How Premium is Costco Premium Diesel?

shiraz99

Just filled up today at Costco with their so-called "Premium Diesel" but is it really premium in the same way as, for example Shell's Vpower diesel, or is it just.marketing guff. I did have a good look at the pump but all I could see was that is B7 diesel, which afaik is just regular diesel.

400ixl

Diesel is graded by cetane rating.

Costco appear to claim theirs is a minimum cetane rating of 51
Shell V Power claims to be a minimum cetane rating of 56

Suggests it is just the standard rating, but may have more additives than your regular diesel.
 

Bigwheels1111

I use it as I get a card via my friend for £16.80 a year, well until next year.

3 Fill ups a year cover the card cost. Is it premium I do not know.

Its cheaper than standard diesel so I use it.

I add,

Mannol cetane plus 9955

I find that my diesel starts smoother and is quieter and drives off without hesitating.

Gives a few more mpg, but costs £1.80 per tank full.

Mildly_Miffed

Unlike the more expensive petrols, there's zero functional difference with the more expensive diesels.

The only difference is in the brand-specific additive packages added at the cross-brand regional distribution depot to the base fuel - the base fuel is the same for all brands, because it's pipelined from the handful of national refineries.

I bet those who say they can tell the difference wouldn't do so in a double-blind trial.

The more expensive petrols are higher octane - they are more resistant to ignition, which helps prevent pinking, allowing higher compression or more boost. That's irrelevant to the vast majority of cars. Even those which would benefit won't do so in normal daily use, only when using maximum throttle and load. Higher cetane doesn't provide a tangible benefit in diesels.

(Normal 95RON unleaded is actually "premium" unleaded, because the basic European standard unleaded is/was 91RON, which we never got here, but was briefly popular in the Teutonic countries and flatlands in the late 80s, early 90s)

Barkin

Mildly_Miffed said:

Unlike the more expensive petrols, there's zero functional difference with the more expensive diesels.

The only difference is in the brand-specific additive packages added at the cross-brand regional distribution depot to the base fuel - the base fuel is the same for all brands, because it's pipelined from the handful of national refineries.

I bet those who say they can tell the difference wouldn't do so in a double-blind trial.

I can't tell the difference when driving, but my old diesel definitely does less frequent DPF regen's if I fill up with Esso rather than from the Tesco next door.

shiraz99

Barkin said:

Mildly_Miffed said:

Unlike the more expensive petrols, there's zero functional difference with the more expensive diesels.

The only difference is in the brand-specific additive packages added at the cross-brand regional distribution depot to the base fuel - the base fuel is the same for all brands, because it's pipelined from the handful of national refineries.

I bet those who say they can tell the difference wouldn't do so in a double-blind trial.

I can't tell the difference when driving, but my old diesel definitely does less frequent DPF regen's if I fill up with Esso rather than from the Tesco next door.

I tend to agree, and for some reason I definitely can tell whenever I've used Morrisons diesel in the past, which I now avoid.

Barkin

shiraz99 said:

Just filled up today at Costco with their so-called "Premium Diesel" but is it really premium in the same way as, for example Shell's Vpower diesel, or is it just.marketing guff. I did have a good look at the pump but all I could see was that is B7 diesel, which afaik is just regular diesel.

Premium diesel is B7 too.