Unleaded Or Super Unleaded?

Goggy · December 23, 2015

I've seen various mentions on this subject, so thought it may be worth its own thread. So far I have only used 'Normal Unleaded' in my NX, is it worth using 'Super Unleaded'? I have heard various things, some say it makes no difference unless it is a high performance car, some say it will help keep the engine clean and will give extra MPG and some say just use it once every 4-5 fill ups to help the engine. I have no idea which is right. Thoughts?

rayaans · December 23, 2015

General consensus is it doesn't make any difference performance wise unless your ECU can adapt to it which I highly doubt

Usually the only reason to use it is the additives which will keep the engine clean and the car will feel smoother over a period of time, about 1 year of use on every 4 fills

Sparks16 · December 24, 2015

Just filled up with 'super' for the first time and the mpg has gone down ? Over first 80 miles - going to see how it goes but I reckon it won't make a difference. I was with the dealer yesterday and said various threads on this forum mentioned mpg and that it wasn't as stated in the UK "sales" bumf. He said the 56 / 59 it quotes was a "Government" figure and to view the Lexus American website for a true mpg figure - which as we all know is about 36 / 38.

Goggy · December 24, 2015

All manufactures say that, blame the Government. However, the manufacturers do the test themselves using Government guidelines that can be, and are, abused by all manufacturers. The guidelines are due to be changed in 2017 I think, to produce more accurate figures, although now the manufacturers are saying that date can't be met. The fact they have known about it for several years seems to fall on deaf ears. The recent VW scandal may force it through now though, but if they can get out of it they will.

Yes, the USA figures are much more accurate, so if they can do it, so can the UK and Europe. Or check http://www.fuelly.com

I think Rayaan has it right. it appears that using Super does help clean the engine to help it run smoother, and it is supposed to increase MPG very slightly, about 5%, so the same increase in cost. I will try using it once every 4th fill up and see how it goes. I'll report back.

wh05apk · December 24, 2015

If you think it helps it probably will do, but as far as I am concerned there is minimal difference, petrol is petrol to most cars, and they can't tell the difference, so any difference is purely in the mind if the driver.

PCM · December 24, 2015

But then again, it is Christmas, so maybe a gift for your car?

A full tank of super...

:hohoho:

andyk134 · December 25, 2015

So why are there different octanes sold if it doesnt make a difference then? Is it really just a monumental con as suggested? Should it be investigated?

For me i have always used v power and always will because i do know my car very well and it definitley runs better when i do. I am really not concerned about mpg as it is a drop in the ocean compared to depreciation, so people who buy a new car based on the mpg really don't look at the bigger picture and I always find it amusing when it is discussed! once you drive your new car off the forecourt you might just as well throw wads of cash out of the window as the value drops, so an extra couple of £ when you fill up is hardly relevant.

alanc745 · December 25, 2015

Some performance engines are tuned to run on it, my Smart Roadster is from manufacture designed to run on it.

Giving better performance & fuel consumption, but most cars do not benefit greatly to its use.

There are no more additives in the super unleaded to standard its just a higher octain level, so no cleaner for your engine.

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rayaans · December 26, 2015

Some performance engines are tuned to run on it, my Smart Roadster is from manufacture designed to run on it.

Giving better performance & fuel consumption, but most cars do not benefit greatly to its use.

There are no more additives in the super unleaded to standard its just a higher octain level, so no cleaner for your engine.

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That's not strictly true. Although super unleaded is higher octane, some brand do have a lot more additives insid compared to their normal counterparts. Examples are BP super unleaded and Shell V Power

rayaans · December 26, 2015

Let's not forget Lexus runs on regular gas in the US and the engines are the same so they would probably run fine on 87 octane if available in the UK

ColinBarber · December 28, 2015

Nearly all Toyota engines can adapt to 97 RON fuel so after one or two tanks you should see a slightly improved mpg compared to using standard unleaded available in the UK. The price different between the two fuels normally means the extra mpg doesn't offset the extra cost so I don't personally bother with it.

Certainly higher performance fuels do contain additional cleaning agents. That potentially may be of benefit of the normal fuels you use don't do enough to keep the engine clean (most do).

alanc745 · December 28, 2015

Tesco Unleaded Momentum is 99 Ron but does not pretend to clean your engine, only Shell offer a 99Ron alternative.

