dudes. stop.
this is like the blind leading the blind

boot polish on interior. no.
boiled linseed oil on interior. no.
megs tyre gel on interior. no.
applying coats of these items on interior plastics will more than likely lead to streaking and uneven finish.
first off, just how bad is your interior? maybe some pics would be an idea so we can see how faded it is?
i'd start with giving it a bloody good clean with an APC (eg. meguiars APC) and then using a product like Poorboys Natural Look... much better for interiors as it leaves an even finish.
I have used many products on interiors... the one thing I have learnt is that the more high gloss you go the more dust you attract and the more uneven the finish with egdes and vents missed out etc... keep it natural and the finish looks a hell of a lot better.