Which grade of fuel should be used in AMG's?

[Bobby Dazzler]

Lol, good one. But that's exactly what I said tho in a previous post: direct injection causes carbon build up because the fuel doesn't see the intake track (hence that argument is null for DI engins). I'm talking (or others are) about carbon on the valves as shown in the shell interview... I just don't think that exists any more. Where are the forum posts bemoaning their AMG or Ferrari has had to have a head strip down? Never happens. Stopped happening circa 1976 i reckon . Plus if it was an issue, why use supermarket petrol even if it was 99 ron?

Most M156 engines have top end rebuilds at around 100-120k miles, either preventatively or to fox issues. Granted it’s not necessarily due to carbon build up, but it’s commonplace and one of the things that puts would-be M156 owners off!

 

[Bobby Dazzler]

I’m pretty sure your car will require super unleaded. The car is clever enough to protect itself from damage whilst running 95 RON fuel; but there’s no need to take that risk - nor limit performance - when Tesco 99 RON is a small premium over 95 RON. In fact you may find that Tesco 99 RON is the same as 95 RON in other filling stations, depending upon your loca market conditions.

When I posted the above I incorrectly assumed that you had an M157 equipped E 63 AMG.

 

[Sparkee]

Were these identical engines? Run on supermarket super unleaded or oil company super unleaded?

Identical engines and the super run one was v power only.
I'm not a mechanic but it was clear as day that the super run one was much cleaner.

 

[philnewmerc]

Identical engines and the super run one was v power only.
I'm not a mechanic but it was clear as day that the super run one was much cleaner.

And the 95 one was Shell as well or supermarket fuel?

 

[ALFAitalia]

I'm being asked to do one at the moment...followers, VVT plates and head bolts. Not sure if I'm going to, to be honest.....no time. But hes at about 120,000 miles and to be honest the owner is a bit of a worrier. He says the top end is noisy.....but they were never that quiet when new and it sounds pretty normal to me. The injectors have already been done twice and the oil changed at a max of 5000 miles! I've told him to listen to a few others....as good as they are they are old tech and mechanically more vocal than modern engines.

 

[Sparkee]

And the 95 one was Shell as well or supermarket fuel?

They said it had never seen super, other than that no idea

 

[philnewmerc]

They said it had never seen super, other than that no idea

In that case it's anyone's guess if this was due to 98 vs 95 (unlikely) or oil brand vs supermarket brand (possible) or just different owners with different riding styles and maintenance (most probable imho).

 

[ALFAitalia]

Both the first two should be labelled "unlikely" these days imo...all supermarket fuels have additives and detergents in these days...it's not 1984!

 

[philnewmerc]

Both the first two should be labelled "unlikely" these days imo...all supermarket fuels have additives and detergents in these days...it's not 1984!

I wouldn't say supermarket fuel was bad at all but the oil producer's petrol will have the best/latest additives, if only slightly. It might only be a tiny bit better but if the cost is virtually the same i see no point in using 'own brand' petrol. Like Tesco own brand jam vs Bonne maman jam. Fairy liquid Vs Tesco washing up liquid. Or Shell 10w40 vs Tesco 10w40. Am sure it'll be perfectly adequate but supermarkets and oil companies are there purely for profit and the oil companies don't give their rivals the best/latest additive packages, just a perfectly adequate one.

 

[Bobby Dazzler]

I wouldn't say supermarket fuel was bad at all but the oil producer's petrol will have the best/latest additives, if only slightly. It might only be a tiny bit better but if the cost is virtually the same i see no point in using 'own brand' petrol. Like Tesco own brand jam vs Bonne maman jam. Fairy liquid Vs Tesco washing up liquid. Or Shell 10w40 vs Tesco 10w40. Am sure it'll be perfectly adequate but supermarkets and oil companies are there purely for profit and the oil companies don't give their rivals the best/latest additive packages, just a perfectly adequate one.

That’s a very similar logic as to why almost everyone else in this thread uses super unleaded.

