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MG ZR ZS ZT Technical - Shell Optimax

Hi

Is it ok to use Shell Optimax (98 RON) in the ZS180 KV6. I've been filling up with std unleaded up until now but would like to see whether this fuel will give any noticeable performance benefit.

I'd be curious to know what others are using?

Mike
Mike

We put optimax in the ZS180 whenever we get the chance, it certainly doesn't harm the performance and it definately improves the fuel consumption.
Nik & Anita

Have to disagree on the fuel consumption. We have a 75 with the 2.5 and the full electronic gizmos of cruise control, sat nav and on board computer. Filled up with Optimax for a trip from London to Edinburgh with nearly all the journey on motorway with cruise control set to just under 85. Drove back the following day, same route same cruise control using standard esso "cooking" unleaded. MPG on Optimax just over 30 and on Esso 32.

Now you could argue that the journeys could not be identical and I would agree. However I did not expect the Esso cooking to return 7% better consumption! The car only had 2k on the clock so you could also argue that it was more "run-in" on the way back. But you cold also argue that it was downhill!

Cheers

Patrick
Patrick

I'm with Patrick on this one. I ran a few tanks of Optimax in my 180 and found there to be no significant difference over a good quality standard unleaded. (Coincidentally the NUL run before and after the Optimax also showed slightly BETTER efficiency!) I have found in previous cars that Shell, Esso, etc. unleaded gives consistently better fuel efficiency than supermarket unleaded. With Optimax, I've found that friends with turbocharged cars swear by it, while those with naturally aspirated cars found no difference when they tried it. This makes sense as, to benefit from the higher octane, you need to increase the compression ratio. Turbo'd cars can do this by increasing the boost, whereas NA cars have no way of doing it. All they can do is advance the timing a few degrees, which is a second order effect that is not likely to produce a significant improvement, IMO.

_
Steve H

Read the Optimax blurb, fill up the tank, and for a while you actually believe your going further and faster.
But do your sums like Steve H and indeed there is no benefit! The extra U pay is not worth it! For the last 4 years or so I have been pretty much loyal to Esso fuel, Shell seems often to be 1 or 2p more expensive!

Kelvin
Kelvin

Been through this a few times on the F board, as many of you will know. The general consensus is that although Optimax may deliver slightly improved smoothness and fuel consumption, they do not justify the added cost. The MEMS is not designed to take advantage of the better fuel, and I'd imagine the ZS120 would be the same as the 1.8 F. The ZS180 I have no idea.
David Bainbridge

I've had my ZS 180 for three weeks now and I'm very pleased so far, with the exception of fuel consumption. Now its run in I've filled up with Esso Super and I think the only real difference is the cost and perhaps a little more pickup, or there again it maybe I'm getting more enthusiastic with the throttle .

Just out of interest what sort of fuel consumption are you guys getting, I am averaging about 25 to 26 MPG ! also having had a few good blasts on various roads I find that the 139 stated top speed is a bit optimistic although 0 - 60 seems to be 7 secs dead. Has anyone had chance to check out top end performance without being caught ?
mike hammond

I've never used Optimax as it seems to be very expensive. I have occasionally put BP 98 RON in and haven't noticed any difference and accidenatlly put 20 litres of BP 91 RON in in Germany.

As for top speeds. I originally did 130 up the M1 at 6am one Sunday morning when there were absolutely no other vehicles about and my ZS180 seemed to have a fair bit left in it.

So, a few months later whilst driving to Germany I gave it a blast a few km short of the German border in the Netherlands (the roads are much smoother) and took it up to exacly 140mph on the speedo (before I bottled out), and there still seemed a little bit of power left, and it's pretty flat around that area. Only managed 120mph in Germany, as there was too much traffic. I'm not partularly fond of running the car flat out for too long.
Alex Rogers

Hi all

fuel con. seems to vary a lot I have been a little un happy with mine at aprox 30-32 mpg its now done 15000 so at 7100 i converted to LPG and save aprox 23 quid on each like for like fill up. by the way mine has just visited rover for a check up and it seems to have lost its edge, its is smoother and makes much less noise, but it seems to have lost somthing!!! any one else had the same thing?
David

Dave,

if your getting 30 to 32 MPG you've had your engine knicked and a 120 unit put in its place, perhaps thats why the performance has dropped off ??

Joking apart though isn't not the case that LPG is the culprit for your performance drop off, my old man used to have a Jag XK8 with LPG and he reckoned he saw a noticable tail off in performance when pushed hard, but the cost saving at 16 MPG were worth it.

Also how does it effect your warranty ?


Regards

Mike
mike hammond

This thread was discussed between 15/04/2002 and 21/04/2002

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