Current vehicle has a few years of tar and tree sap deposits stuck to it. Not neglected just a daily driver. Can I use wax and grease remover to clean the surfaces prior to waxing?Would that be too harsh? Should I just buy a clay bar?

I myself would use the clay bar. I love the way it leaves the finish so smooth. Anytime I wax my vehicle I use the clay bar first. It makes waxing so much easier and looks nicer when job is done.

This is how I would do it since this is probably the first time you have waxed this vehicle in a long time.

1. First wash vehicle with DAWN DISH SOAP (only use this when your going to clay bar your car because it strips all the wax from your paint and is gentle enough not to harm it).

2. Clay bar

3. Apply a good wax. Meguires is good. I prefer Zano but that is a brand not sold in stores. Mail order only.

pure water is best for tree sap

I will have to pick up a clay bar, next time I detail it, thanks for the info. Maybe it is not tree sap, whatever it is, it is stubborn! Tried washing off (dish soap) no luck tried to wax it off and it just turned into mess of wax and little smears of gooey funk. Most people do not even see them but if you wax your vehicle you know they are there.

The claybar will peel that deposit right off.
I also prefer Zaino.. once applied, bugs and other contaminants wipe right off.