Super Unleaded - i cant see the point - who runs it?

Malt_Vinegar · 9 Jul 2009 at 12:27

ringo747 said:
How does one know if you should be using it or not? My mate runs it in a VXR Astra and says he has to and its better for it but i'd have thought it was for a lot higher spec machines. He also has some funny notion about sitting in the car for 5 minutes at a standstill before he switches it off and turns off the key. Some 'essential cooldown period' apparently.

Turbo car then, standard procedure on most hot turbo cars. Some users just back it off for the last few miles to avoid boost to allow it to cool.

When you turn the engine off, the turbo loses its coolant supply, and can damage the thing if it gets too hot.

You can get "turbo timers" that allow the engine to run on for a few minutes, after getting out and locking the car. Saves you sitting about waiting

Sin_Chase · 9 Jul 2009 at 12:27

ringo747 said:
How does one know if you should be using it or not? My mate runs it in a VXR Astra and says he has to and its better for it but i'd have thought it was for a lot higher spec machines. He also has some funny notion about sitting in the car for 5 minutes at a standstill before he switches it off and turns off the key. Some 'essential cooldown period' apparently.

Cooldown is important... if you have things you need to properly cooldown

Easier to just drive the last mile or 2 easily and let everything cool down then instead of sitting like a plonker in an Astra like its got a turbo from a Articulated lorry in it

stoofa · 9 Jul 2009 at 12:27

Diesel said:
I use Shell V-Power in my Octy vRS, runs better on it and like a bag of crap on normal unleaded.

Cost isn't a problem because I don't do many miles.

If your Octy is running like a "bag of crap" on normal unleaded I'd get it taken in and looked at.
It's got maps for 95 & 98 RON fuels.
If it's having problems with the lower octane fuel I'd say you've got some problems with the vehicle.

ringo747 · 9 Jul 2009 at 12:29

Is the cooling in modern turbos not done by synthetic oil or something which still 'moves' within the unit even after the ignition has been cut?

Jez · 9 Jul 2009 at 12:30

merlin said:
I'd be surprised if there was no accomodation in the Porsche's ECU map to advance ignition on 97/98 ron fuel.

Ive tried playing with it extensively. Its identical on both as far as i can tell.

Seems that a lot of people agree in general that its all nonsense on most cars, i still believe that its in people's heads most of the time

So, V-Power Diesel, LOL. Anyone use that?

BigT · 9 Jul 2009 at 12:31

When I had the Boxster I was advised not to bother with SUL. The Z4M states that the car should be run on higher Octane fuel so I do. I have no idea if there is extra power or better fuel consumption, but I like the idea of the cleaning properties of V-Power. Could all be hype, but I don't put enough in to make a huge difference to my wallet so my default behaviour is to put the best into it I can. I use something like 2,000 litres a year so I guess it works out at £100 extra or so. If I add in other running costs (tax, insurance, servicing etc.), then the differential must account for less than 3% of my annual running costs which is acceptable to me.

PMKeates · 9 Jul 2009 at 12:34

Jez said:
Weird given that i have owned three cars with the same engine as yours, and have never seen any difference between any of them

You're probably just less perceptive than I am

I don't have a standard map on my car. Maybe that causes it... though I think your first 330 (Merlin's) didn't, either?

I doubt it's possible for there not to be a difference, tbh. The engine has a knock sensor for a reason. It wouldn't exist if it didn't need one, although they do serve other purposes.

Skiddley · 9 Jul 2009 at 12:36

I've had an LCR in the past too, and it made no noticable difference. Same on the current Pork.

antijoke · 9 Jul 2009 at 12:39

Never used anything but unleaded in any car I have owned, the one exception being when I had an Impreza, and then I only put super d00per fuel in when I Was feeling thrifty, and that did run better on the good stuff.

Dogbreath · 9 Jul 2009 at 12:40

ringo747 said:
Is the cooling in modern turbos not done by synthetic oil or something which still 'moves' within the unit even after the ignition has been cut?

No, the oil is moved by an engine driven pump in the majority of road cars, so as soon as you stop the engine you stop the oil flow. Synthetic oils can withstand higher temperatures so tend to form less deposits but it doesn't mean you can just turn the engine off with a red hot turbo and think it's going to be fine.

FWIW I use SUL all the time in the Coupe because I don't want a repeat of what happened to the previous owner (broken/melted ring lands). Very few normally aspirated production cars require 97/98 RON.

Jez · 9 Jul 2009 at 12:40

PMKeates said:
I doubt it's possible for there not to be a difference, tbh. The engine has a knock sensor for a reason. It wouldn't exist if it didn't need one, although they do serve other purposes.

I imagine the knock sensor is there for the prevention of issues with very low grade fuel, not our comparatively resistant (by world standards) 95.

Funny how a lot of people are posting that they have the same cars and it makes no odds, reinforces it to me that it in people's heads.

Oh well, can only be a good thing for me financially if people keep driving the super unleaded market

PMKeates · 9 Jul 2009 at 12:43

Jez said:
Funny how a lot of people are posting that they have the same cars and it makes no odds, reinforces it to me that it in people's heads.

The fact that it doesn't make a difference could just as much be in your head, as that the fact that it does make a difference is in ours. It works both ways

I never noticed much of a difference in any of my earlier cars.

Hxc · 9 Jul 2009 at 12:43

I think I got better economy when I put super in by accident once.... although that's probably my driving style.

What octane was old style 4 star out of interest?

bledd · 9 Jul 2009 at 12:44

Malt_Vinegar said:
My prleude states in the fuel door thingy that I must use 95 ron, or higher.

So, I use standard unleaded. I have used a few odd tanks of special stuff, when i have a voucher or something, just to try it. No difference felt by Butt Dyno, or fuel economy

I am sticking to 95ron

yeah, my ITR fuel flap says to use 98ron or higher, but also says it will run on 95, but the ECU will adjust the performance accordingly..

Dogbreath · 9 Jul 2009 at 12:45

Jez said:
I imagine the knock sensor is there for the prevention of issues with very low grade fuel, not our comparatively resistant (by world standards) 95.

If you had a turbocharged car whose manufacturer recommended a minimum of e.g. 98RON, would you still experiment to see if 95 made any difference?

Duke · 9 Jul 2009 at 12:46

I don't do many miles, only one tank a month, so always put in V-Power/BP Ultimate/Tesco 97 (can't get 99 locally). I have no idea if it improves MPG/Power or not, that doesn't matter anyway, I only get it as they are meant to have better cleaning stuff in them, which I think is quite handy for a 10 year old engine

Malt_Vinegar · 9 Jul 2009 at 12:46

Hxc said:
What octane was old style 4 star out of interest?

98 ron

PMKeates · 9 Jul 2009 at 12:47

Hxc said:
What octane was old style 4 star out of interest?

A minimum of 97 RON and 86 MON to BS4040, so typically what a good super unleaded is.

Wicksta · 9 Jul 2009 at 12:48

My old E36 M3 used to pink using normal unleaded, this was in 1998 when it was a fairly new car so maybe petrol has changed a bit now.

jaybee · 9 Jul 2009 at 12:52

Always used unleaded. Always will do even if I buy a turbo'd car, I'd have it mapped for 95ron. Petrol prices are high enough as they are thanks. I've never felt a difference in performance or seen better mpg when I have tried it in the past.