Fuel - Unleaded/ Super Ul

[Sol]

There is a thread on here about Optimax and BP ultiwhatever, but my question are more basic.

 

1) Does it really matter in an Elise whether you use normal unleaded/optimax or bp ultimate?

2) Can you mix 'normal' unleaded with Optimax/ BP Ultimate, or is it advisable to try and empty the tank as much as possible before using a different fuel?

3) What in hell is pinking?

4) Whats a knock sensor? What does it do?

[Scott_Mac]

1) No, it doesn't have a knock sensor so unless you have an aftermarket ECU reprogrammed to run on 98 Ron then it is fine on 95

 

2) Yes, makes no difference, ialways use optimax so thats never been an issue to me though.

 

3) Its "explosions" of fuel in the engine, caused by low octane ratings, higher octane rating obviously solves this

 

4) http://home.sprynet.com/~dale02/knock.htm

 

In short, I use Optimax, my car runs smoothly on it, does more MPG, feels more responsive and i've seen a report in Evo which showed how good it is at cleaning the engine... i also get double Plus Points from Shell

[Sol]

cheers Scott! Worth it just for the double plus points

 

Be interesting to know what others use and whether they think its worth the extra pennies..

[Scott_Mac]

I have nearly £200 worth of vouchers since i started collecting Plus Points - and that was approx 12 months back, so its deffo worth it!

 

Daves2111s became a convert after trying it... not sure about the other folks though...

 

The fact it is good for the engine and aids cleaning makes it worth the extra £1 per tank IMO.

[simon_prickett]

Slightly off topic - I'm currently doing 1500 mile experiments with Tesco Diesel, then BP Ultimate diesel in my Leon (daily driver). Will report back when done, but price difference is huge... Tesco = 78.9p, BP = 89.9p at my local (Donington Park Moto).

 

Got 53.98mpg on the Tesco stuff.

 

I use 95 RON in the Elise, and every 3-4 tankfulls use BP Ultimate to give it a flush through.

 

Simon.

[Kris H]

I don't use optimax or anything similar because of the knock sensor business - seems kind of like putting gold plated leads on a crap stereo to me - should help but the car doesn't actually know it's got better fuel and therefore what to do with it. All IMHO of course but mine runs fine on 95ron and I don't think it's worth the extra, although might try putting it in occasionally to see if there is a big difference.

 

Kristian

[GCCK]

The 95 v 98 RON issue is not the same as std 95 v Optimax/ Ultimate. As Scott says, with no knock sensor linked to advance & retard of ignition, the K series has no way of making use of the higher octane fuel.

 

However, the K series does seem to benefit from the claimed cleaner running. The fancy fuels have more/ different detergents to clean the injector nozzles, valves & ports so perhaps the K is more prone than other engines to gunging up?

 

I'm certain that mine runs a little more smoothly with better mid-range pull with the fancy stuff. Subjectively MPG a bit better too. It also seems to work as well alternating fills. My Dad's Rover 75 KV6 also likes the fancy stuff.

 

Conversely, in my other car (Mazda 2.0 engine) it makes absolutely no difference to perceived performance or MPG. It must be a case of try it and see.

 

Graeme

[Sol]

Kris, I know what you mean about gold leads on a crap stereo! Fair points really, I guess for a few extra pennies its worth using a fuel that has 'cleaning' properties every so often if not for any real performance reasons..

[Ruxpin]

I'm quite possibly wrong but i though standard unleaded is 95 RON and the super plus you can buy at most places is now only 97 RON. Its only Optimax and Possibly BP Ultimate thats 98 RON.

 

Can't say i've noticed much difference between 95 and 97 RON in the elise - to do with the car/ecu not being set up to benefit from the better fuel IMO. Doesn't stop me still putting it in though Makes me feel better, and maybe the car when it's being thrashed

 

My old man used to run a 2.8 quattro which was supposed to run on 98 RON - When you could still get hold of 98 RON fuel it made a big difference to mpg - easily paid for itself

[Scott_Mac]

<spanner into works>

 

According to various sources, Optimax is actually slightly better than Ultimate too as it has a higher MON rating...

 

</spanner>

[Simon G]

I didn't think Shell gave a RON rating for Optimax. They say it's higher than 97! It's cleaning properties are worth the investment alone.