Astra J auto Sri, 2010 plate, 50k miles. 

The coolant in the expansion tank has turned into what I can only describe as a thick chocolate milkshake. Currently arguing with a finance company as I haven’t had the car long. Assumed it was an oil cooler problem however two garages won’t touch it because it might not be an oil cooler issue, Vauxhall themselves have quoted six hours to flush and strip it all for a diagnosis but think it’s engine oil and not transmission oil and have said it might n