First thing I'd do is get the fickin adblue coded out, it's a pain when the temperature drops.
not had a problem with my ML Bluetec ..... (he says touching wood 
)
No issues with the pigs piss in hers either, once I can actually get some delivered from the usual ebay arseholes.
My Adblue has generally come from Costco
Newer cars will tell you how much is in the tank but mine will apparently just tell you when you're at the 500 miles to go .... I just put a container full in every now & then but have never had the warning
Costco are way too expensive, it was something like £10 by the time VAT went on for 5l. Even ShitFix/Toolstation is only £16 for 10l.
Her car doesn't even give a countdown, it says it's low, then you have a predetermined, but unspecified, number of starts before it refuses to start. The next model year did have a countdown, and tells you via the app as well.
Also, the size of the tank is compromised on her very specific trim model to get weight down, to get it in the £0 VED category, so the bloody think holds a max of 9l. So we chuck 5l in at a time, and just get used to doing it every 2 or 3 months depending on miileage/journey style.
We also keep the Ad blue in the utiiity room, as it doesn't like being stored incorrectly. Hence I wouldn't use from a petrol station shop where its left outside to freeze, and often in direct sunlight.
