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

[Bobby Dazzler]

But mamy would say using supermarket fuel is running it on the cheap!

I wouldn’t worry what those people say. Firstly because I simply wouldn’t worry what people say, and secondly they don't know much about fuel or engines if they hold that (misguided) belief about Tesco Momentum.

 

[Bobby Dazzler]

I’ve been a staunch user of VPower for many years - even VPower diesel - however very recently it has become much more difficult to justify. When it was a 7p premium for super and about 5p for Shell over supermarket regular unleaded then I wouldn’t think twice and would drive a looooooooong way to get VPower.

Now that the cost differential is so great between VPower and Tesco Momentum then I’ll fill up with whichever of those two is most convenient. It’s rare that I’m not close to either Momentum or VPower, but on that very rare occasion then I use Esso now they have 99 RON. I avoid everything else - including 97 RON - unless an emergency.

 

[Spider10]

Ive not even checked the SLK55 AMG it gets 99 RON end of story and don't ask what it does to the gallon as ive never looked probably the same as the M156

 

[Steve84N]

For an engine designed to use 98 then the extra cost is at least partially offset by better mpg than 95.

 

[geoffus]

Had a mx5 for a good while, you could tell the difference in the fuels in that. It liked v power the most, tesco or esso super after that. It most definitely didn't run as well on cheap unleaded.

Not to mention the super types all contain extra detergent stuffs that help prevent build up. Had an mx5 racing team do demos and explain what 15k mile of cheapo can do to a engine.

What did did they say using the recommended 95 Ron fuel would do to the MX5 engine ?
I’ve run my R1 on V power and Tesco 95 and never noticed any difference, it was designed for 95.

 

[ALFAitalia]

Esso Synergy Supreme 99plus is sold as E5..but it's actually E0 (ethanol free) in most parts of the country.

 

[Skd884]

What consequences though? It's a modern ecu controlled knock detection engine, the only consequence i can see is less power (not detectable to me) and maybe less mpg (but i haven't noticed that either) and perhaps issues if you were on a track day due to continuous high temperature running. Any reports of issues arising from 95 ron fuel in normal use? Only issues i can see on searches is using supermarket fuel rather than oil company brand... Remember MB also said gearbox oil is filled for life so I'm not 100% convinced by their info. Happy to see evidence to the contrary but if half of Mbclub are using 95 and no issues then it does make me wonder if 98 is overkill.

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[Iggu]

I’ve been a staunch user of VPower for many years - even VPower diesel - however very recently it has become much more difficult to justify. When it was a 7p premium for super and about 5p for Shell over supermarket regular unleaded then I wouldn’t think twice and would drive a looooooooong way to get VPower.

Now that the cost differential is so great between VPower and Tesco Momentum then I’ll fill up with whichever of those two is most convenient. It’s rare that I’m not close to either Momentum or VPower, but on that very rare occasion then I use Esso now they have 99 RON. I avoid everything else - including 97 RON - unless an emergency.

Agree with this. I didn’t know Esso did a 99 now though. Good to know.

 

[Bobby Dazzler]

Agree with this. I didn’t know Esso did a 99 now though. Good to know.

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

 

[philnewmerc]

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"Carbon on the valves" was a problem that afflicted engines up to the 60/70s. If you can link to an AMG owner (or any other modern engine for that matter) who has had to have a rebuild due to that I'd delete my account. As for Gordon Murray or Ferrari choosing Shell, well of course they do, it's a business deal and could just as easily have been Esso or BP. I'm not saying these fuels don't have good detergent qualities, I'm sure they do, which is why I'd normally avoid Tesco or other supermarket fuel - yet lots of AMG owners like supermarket Tesco fuel because they do cheap 99 ron. Fair enough but I think I'd tend to value extra cleaning power of an oil company branded 95 ron fuel over a few bhp because of extra octane in 99 ron Tesco supermarket fuel. (Unless it was bad to use 95, but no one has linked to a damaged engine link.)
NB if your car has direct injection then the cleaning power explained by the shell rep no longer works... This is a known problem.
NB2 i am a contrarin and just arguing the toss here

 

[philnewmerc]

Esso Synergy Supreme 99plus is sold as E5..but it's actually E0 (ethanol free) in most parts of the country.

