View Full Version : Optimax Test
Been having a trial with Optimax v Std UL.
Luckily I have a Shell garage round the corner from both home and work. I have been running the V5 purely on Optimax but noticed that the car felt 'ratty' when in slow moving traffic (jumpy / lurches).
So I tried this over 10 tank fulls of fuel (I use 2 a week). One full of Optimax then one full of Std UL, Optimax, std etc. etc.
I have noticed that whilst the pick up and responsiveness is better with Optimax, along with an average of 2mpg more, the car is consistantly much smoother to drive in slow traffic with Std UL.
Now me thinks the ECU is detecting a higher octane and adjusts the timing (advances slightly I guess), thus causing the jumpy behavior on and off the go pedal in a queue. Not a problem just an observation.
Anyone else tried / noticed this ??
Next plan is to start annoying the forecourt cashiers and use half a tank of Optimax and half a tank of Std. I will see what happens :)
Jimmyboy
17-01-2003, 09:40
Originally posted by Stubill
Next plan is to start annoying the forecourt cashiers and use half a tank of Optimax and half a tank of Std. I will see what happens :)
I've done this before during the petrol crisis a couple of years ago. One pump ran out of fuel so I moved onto the next one. When I went to pay I hoped the cashier would have forgotton that I'd been to 2 pumps.....but she hadnt!
My ibiza 20vt runs loads better on std 95 over optimax and super UL. Ive heard this optimax stuff can go off/stale very quickly too so you may be using a bad batch, or its sat at the forecourt for quite some time.
Glad to hear it's not just me then Mike.
Sad but true, I have also done the maths :
Optimax = 2.7% better fuel economy than UL (for my car)
Optimax = 7.7% more expensive than UL
Seems like a bad investment to me.
As I seem to spend a lot of time in slow moving traffic then 95RON UL seems to be the way I am swinging ! Maybe the odd tankful now and then for cleaning purposes.
my leon cupra runs best on standard 95 UL. I do put the odd tank of optimax in to clean the engine, but i can't say it goes any better...
i used optimax from day 1 and it sometimes felt good, other times sluggish. so i slapped in a few tanks of 95 in and from then on it flies. so from now on im gonna stick with 95, cheaper too!
mark sheerin
17-01-2003, 13:07
My car runs better on SUL..but not from a supermarket..from a proper supplier...
As for problems with Optimax...
I'm of the opinion that Turbo engines only suit Optimax when they are spinning above 3500 rpm..
Here you get the benifit of the extra power.
If you read the Optimax litrature it says it 'burns faster' than std petrol..
This could be why optimax isn't suited to Turbo's like ours because at low revs the full burn is taking place before TDC and having the effect as mentioned as if your ignition was too far advanced.
At higher revs the burn wouldn't be able to peak ahead of tdc as the time for the combustion to take place is more limited..then it will give you the power benefit required.
I use optimax in my wifes normally aspirated Ibiza 8v Cupra and SUL in my Leon Cupra
Jimmyboy
17-01-2003, 13:09
I thought Optimax was specifically designed for turbo cars?
From the horses mouth :
Quote :
Shell Optimax is a completely new, highly refined unleaded petrol which burns more cleanly to give you smooth power delivery and increased engine protection.
We went back to the drawing board to build the ultimate performance petrol and started by selecting the individual molecules which should go into the fuel. Using this approach and the same technology we use to develop petrol for the Ferrari F1 cars, we produced a unique formula: Shell Optimax - the best performance unleaded petrol in the UK. Shell Optimax is designed to enable fuel and air to flow smoothly and quickly to your engine. This means that Optimax burns more cleanly and efficiently than regular petrols to give you increased performance and a quicker response. It also protects your engine better than any other unleaded petrol.
You can use Optimax in any engine which runs on super unleaded or unleaded. It is an ultra low sulphur petrol.
End Quote.
If this speil is true and they developed it in the same way as F1 fuel then me thinks it's not designed specifically for turbo charged engines ;)