They wouldn't say 95-RON fuel was bad at all but the 99 RON petrol will have the best knock resistance and best/latest additives, if only slightly. It might only be a tiny bit better but if the cost is virtually the same they see no point in using 95 RON petrol. Like Tesco own brand jam vs Bonne maman jam. Fairy liquid Vs Tesco washing up liquid. Or Shell 10w40 vs Tesco 10w40. They’re sure it'll be perfectly adequate but supermarkets and oil companies are there purely for profit and the oil companies don't give the 95 RON the best/latest knock resistance and additive packages, just a perfectly adequate one.

 

[Bobby Dazzler]

That’s a very similar logic as to why almost everyone else in this thread uses super unleaded.

They wouldn't say 95-RON fuel was bad at all but the 99 RON petrol will have the best knock resistance and best/latest additives, if only slightly. It might only be a tiny bit better but if the cost is virtually the same they see no point in using 95 RON petrol. Like Tesco own brand jam vs Bonne maman jam. Fairy liquid Vs Tesco washing up liquid. Or Shell 10w40 vs Tesco 10w40. They’re sure it'll be perfectly adequate but supermarkets and oil companies are there purely for profit and the oil companies don't give the 95 RON the best/latest knock resistance and additive packages, just a perfectly adequate one.

Of course the logic why almost everyone in this thread uses super unleaded is also very slightly different. And that’s because the manufacturer of their car states that can only use an own brand alternative when Bonne Maman jam is not available. I mean Fairy Liquid. I mean Shell oil. I mean super unleaded petrol

 

[Will]

I wouldn't say supermarket fuel was bad at all but the oil producer's petrol will have the best/latest additives, if only slightly. It might only be a tiny bit better but if the cost is virtually the same i see no point in using 'own brand' petrol. Like Tesco own brand jam vs Bonne maman jam. Fairy liquid Vs Tesco washing up liquid. Or Shell 10w40 vs Tesco 10w40. Am sure it'll be perfectly adequate but supermarkets and oil companies are there purely for profit and the oil companies don't give their rivals the best/latest additive packages, just a perfectly adequate one.

Would you buy Tesco own brand jam or own brand washing liquid if it was only 6/7p cheaper though?

And that’s ignoring the risk of damage not just a perceived quality perspective.

At the end of the day by using 95RON fuel you’re using the wrong fuel, it doesn’t meet the correct specifications. Sure in an emergency if you physically can’t get the correct fuel it will allow you to keep going but to actively choose to do so just doesn’t seem to make any sense especially when the cost of correct spec fuel isn’t that much different anyway?

Seems a massively over complicated thread for what is essentially a no-brainer IMHO

 

[Bellow]

Rpm and load together need octane. Peak load at peak rpm is highest stress. More of either risks pinging.

Nope. High rpm engines do not have the same dependency on octane as lower rpm motors. Race bike engines of the 1960s turning 17-18000 rpm only needed octane of circa 60. The same as paraffin.

Does anyone hear knocking on their mb that goes away using 98 ron?

You'll never hear it. The knock sensors are too fast for that.

I think you're imagining 'retarded' meaning several degrees over tdc which would indeed have the effect of causing still-burning fuel to wizz past the exhaust valves.

Nope, I'm imagining nothing.
Later ignition timing still delivers complete combustion - but the fuel efficiency suffers. And does so because the heat is realised too late for maximum expansion and thus work at the crank. That unexploited heat goes somewhere. Down the pipe is where it goes, roasting exhaust valves as it does and putting more heat into the cats than is welcome.

But this is not a 1976 suped up Cortina, it is a massively advanced enging and the retardation go run on 95 is tiny...

Modern day engines are much more sensitive to this. I have the burned exhaust valves to prove it - from the engine with Engineered by Mercedes-Benz emblazoned on it. Mercedes-Benz - not FoMoCo.

 

[ALFAitalia]

That’s a very similar logic as to why almost everyone else in this thread uses super unleaded.

