super unleaded ???

[00slk]

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

There'd be a lot of pi"%ed cars on the road

 

[John Laidlaw]

There'd be a lot of pi"%ed cars on the road

They'd be happy though!

 

[A.J.]

There'd be a lot of pi"%ed cars on the road

That coupled with pi"%ed drivers !!

 

[alexanderfoti]

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.

Other way round. The car will have a base timing map and will then pull timing if it detects knock. Most of the na engines from mb are tuned for 95 Ron, their turboed cars/AMG stuff is 98 Ron.

The MB timing maps are pretty conservative for UK Shell 99 Ron and you can safely add 1-2 degrees without any knock.

 

[LostKiwi]

Looking in the r230 500SL manual the fuel recommended is 96RON. I doubt you'd notice anything running 95RON.

 

[Craiglxviii]

The gold coloured plating would have been burnt off by the greater combustion temperatures reached using the higher octane rated fuel. Similarly the lack of sooting is because the higher temperatures caused it to be scavenged off.

By the way, I'd challenge the assertion that supermarkets' expertise lies in food. I would say that it lies in customer service, and thus any issues with contaminated fuel would be more likely jumped on and fixed quickly than with a fuel manufacturer. Sainsbury's don't want to risk adverse publicity as that impacts them across the board for instance.

On the cost per mile, don't underestimate the subconscious effect. "This fuel costs more/ this fuel will deliver better fuel efficiency" directly translates into a slightly altered driving style. Your right foot has more effect on fuel efficiency than anything else you can do...

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]

The gold coloured plating would have been burnt off by the greater combustion temperatures reached using the higher octane rated fuel. Similarly the lack of sooting is because the higher temperatures caused it to be scavenged off.

By the way, I'd challenge the assertion that supermarkets' expertise lies in food. I would say that it lies in customer service, and thus any issues with contaminated fuel would be more likely jumped on and fixed quickly than with a fuel manufacturer. Sainsbury's don't want to risk adverse publicity as that impacts them across the board for instance.

On the cost per mile, don't underestimate the subconscious effect. "This fuel costs more/ this fuel will deliver better fuel efficiency" directly translates into a slightly altered driving style. Your right foot has more effect on fuel efficiency than anything else you can do...

Just like having a clean car tends to make you drive more carefully and probably more fuel efficiently ....the power of the subconscious is an amazing thing !

 

[om613]

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.

The ethanol content did it.

 

[Chrishazle]

OM613, you're upside down on the ethanol content, as 95RON petrol can be up to 10% ethanol (E10) especially on the continent, whereas UK 98/99RON will be no more than 5% ethanol (E5). Owners of pre-1996 Porsches are pretty clued up on this, as our cars have a rubber lining on the fuel lines that will not tolerate 10% ethanol so we have to be very careful, especially on the continent where I have even seen an E10 sticker on a 98RON pump (in Northern Spain).

 

[Submariner1]

The gold coloured plating would have been burnt off by the greater combustion temperatures reached using the higher octane rated fuel. Similarly the lack of sooting is because the higher temperatures caused it to be scavenged off.

By the way, I'd challenge the assertion that supermarkets' expertise lies in food. I would say that it lies in customer service, and thus any issues with contaminated fuel would be more likely jumped on and fixed quickly than with a fuel manufacturer. Sainsbury's don't want to risk adverse publicity as that impacts them across the board for instance.

On the cost per mile, don't underestimate the subconscious effect. "This fuel costs more/ this fuel will deliver better fuel efficiency" directly translates into a slightly altered driving style. Your right foot has more effect on fuel efficiency than anything else you can do...

I would conceed that point and it wasnt that scientific in that I didnt compute any factor for changing fuel prices ... that in fairness could blow the whole exercise out of the water.
But globally it didnt seem to cost any more.

At the time I had a £11,500 pa car allowance and they paid all the business petrol .. so it didnt really matter to me then.
Now is different lol
Penalty of retiring early :-/

The way these tossers are negotiating Brexit .. with hindsight I should have continued as this gutless route will decimate us financially.

Political content removed.

 

[Craiglxviii]

True, but that has little to do with octane ratings and there is a Brezit thread...

 

[LostKiwi]

I had to check the thread title there....

 

[Craiglxviii]

I had to check the thread title there....

Holy thread drift Batman!

 

[teddycatkin]

It makes me smile when people pay £10000'S of pounds for thier prized MB and the want to put cheapest fuel in them ???

 

[LostKiwi]

It makes me smile when people pay £10000'S of pounds for thier prized MB and the want to put cheapest fuel in them ???

It makes me smile when people pay £10,000s of pounds for their prized MB then want to put any random mix of additives in the tank or sump???

At least even the cheapest fuel has to meet a basic standard.

 

[John Laidlaw]

It makes me smile when people pay £10,000s of pounds for their prized MB then want to put any random mix of additives in the tank or sump???

At least even the cheapest fuel has to meet a basic standard.

Or when they want to put Renault Kangoo brake pads on an AMG E63...

 

[Craiglxviii]

Or when they want to put Renault Kangoo brake pads on an AMG E63...

<cof cof>

 

[s5tuart]

I always put the best in. Helps keep my smugness levels high!

 

[Yugguy]

Filled up with ultimate diesel ans I swear the car is quieter. I need to get the missus to fill up a couple of times and not tell me and do a blind test.

 

[Frosty149]

Filled up with ultimate diesel ans I swear the car is quieter. I need to get the missus to fill up a couple of times and not tell me and do a blind test.

If it works on the missus ,
I want - no need, some
at any price!!!