super unleaded ???

[shellnjohn]

Hi there, this is a wife of an new SL 500 owner 2011
Love it and have had loads of fun with hubby and have absolutely enjoyed watching him smile beaming from ear to ear!!!
But we seem to be at the petrol station alot.........
He has only been putting the super unleaded in.....££££
My question is can we use Sainsburys super unleaded??
As we have only been using non supermarket super petrol ie shell or esso...

Can anybody answer this simple question for me.

Many thanks michelle x

 

[LostKiwi]

Absolutely.
I run my SL500 (1993 vintage) on 95 octane from Tesco with no issues. Also use 95 in my E240 and Tesco 98 is the favourite fuel of my modified Smart Roadster (141hp per litre!).

 

[Craiglxviii]

We get asked this a lot. Firstly look in your owners manual, it will specify the fuel octane ratings permissible. You can use 95 RON with no bother. Like LK I too run my CL500 on 95 RON with no problems.

Secondly, what one finds is that most cars do not benefit to a noticeable difference from the higher rates fuel. The engines are not set up to take advantage of it either with piston rings or in the ECU. The whole super fuel thing for non- race tuned cars is really a very clever bit of marketing by the fuel companies.

 

[Frosty149]

+1^
As Craig says, the 'perceived' benefit of paying for higher rated, non-supermarket fuel is largely a placebo effect, imo, brought on by some dubious marketing claims.
In your instance, more expensive fuel is not providing a performance benefit of any significance-a bit of simple maintenance is likely to give you a more significant return.
IMO, enjoy the car whatever...

 

[John Laidlaw]

I ran my SL500 on a mixture of supermarket , oil major, 95,97 or 98 Ron and as said above the 500 n/a lump isn't tuned enough to notice any difference at all, so just use whatever is convenient and cheap!

 

[Big Cheese]

I found I get more MPG when using Tesco super unleaded than the normal stuff in my ML63.
Or I wasn't as heavy with the right foot

 

[John Laidlaw]

Yip I use super in my 63 but that's a different animal, a tuned performance engine - the 500 was quite different

 

[Craiglxviii]

I found I get more MPG when using Tesco super unleaded than the normal stuff in my ML63.
Or I wasn't as heavy with the right foot

With a tuned 63 engine you may very well notice a 4-5% improvement.

You may also be subconsciously less lead- footed as you know the fuel is more costly..!

 

[dreadlockdw]

It seems that every car forum I've ever read has had threads relating to "super" fuels. I believe that the main argument for using them in a "normal" engine are that they include additives which help the engine to run cleaner, and by implication last longer, rather than that they will change the performance in any meaningful way. The problem is that without running control tests and stripping an engine down periodically this is hard to prove.

 

[peterws1957]

The manual on my Cl specifies 98 otherwise dire consequences result with 95 being used as a temporary measure if necessary. For the relatively low mileage it does I dont risk it for the additional cost involved. The manual also refers to not putting deisel in! Nothing like a bit of nannying...

 

[S500 Pete]

I wish there was a definitive answer to this question.
I run my E500 and my wife's Audi TT on super unleaded (mainly Tesco or Costco) and always have.

This goes back to my days running smart. When I was taking it to be remapped the tuner suggested that I fill it with super so that he could set up the map to suit it. He reckoned he could get more HP with the super. There was also an article on the smart website abut 10 years ago where one of the tuners did some testing of mpg over about 3 tankfuls and saw about a 4-5% improvement with Super. Thing is I guess the smart being a turbo was fairly highly tuned straight from the factory.

I would have thought that the Merc ECU is constantly changing the timing to be as far advanced as possible for more power without pinking, in which case super can run more advance and produce more power from the same amount of fuel so better economy.

Would one of the Tuning companies on this forum care to comment

 

[Craiglxviii]

Absolutely true that a custom map can develop more power and/ or better efficiency. The existing factory maps (dependent on manufacturer) will be set up for the lowest expected fuel quality in the market that car is being sold into. VAG for example have 13 different global ECU maps. Some Japanese manufacturers have 2 (Japan, Rest of World). I don't know what MB use but I suspect that they have some "play" in their mapping. In the U.K. we have quite high quality fuels, so the play in the mapping can be tightened up somewhat.

Point made earlier is still true, with a non tuned engine 99 RON will make no difference.

 

[Submariner1]

I would stick to Shell 98.
Why
I was told by Mercedes technical the SL500 R230s will tune themselves to benefit from it. Similarly it will detune itself if you get some crap low octsne petrol in outback Spain.

Interestingly for tax purposes, I had to keep meticulous recods on 4 of the 5 new SL500s I owned.