They wouldn't say 95-RON fuel was bad at all but the 99 RON petrol will have the best knock resistance and best/latest additives, if only slightly. It might only be a tiny bit better but if the cost is virtually the same they see no point in using 95 RON petrol. Like Tesco own brand jam vs Bonne maman jam. Fairy liquid Vs Tesco washing up liquid. Or Shell 10w40 vs Tesco 10w40. They’re sure it'll be perfectly adequate but supermarkets and oil companies are there purely for profit and the oil companies don't give the 95 RON the best/latest knock resistance and additive packages, just a perfectly adequate one.

I bet the differences between those products is much greater than the differences between super market fuel and big brand fuel. There is lots of stuff on the net......never seen an independent tesr where they found the super market fuel in any way inferior....as long as it's the same octane it's basically exactly the same fuel made in the same place.
And to suggest the 95 gets an inferior additive pack to the 98 or 99 is silly too....why would they? Detergents etc are just as required in the 95 stuff. None that I can see even claim that....it's just the octane (the most important bit after all) that varies.

 

[Iggu]

Would you buy Tesco own brand jam or own brand washing liquid if it was only 6/7p cheaper though?

And that’s ignoring the risk of damage not just a perceived quality perspective.

At the end of the day by using 95RON fuel you’re using the wrong fuel, it doesn’t meet the correct specifications. Sure in an emergency if you physically can’t get the correct fuel it will allow you to keep going but to actively choose to do so just doesn’t seem to make any sense especially when the cost of correct spec fuel isn’t that much different anyway?

Seems a massively over complicated thread for what is essentially a no-brainer IMHO

Agree. Just get a Shell V-Power loyalty card and put nowt else in.

 

[Bobby Dazzler]

And to suggest the 95 gets an inferior additive pack to the 98 or 99 is silly too....why would they? Detergents etc are just as required in the 95 stuff. None that I can see even claim that....it's just the octane (the most important bit after all) that varies.

Shell don’t claim to use different detergents and cleaning agents in VPower, but they imply that there’s more of them by saying that there are three times as many molecules, which is an interesting - and surely deliberate - way of saying it!

Shell V-Power Unleaded

Introducing our latest-generation Shell V-Power Unleaded fuel, contains 3x more cleaning molecules than Shell our regular Unleaded. Find out more here.

www.shell.co.uk

 

[sgregory124]

It’s relatively recent - probably the last 18 months or so.

And costs a ridiculous amount too, at least when I had the misfortune to need a fill up….

 

[Bobby Dazzler]

And costs a ridiculous amount too, at least when I had the misfortune to need a fill up….

I forget now but the mark up was closer to VPower tha. momentum. It’s helpful to have another 99-RON option especially when driving in less urban areas.

 

[geoffus]

A strip down on 2 engines, one only run on super and one only run on 95 showed high build ups off deposits in the 95 and hardly any in the super one.
That £5 extra a tank is like adding a bottle of cleaning additive every fill up.

“ and explain what 15k mile of cheapo can do to a engine.“

A high build up after 15k miles using 95 fuel, which also contains cleaning additives, I think someone is telling you porkies.

 

[philnewmerc]

That’s a very similar logic as to why almost everyone else in this thread uses super unleaded.

They wouldn't say 95-RON fuel was bad at all but the 99 RON petrol will have the best knock resistance and best/latest additives, if only slightly. It might only be a tiny bit better but if the cost is virtually the same they see no point in using 95 RON petrol. Like Tesco own brand jam vs Bonne maman jam. Fairy liquid Vs Tesco washing up liquid. Or Shell 10w40 vs Tesco 10w40. They’re sure it'll be perfectly adequate but supermarkets and oil companies are there purely for profit and the oil companies don't give the 95 RON the best/latest knock resistance and additive packages, just a perfectly adequate one.

Except it doesn't cost virtually the same, it's 70p a gallon more. If you buy fuel from shell BP etc near a supermarket it'll be identical or v close in price.