XSeries-forum

[quote="AwB"]

Some really informative comments here, particularly re upstream and distribution processes.

...also some hilarious BS flying around, but that's been covered!  :blink:

So, question for those in the know... the additive to raise cetane values that is added at source, is this proprietary to the distributors or is it standard similar to the base fuel?  In other words do Shell, BP, Esso etc add their own version of millers?
[/quote]

Not a fuel expert per se, but I'm pretty sure that each company has their own additives, especially Shell Nitro+ and BP Ultimate Diesel

Here's  my 2 cents (or 2 cents plus additive)

2011 30d 45000miles owned since new, tried all permutations:
supermarket  only, 31-32mg
supermarket with additive (every time 32-33mpg and then every 5th or 6th fill up 32mpg)
premium (dearer) both shell / BP variants, 33mpg and marginally sweeter running (subjective and probably mind tricks)
.......

Always fill tank when getting close to empty, so additive easy measure from 'millers' bottle side neck filler. Keep it double wrapped in plastic bag in boot (don't overspill as it will stink a bit)

Full tank is just over 500-550miles with regular mixed driving.  Do get 41mpg on long straight run from Edinburgh to Aviemore and did once get 45mpg on trip to France (55-60 all they way - almost missed the ferry, did have to put a wiggle on heading into Portsmouth  )

So its Supermarket for me with additive every 3-4K just to help flush carbon build ups etc.

End of the day ye pays yer money ye takes yer choice.