The "Tesco 99 Ron" mini-review

really? i been tempted to whack it in the BMW as the manual says it'll run fine on 95 but you get best performance from 98 ron fuel and tesco is 99. i'll stick some in next fill up methinks

I have to use their 98 on the SD1 and have tried it on my 528 and to be perfectly honest can't tell any difference.

hmm tescos

My trials of UL, test car, 1043 E reg polo in blue :-)

95 ron, cof's and splutters and is bag of turd. 99ron, runs like it should do with 95.

Esso,

95ron, purrs like a kitten 98ron, as 95.

It'll only make a difference if your car has an ECU that's smart enough to take advantage of it by advancing the ignition timing automatically when the higher octane fuel allows it to do so - and most cars don't.

I.

As you see by Vamp's post at the top, BMW infer theirs do.

Like Dave, I've tried 99 in both my E34 525 and E39 528, with similar results. There was no noticeable difference, either in performance, or fuel consumption. OTOH in my import Celica GT4 turbo it did make quite a difference, but that car was setup for 100 RON which is available in Japan, so it was to be expected.

IMO there are few cars that can really use 98-99 RON fuel, and on those that can, any performance gain has to be offset by the increased cost. Mike.

I'm sure it would be very, very bad for mine.

What about cars that don't have an ECU?

As long as you reset the ECU and give it a good blast on the good stuff, even the UK cars can learn to love it. Mine did (optimax/super instead of boggo 95).

Same here, my car is mapped for jap fuel instead of the watered down piss we normally get over here, and it absolutely loves it compared to normal 97 ron (haven't tried Optimax as there isn't a Shell station for miles around here that I know of).

I should probably amend my original statement to "it's not half bad (if your car is able to take advantage of it)", heh.

Tried it lots of times in my 1.8T get an extra 70-100 miles per tank of fuel on long runs but thats it, doesnt really feel any faster :(

Shell Optimax feels nicer, don't know why

Even for those cars that can use it though, you have to ask yourself the question, is the better performance really worth paying up to a 10% increase in fuel costs. For most of those that do high mileages, I would suggest the answer would be no. Mike.

It depends. You may recoup some of the higher fuel costs in efficiency.

The Accord was smoother, especially during the warming up period. And she was less thirsty, but cash neutral..

I found it was more expensive to use Tesco99 or Shell Optimax in my Saab 900 T16 on a 500 mile round trip than it was to use boggo 95 unleaded. That's on the motorway with the cruise set at 75. Less efficient too- 31mpg on

99/Optimax and 34.2 on normal unleaded. Both identical trips done on quiet motorways at night.

Mike P

Aie!

On the other hand the previous shape BMW M5 feels noticeably quicker on super compared to ordinary unleaded _and_ is more economical too.

Shoot come to think of it on the above trip, four up and with the cruise control set a little bit higher, it was showing 32 mpg on super. The owner reported high 20s on ordinary unleaded...

It's 89.9ppl at the station I went to, which is only a few pence more than normal Super Unleaded.

According to the lady I spoke to last night it appears that at a lot of stations they are just using the 99 juice in the 97 Ron pumps. Makes sense as it would be pretty pointless having 95, 97 *and* 99...

There it is easy: you can advance the ignition manually (pe at the dizzy) and tune the car to take advantage of the better fuel. Just check the old manuals descibing the stting of the ignition with the stroboscopic lamp.

Quite useless for normal road cars actually, but it one wants to have a

100 HP 652cc 2cv-engine (up from 35 HP) revving 8200 RPM, then all bits and tricks must be exploited. Nope: it won't last long. 5000 km is a mayor succes, most end earlier with holed pistons.

Tom De Moor

One gets out ones trusty 13mm spanner and timing light and advances the timing manually.

My Capri is currently running very nicely on 16°BTDC.