Can someone recommend me a battery for a 2012 monte carlo  diesel  cheers 

I have always used the Yuasa 5000 series 5 year warranty the last one we bought was the YBX5096 80ah and the car was part exchanged 4 years ago but the person who bought the car from dealers still has the battery fittedsio it's a least 7 years old, they run about £115 now but try the sites you might get a deal expensive battery but worth it as it lasts

Varta, Yuasa, Bosch (made by Varta), Duracell, Endoroline.

 

If you are changing the battery type (standard / EFB / AGM) or significant change to Ah you will need to 'code' the battery in, start-stop cars need EFB or AGM batteries.  

 

https://www.tayna.co.uk/car-batteries/types/096/tech/