I’m running (inadvertently) an experiment; when I was decorating last I ran out of oil-based Satinwood and in error bought water-based to finish the job. The result is the architrave is painted in oil-based and the doors in water-based. It’s been 18 months and the oil-based is getting quite yellow whereas the water-based is still as white as the day I painted it.
Thing is, when I was actually painting I was cursing the water-based as I had to apply 2 coats to get the opacity,whereas the oil-based only needed 1 coat.
Note: the oil-based paint goes yellow where there is no/very low exposure to VU light as the linseed in it goes off (it’s no good trying to re-colour the white with a VU light once it’s gone yellow!)
I’m now doing our Hall, Stairs and Landing so mucho gloss-work, upon which I am intending to use water-based paint even though I will have to go over it a couple of times because I’m unlikely to need to re-do it in 2 years time!
EDIT: as jonba suggests, the paint I used that has yellowed is Dulux, and I read elsewhere in teh internets that Dulux have fixed the issue, however I’m still going to go water-based.