I’ve taken to using Bisley gun oil as an alternative to 3 in 1. A finer grade of oil(?) and still comes in a proper tin. Available from Amazon (£3.60 for 125ml) if you can’t get it locally.
I’ve also quite a stack of larch offcuts from a workshop build and had wondered about using some as kindling. My only concern was that as larch is quite a resinous wood, is it wise to use it in a woodburner - increased risk of chimney fire?