Hi Newt
The thing here is that the Colron Spirit Dye is, as far as I know, white spirit based which means that the solvent in the oil is likely to reactivate it and disturb it, usually ending up in a patchy effect.
It's also worth mentioning that (again as far as I know, things may have changed) these stains sometimes use fairly cheap dyestuffs which may not be very fade resistant/colour fast.
The water based sanding sealer would have been a good solutions except that you want to put oil over it and oil works best on unsealed wood.
I reckon your best bet would be to use a different type of stain; a water based one should be fine or a Spirit Stain which isn't based on white spirit, but modestly prevents me from naming any names.
As Philly suggests, some experimentation on scraps is always advisable.