98 RON (or 99) Fuel

[Robinlarge]

Hi foks - I'm new to my Mercedes CLS C63 (2013) but not new to performance cars. I know the subjetc of fuel comes up time after time but its also something that changes as the years go by.

So ..... My X218 says on the tin that it needs RON 98 - I'm good with that and accept that 99 RON wont do any better, but 95 will probably default the ECU to lower power settings (or just produce a little less power)

There is however a cost/benefit trade off and my question is, after considering Tesco Momentum, Shell V Power, BP Ultimate, Sainsbuy Super Unleaded etc . which one should I use?

The reading so far seems to show that BP isn't worth the money and real world tests show it as maybe a little 'variable' so I am coming down to Shell V Power or Tesco Momentum or Sainsburies Super Unleaded,

Any thoughts (I, sure there will be!)

[Big Brin]

I tend to use Shell V Power 98 RON when I am feeling flush, but more often than not use the standard Shell 95 RON. I use Shell because IMHO the Shell brand represents top quality....however, tbh I also use the 95 or 97 RON at Esso. In the real world I cannot tell any difference.....

Regards, Brin

[Robinlarge]

I plan on using, or rather continuing to use a premium fuel at 97, 98 or 99 RON - but there are differences and these are generally subjective and can be influenced by the engine in question - so wondered if any 5.5L Merc Twin Turbo chaps had any views on which fuel?

So far I have only run one tank of Sainsbury Super 97, now onto BP Momentum to compare. Difficult to be objective though as my driving styles and roads vary from day to day and tank to tank - so may just take a while to settle on one or the other.

[Dave3166]

I use Tesco momentum 95% of the time.

Shell V-Power when feeling happy with life😂

2013 C63 AMG V8 by the way.

[StephenP]

My 2009 CL63 (the normally aspirated engine) has used Shell V-Power (99) or more often Tesco Momentum (99) for most of its 111k mile life. Occasionally gets Sainsburys premium (97) when no Shell or Tesco nearby.

Never has 95 and never will. Can't really understand why anyone would with these cars stipulating 97 minimum and 95 only when there is absolutely no other option (and will give reduced performance).

I guess its down to trying to run one on a tight budget and each to their own of course, but to be honest I'd run a mile from a used RON98 spec AMG if I found it had been running 95.....

Edited by StephenP on Sunday 10th November 11:53

[cuprabob]

StephenP said:

My 2009 CL63 (the normally aspirated engine) has used Shell V-Power (99) or more often Tesco Momentum (99) for most of its 111k mile life. Occasionally gets Sainsburys premium (97) when no Shell or Tesco nearby.

Never has 95 and never will. Can't really understand why anyone would with these cars stipulating 97 minimum and 95 only when there is absolutely no other option (and will give reduced performance).

I guess its trying to run one on a tight budget but to be honest I'd run a mile from a used RON98 spec AMG if I found it had been running 95.....

[vpr]

I don’t thing 95 will do it any harm tbh.

There are countries that don’t do anything more than 95.

[StephenP]

vpr said:

I don’t thing 95 will do it any harm tbh.

There are countries that don’t do anything more than 95.

As I said, each to their own. Personally won't put 95 in
mine though

Edited by StephenP on Sunday 10th November 12:57

[StephenP]

cuprabob said:

StephenP said:

My 2009 CL63 (the normally aspirated engine) has used Shell V-Power (99) or more often Tesco Momentum (99) for most of its 111k mile life. Occasionally gets Sainsburys premium (97) when no Shell or Tesco nearby.

Never has 95 and never will. Can't really understand why anyone would with these cars stipulating 97 minimum and 95 only when there is absolutely no other option (and will give reduced performance).

I guess its trying to run one on a tight budget but to be honest I'd run a mile from a used RON98 spec AMG if I found it had been running 95.....

?

[cuprabob]

StephenP said:

?

Sorry, finger trouble

I was going to say, it would be difficult to know when buying a used car what fuel was used, irrespective what the seller says.

[StephenP]

cuprabob said:

Sorry, finger trouble

I was going to say, it would be difficult to know when buying a used car what fuel was used, irrespective what the seller says.

A very valid point, bit like the oil and other fluids I guess

I probably should have said if the owner happened to mention using 95...

[gizlaroc]

The timing is retarded greatly on that engine, you will lose around 50hp and 10% in mpg, so no saving to be had and you're restricting your car.

99 Tesco is fine and probably the same price as 95 Shell.

[vpr]

I usually run 98/9 in everything inc my garden equipment but occasionally 95 and I notice zero difference, not even on fuel economy.

These cars in CL63 5.5, Various Aston V12’s and V8’s plus more.

Point being it will not harm your engine, it will not have any lasting effects. I reckon there’s a lot of over reacting

[StephenP]

vpr said:

I usually run 98/9 in everything inc my garden equipment but occasionally 95 and I notice zero difference, not even on fuel economy.

These cars in CL63 5.5, Various Aston V12’s and V8’s plus more.

Point being it will not harm your engine, it will not have any lasting effects. I reckon there’s a lot of over reacting

My old Aston V8V and current V12 plus my old C215 CL55 all listed 95 as the correct fuel (and I doubt putting super in make an difference with them) whereas my C216 CL63 clearly states in the manual not to use 95 unless there's absolutely no alternative and the filler cap states 97 minimum so personally I'm happy to go 95 on everything else but 97/99 on with the CL.

It may be because the M156 6.2L V8s have a compression ratio of 11.3:1 compared to the later 5.5L bi-turbos 10:1 maybe? It could just be that the later engine is happy with 95?

[vpr]

Fair point. I maybe should have used the SLS as an example. Last year through France and Italy where often high octane wasnt available id use 95.

Would like to see a power and economy test made

[StephenP]

I have noticed significant performance differences in the US though between regular and premium. We often have a rental GL450 (the petrol V8) and it certainly sounds and drives much better when I put in the fuel is states in the manual vs what I suspect most renters put in ....