Normal diesel or posh diesel?

[GeordieNomad]

Ive joined a few MH FB groups and I’ve seen a few posts of the benefits of using the better kind of diesel you can get at petrol stations. Folk claim its better for the van, better mpg etc..
Question is, is there any truth in this?

Cheers

 

[Tonks]

This thread is quite funny when you consider only a few years back everyone was clamouring to buy used chip oil to put in their tanks.. and I know some who still do.

Not quite everyone.

 

[Daffy64]

It doesn't, on petrol the knock sensor feeds the info to ecu and with higher octane it will adjust the ignition timing electronically to avoid pre ignition. This is done very fast, and as soon as 98-99 octane enters combustion, immediately its adjusted by the ecu.
On diesel you have a fixed fuelling map, it’s not adjusted on higher cetane. The only time this can be changed, it’s only when you have a re map.

You’re not wrong but don’t forget the boost and ambient pressure sensors, with a fuel that generates a bigger bang the boost pressure would be bigger, this being the case the ECU or even an old mechanical fuel pump would dial back the fuel load - this being the case all diesels compensate for varying quality fuel - this is how multi fuel engines work, introduce gas to the inlet charge and the ECU dials back the diesel quantity - some see this as a good thing as gas is cheaper than diesel.

Some might find it interesting that modern commercial vehicle engines will know the weight of the vehicle within a few miles, it calculates this from the power output of the engine at any given moment (it knows this too) and how quickly it accelerates.

 

[Steve-N]

I'm sure my stubby 6m, 3.5t A-class deploys parachutes when I start the ignition. Long motorway runs with 60mph on the speedo with cruise control with trucks queuing to pass me. I'll still only get 28mpg fill to fill.

After a while I gave up. I run at 65-70mph and just resign myself to it giving me 26mpg.

Having moved to a new van this year, it has the "new" PSA 2.2 ltr 140hp euro 6 final engine from Fiat (same engine now in all the Ducato derivatives)
On a steady motorway run it hit 42 mpg, and it's now averaging 34 mpg
At long last Fiat has made something hardf decent

 

[Guigsy]

I normally do about 26mpg in my 3.5t a-class. So I was curious and filled up with Shell V-Power a few days ago. I've done 300 miles so far and I'm averaging 29.9mpg. That includes starting in Bedfordshire, M1, half a lap on the M25 in the morning rush hour, a 30 mile detour over the Downs and around East Sussex's back roads to avoid tailbacks in Tunbridge. Return journey the other way around the M25 in the late afternoon to Beds. Then back to Birmingham the next day.