There is a slight difference between the Antique Oil and the Tung Oil Varnish. The Antique Oil has slightly more “varnish” in it and uses a faster evaporating solvent. Probably more like naphtha than mineral spirits.
That said, a reasonable facsimile can be made by mixing equal proportions of your favourite varnish or poly vanish, boiled linseed oil and mineral spirits or naphtha. If you want a faster build, use slightly more varnish. Nothing magic, just keep trying until you find a mixture you like.
– Howard Acheson