Can I varnish previously oiled wood?

try http://www.rehabbersclub.org/

i don't have time to check for you right now, but there are many articles there about dealing with old houses, and i know windows have been a hot topic. oil is best for the moving parts if they're double hung windows, and would more than likely prevent varnish from properly bodning. you'd probably have to do something to draw the oil out of the pores, but i'm no expert.

you might also find information at the old house journal website.

Don't get carried away with the silly answers. If the varnish is sound all you need do is to remove the shine. The easiest way is to use an abrasive nylon pad. Vileda and Scotchbrite are two brand names. All the major DIY stores will have them. Rub the varnish down with white spirit and the pad until the shine is more or less gone (wear rubber gloves). Wipe off the slurry with a cloth. Once you have done this there will be a 'key' for undercoat and a gloss or satin finishing coat. If you don't remove the shine the new paint will chip off constantly. Preparation is everything with painting.

Well I'm sure not a carpenter but here's what I would do, scrub the door down with "dawn" ( do U have that lq. dish washing soap there? ) it cuts grease really good, and would take the oil off, then if worried about mold and weather, paint it with marine paint ( the kind they use on boats) I did that to my cheap wood lawn furniture about 30 years ago and never did bring any of it in and it looks like new. Just pick a color you can live with for a long time as Marine paint is not cheap, or varnish = )good luck.

It depends on what kind of varnish you're using. Some you have to sprip the wood clean then use it others you just put on top.

Hope this helps

Consult a carpenter