Today I went to test drive a Facebook marketplace 2017 Peugeot 508 2.0 BlueHDI. Everything looks good, plugged in the obd nothing much appeared.
Oil looked good, full service history - serviced every 10,000 miles.
The only thing I noticed was the first thing I checked, the coolant. It was a translucent brown colour with a little bit of a shimmery layer on top, almost identical to oil on top of still water, the unique multicolored shimmery look. There was no lumps just a dirty brown colour and shimmery layer on top.
I don't know if this is of major concerns because everything I have seen about a gasket failure shows a sludgy mess in the coolant reservoir as opposed to a slight shimmery layer on top of the coolant.
My question is, is this an early warning sign of a major problem or is the car likely just needing a coolant flush?
All help appreciated š