A very good reason to use in older cars and motorcycles. My guzzi definitely is nicer throttle response on it

 

[philnewmerc]

For an engine designed to use 98 then the extra cost is at least partially offset by better mpg than 95.

If that was true I'd be a no brainer... Never detected a difference my self though

 

[Sparkee]

What did did they say using the recommended 95 Ron fuel would do to the MX5 engine ?
I’ve run my R1 on V power and Tesco 95 and never noticed any difference, it was designed for 95.

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.

 

[ALFAitalia]

Carbon on the valves" was a problem that afflicted engines up to the 60/70s. If you can link to an AMG owner (or any other modern engine for that matter) who has had to have a rebuild due to that I'd delete my account.

Well its been nice knowing you! Nearly all modern direct injection engines suffer with carbon build up on the intake valves. Where the fuel does not pass the intake valves inn modern motors there is no fuel to keep thelr backs clean...that combined with egr valves letting oily air into the air intake which burns onto the back of the valves ruins air flow into the engine. It's gets to the point that the intake ports become so blocked with black sticky baked on carbon that they become difficult to start. Yeah I know you meant carbon build up on the valves inside the combustion chambers and on the valve seats preventing the valves closing....but carbon on the valves is carbon in the valves!
I only recently had to rebuild the head of petrol 2.2 ALFA 159 for just this reason. Of course in the case of this problem it will happen no matter what grade of fuel you use.

 

[RJ C63]

A very good reason to use in older cars and motorcycles. My guzzi definitely is nicer throttle response on it

Synergy Fuels | Esso

Esso branded service stations have a variety of Synergy fuel blends (grades) to help you get to where you're going. Learn more here.

www.esso.co.uk

Esso 99 will be 5% ethanol from next month...

 

[ALFAitalia]

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.

That's down to the additives added...not the octane rating of the fuel....the both have roughly the same amount of carbon in. 95 and 99 with the same additive packs would burn equally as clean. You would get way more variation between two engines run on the same fuel....with one pooddled around and the other driven properly and given the old Italian time up once in the while!

 

[philnewmerc]

It isn't rpm that demands octane.


Where the torque is is where the detonation risk is and where octane is required.


The retarded ignition timing the ECU imposes when detonation is sensed leaves more heat in the exhaust stream which is hard on exhaust valves. Not necessarily catastrophically so, but not entirely benign either.
Hotter exhaust valves increase the detonation risk imposing further retardation of ignition timing - and on it goes.

Give it the octane it was designed for as specified by the manufacturer.

Rpm and load together need octane. Peak load at peak rpm is highest stress. More of either risks pinging. Does anyone hear knocking on their mb that goes away using 98 ron?
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. But this is not a 1976 suped up Cortina, it is a massively advanced enging and the retardation go run on 95 is tiny...

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.

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

 

[Bobby Dazzler]

@philnewmerc I’ve just looked at your profile and it mentions a CLS 55, in which case your car was almost certainly designed to use 95 RON but has a knock detecteot and so can offer improved performance with higher octane super unleaded fuel. Check the sticker on the inside of your fuel filler flap to be sure.

 

[philnewmerc]

Well its been nice knowing you! Nearly all modern direct injection engines suffer with carbon build up on the intake valves. Where the fuel does not pass the intake valves inn modern motors there is no fuel to keep thelr backs clean...that combined with egr valves letting oily air into the air intake which burns onto the back of the valves ruins air flow into the engine. It's gets to the point that the intake ports become so blocked with black sticky baked on carbon that they become difficult to start. Yeah I know you meant carbon build up on the valves inside the combustion chambers and on the valve seats preventing the valves closing....but carbon on the valves is carbon in the valves!
I only recently had to rebuild the head of petrol 2.2 ALFA 159 for just this reason. Of course in the case of this problem it will happen no matter what grade of fuel you use.

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?

 

[philnewmerc]

That's down to the additives added...not the octane rating of the fuel....the both have roughly the same amount of carbon in. 95 and 99 with the same additive packs would burn equally as clean. You would get way more variation between two engines run on the same fuel....with one pooddled around and the other driven properly and given the old Italian time up once in the while!

Exactly.

Eeee, i do like a good argument after a beer. Might start an oil thread next