So it was easy to select on the spreadsheet, cost per mile with 95 and 98. They were surprisingly very close.
I assumed as Shell say it generates 9 or 11% more power ( forget now which one they said) that the 98 octane developed more power, that pretty much cancelled out the extra cost.

Note the excercise on the first SL320 an R129 did not benefit (per my spread sheet) from 98 ... it just cost more ... so I assumed it could not retune itself to take advantage of the higher Octane.
So on the newer ones ... as on balance it cost no more ... why not?

I personally felt they felt "sharper" on 98. But then there is the placebo effect.

More importantly, I run my Honda professsional mower on 98 (only as I cant be bothered having 2 types of petrol in cans).
They are supposed to be decoked annually (probably really for the landscape gardeners running them 24/7) As it costs £275 to have that done ... no way. But after 8 years I had it done. The mechanic called me up and said I should have a look. Blimey the inside if the head and the valves were like polished chrome! Looked brand new.
He showed me other heads ... totally black sooted up with carbon.
So for this reason, it was a no brainer. That top Shell stuff really does clean the engine.

Thirdly supermarkets expertise is in food!
There are less incidents of contaminated petrol in the shell chain than the supermarket chains. So that's a no brainer.

I have had 7 V8s from new ... and fundamentally ran them on 98. Never had an engine problem.

As my CL500 is out of mfg. warranty, and the engine is sooooo expensive. My view is its not worth doing anything but the best for them.

But I do low mileage so the difference in any event would be negligible.

As for visiting the garge a lot ... love that observation
Hmmm welcome to big V8s ... as they say nothing in life is free
Enjoy it !


One possible negative. The inside of Honda carburettors has a sort of flashing, it looks like thin gold plate. When the first mower was run on 95 this plating lasted, it like new for 6 or 7 years. After switching to Shell 98 the plating was gone! On the old and the new mower, that new mower was then only 2 years old. So, I assume this cleaning agent stripped it off.

I am hoping Shell worked with people like Mercedes to make sure nothing in their fuel system was adversely effected.
I only mention mowers as obviously I have never seen inside the Mercs engines.

 

[John Laidlaw]

Hmmmm...wonder where supermarket petrol comes from?
In the UK certainly in the main the Oil refinery loading racks as BP, Shell, Texaco, Gulf.......
I use Sainsbury's 97 Ron Super Unleaded mainly, I know where it comes from and it's an Indian owned refinery very close to where I'm sitting right now....

 

[LostKiwi]

There are less incidents of contaminated petrol in the shell chain than the supermarket chains. So that's a no brainer.

All fuel comes from the same refineries and have 'custom' additive packs added after initial dispatch.
More people buy from the supermarket chains so there will be more incidents not only through more people buying from them but also as they have more frequent replenishments so have a greater chance of being 'delivered bad fuel'. Similarly the more often a tank is opened the more change there is of it not being correctly closed so allowing contamination.
Most contamination is through either poor storage at the end user or user error during delivery.

 

[LostKiwi]

Hmmmm...wonder where supermarket petrol comes from?
In the UK certainly in the main the Oil refinery loading racks as BP, Shell, Texaco, Gulf.......
I use Sainsbury's 97 Ron Super Unleaded mainly, I know where it comes from and it's an Indian owned refinery very close to where I'm sitting right now....

Stanlow perchance?

 

[Submariner1]

Hmmmm...wonder where supermarket petrol comes from?
In the UK certainly in the main the Oil refinery loading racks as BP, Shell, Texaco, Gulf.......
I use Sainsbury's 97 Ron Super Unleaded mainly, I know where it comes from and it's an Indian owned refinery very close to where I'm sitting right now....

I assumed it was more about the maintenance of the petrol, tanks pumps etc.

Sure Sainsburys dont make petrol .. just buy it in.

 

[John Laidlaw]

I assumed it was more about the maintenance of the petrol, tanks pumps etc.

Sure Sainsburys dont make petrol .. just buy it in.

You'd be surprised on that Peter- the supermarkets in general have newer equipment by default, their throughput as LK has mentioned above makes them subject to more scrutiny I guess .
The same throughput makes their equipment maintenance vital, not to mention lossage and accuracy of supply at their end will be under more scrutiny (their margins are tighter)
As mentioned above it's the additives which differentiates the fuel - good or bad- there is for sure some placebo affect
OK I was a bit 'general' earlier- there are some storage companies who hold spot bought fuel for the supermarkets, but again it's coming from rerouted refineries just not in this country

 

[John Laidlaw]

Stanlow perchance?

Is right!

 

[John Laidlaw]

Now if Carlsberg made petrol.......