight improvement in mpg... could all be down to the fact it's turbo'd and works better as per earlier comments in the thread, but I will certainly be treating the ZT to some...

Andy
 

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Chinese Crackers
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Andy
I certainly notice a slight improvement on the 160KV6 ZT, and I have run mine regularly on this since day 1, with the odd departure when caught short. I even run the Mini and GT and on the GT, after 1000 miles, the carbs looked very good for a car with 120k miles on it. On older cars, the timing can be advanced with Optimax (love the optislurp!) unlike the timing settings for cars running normal unleaded which have to be retarded. The ZT (or rather the KV6) can make adjustments to the fuel type unlike the other Zeds. However, the ZR/ZS could probably be set up on a rolling road with Optimax (preferably after a couple of tankfulls) to get optimum performance.

HTH
 

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sul

as i am a forcourt engineer we have been doing a few grade changers on bp and esso sites where they have changed the lrp to sul due to the sucess of optimax
 

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Chinese Crackers
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Thanks for the info, at least a bit of competition might bring the price of Optimax down a fraction. Wonder what the RON is on these? Most super unleaded is 97 in the UK with Optimax at 98, but in Europe most super is seemingly all 98, and cheaper!
 
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