Thanks for the info on the grey cap guys - I always believed that the green cap was just a more reliable cap than the grey one. Never considered different pressures!
As I'll be replacing most of the cooling system anyway (including radiator and reservoir*) I'll probably fit a green cap. All my '96 and later 940s have had green caps, so its strange that this car has a grey one fitted - apparently at the factory, as it looks aged.
*I'll be replacing the reservoir as I want to do the low coolant warning light mod, plus the existing reservoir looks old and brittle. I usually replace the radiator when I buy a car and the original one is still present, to prevent the autobox being damaged by any internal radiator corrosion allowing coolant and transmission fluid to mix. I have a Nissens one on order - in fact the same trader is supplying the condenser.
Re getting stuck in straight away, I have the 850R as the daily driver, so I have the luxury of getting the 940 fully sorted before using it as the DD. I was hoping a weekend's work would do it, but now its looking like its going to take a while longer than that!
I usually allow £500-750 on top of the purchase price to do these repairs, but it might end up being a tad more than that this time. That doesn't worry me too much, its just the fact that I have all this work to do - I have long covid and a few issues resulting from that, so can't work as long or often as I used to. Buying the 940 was supposed to be therapeutic
