I am going to dry brush my sherman with oils to try and give the finish a more metalic look, and to help blend some things. Anyway, I would like to put the decals on after this and move onto weathering from there. My question is will the decals work O.K. if I place them on after dry brushing with oils?

I'm not sure since I've only worked with oils once, but I would think it would hamper decal adhesion (one of the reasons you are told to not handle decals with your fingers is oils). I would suggest spraying the area with Future or some other gloss coat, laying the decals down and then overcoating with a dull coat.

Andrew, I agree with Rob - DO NOT apply your decals after working your model with oils. Lay them down, and seal with a gloss or dull cote to protect them, before weathering with oils.

Note, that if you're going to weather (wash) with oils, you should gloss the model - not dull it. The dull cote is grainy, and your oil wash will spread out and try to fill the voids in the grainy dull cote. Gloss coting is better for this wash technique, as the smooth surface promotes the wash to flow where you want it.

Gunnie

+1 on what Sarahjoe says.

You should put the decals down on a glossy surface anyways.

After your oil dry brushing has been allowed to dry (at least overnight), give the areas where your decals are to go a spray with the gloss you normally use (I also use Future). Allow that to dry thoroughly, apply your decals, allow them to dry, and then seal them with another clear gloss over coat (which will also help blend the edges of the film into the overall finish).

After this second clear coat has dried, proceed with your normal weathering processes, whatever those might be. (I start with Dull Coat for an overall even flat finish, but that's me.)

The oils will have no adverse effect assuming that you allow them to dry completely. Once dry, they incorporate into the finish process about the same as enamels.

Depending on how much oil paint you use and the colors, it may take more than a day for them to dry out. However, my experience is that overnight is usually good for dry brushed areas. When in doubt, give it another 24 hours to dry. Titanium white, even when mixed with some enamels or other oil colors, seems to take the longest to dry.

HTH

Not directly on the oils,seal them 1st with an gloss overcoat, after oils are dried,then decals an be applied on the overcoat.