Always us Tesco Momentum in my Roadster as it is designed to run on 97 Ron upwards.

Not sure what people's engineering backgrounds are on here or how many realise that all engines in modern cars are designed to burn fuel cleanly!

So the need for additional so called clean fuels with cleaning additives with is not really going to benefit.

There is always some people who are taken in by the marvelous marketing to sell the supposing top fuels with all the snake oil additives.

If they were so good & required by your car it would be listed as the preferred fuel to use in the hand book to maintain your engine in peak Condition.

But surprise surprise it does not.

Everyone is entitled to their own opinion, but please do your homework before you get suckered in!

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rayaans · December 29, 2015

Tesco Unleaded Momentum is 99 Ron but does not pretend to clean your engine, only Shell offer a 99Ron alternative.

Always us Tesco Momentum in my Roadster as it is designed to run on 97 Ron upwards.

Not sure what people's engineering backgrounds are on here or how many realise that all engines in modern cars are designed to burn fuel cleanly!

So the need for additional so called clean fuels with cleaning additives with is not really going to benefit.

There is always some people who are taken in by the marvelous marketing to sell the supposing top fuels with all the snake oil additives.

If they were so good & required by your car it would be listed as the preferred fuel to use in the hand book to maintain your engine in peak Condition.

But surprise surprise it does not.

Everyone is entitled to their own opinion, but please do your homework before you get suckered in!

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No engineering here at all. Completely opposite field of work but don't forget that direct injection engines without injector cleaning systems such as port injection will benefit from additional additives on a regular basis

If I'm not mistaken....... The IS has an inline direct injection engine but I can't remember whether it has port injection

The IS250 suffered from carbon build up, so do most naturally aspirated cars without injector cleansing systems. A lot of NA Audi's like the older RS4, S6 etc suffer from it

Goggy · December 29, 2015

All a bit technical for me. As I mentioned, I will try it out and see if it makes any difference. I doubt I will notice any difference myself, but I will try it anyway, the extra cost is so small it's not worth worrying about.

Nelsthebass · December 29, 2015

If I'm not mistaken - as all engines work on a closed loop principal that leans or riches up the mixture according to load and driving style, I'm sure they will also adjust to different RON fuels too and it maybe that they can run leaner as a result on higher octane fuel and thereby show some increase in mpg?

DanD · December 30, 2015

Has anyone ever had any problems due to using 95 Ron only in their car?

I cover between 20k and 25k miles per year, and I have never ever had any problem related to the type of petrol I use. In fact I tend to use supermarket petrol most of the time with no ill effect.

The manufacturer recommends 95 Ron, so I stick to 95 Ron. Unless your car specifically requires 98 Ron, I am not sure you will notice any difference.

rayaans · December 30, 2015

Has anyone ever had any problems due to using 95 Ron only in their car?

I cover between 20k and 25k miles per year, and I have never ever had any problem related to the type of petrol I use. In fact I tend to use supermarket petrol most of the time with no ill effect.

The manufacturer recommends 95 Ron, so I stick to 95 Ron. Unless your car specifically requires 98 Ron, I am not sure you will notice any difference.

Doesnt apply to RX as much as its not direct injection. Also petrol cars can burn through pretty much anything but I know for a fact supermarkets use crap fuel as diesels are more sensitive and the merc had problems with supermarket fuels. It'd have issues at around 3k rpm

Nelsthebass · December 30, 2015

Latest fil up on "standard" supermarket fuel dropped it down to 35mpg - I'll stick with slightly more expensive branded fuels or cheap super at supermarkets in future.......

andyk134 · December 30, 2015

as many have said its about whether you feel you get a difference. I know that when i used "standard" unleaded the pick up and smooth acceleration was not as good as when i used v power, so thats why i use it. As for cost, you drive a new car off the forecourt and you have lost more in depreciation than it would have cost you in 5 years for the extra cost of using "super" fuel anyway. Supermarket fuels have no additives whatsoever and some call it hype, but whatever it is my car definitely runs better on v power and I have had my car 6 years so I know who it feels.