Yes, you just need to scuff (but a good scuffing in the crevices too). Forget filling the grain on installed spindles - you'll shoot yourself in the head before you get finished the first one. The grain will be a visible texture in the paint but - in my opinion - it looks good.

I'd recommend using painters mitts rather than brushes.

You are always going to get a better bond with a primer if the surface is dull. I don't really know what scuff sanding is, but the goal should be to dull the sheen of whatever finish is on the spindles. Do not expect primer or paint of any kind to fill grain. Sure, it may fill the holes and pits of the deep grain, but you will still be able to see it unless you use a grain filler or brushing putty or fill it somehow by skimming over over it with a patching compound. They do make spindle rollers....I've never used one, but they look pretty handy. You probably just want to use it to get the paint on faster, and then backbrush.

Is it impossible to use some type of grain filler for spindles? I've read trying to do that on a vertical surface isn't easy. If so, what would be your recommendation?

No, it's not impossible. I would use the Brushing Putty or just patch with some lightweight joint compound like Sheetrocks Plus3. Prime before applying. The Brushing Putty has a small learning curve in that you can't put it on too heavy or you will be sanding forever. Plus, it is expensive and you may have to custom order it from somewhere if you can't find a retailer that deals with Fine Paints of Europe. Personally, I like the look of the grain showing through in oak so I would just paint them. You may want to apply a coat or two of paint to see how you like the look before going through the grain filling process. The only good thing here is that whatever you decide, it's only 10 spindles...at least it is not an entire winding staircase.

Come to think of it, why not just replace the spindles? If you are handy enough to pop that top railing off, you can easily yank the oak spindles and replace them with pre-primed poplar spindles or pine or whatever grain free wood they may be made of. You can even apply your finish coats to the spindles before installing them.

Paintguy - So you think I'd be better off with the Sheetrock Plus3? Is that something I could grab at Lowes or Home Depo? I don't know if I'll bother messing with the grain thing. Sounds like a paint. Would be interested for the curved middle section. I'll see after the paint like you suggested.

I have considered replacing the spindles. I don't know how to take the railing apart but I'm sure my Dad would helpe me. The stairs are only a year old though so I feel like it would be a real waste.

Since the wood isn't very old, there's no stains etc. would I be ok using another type of primer? How many coats of primer should you typically apply or does it vary from manufacturer?

I never apply more than one coat of primer. As long as you give it a full coat, you shouldn't need to. I always opt to apply multiple finish coats instead of multiple coats of primer because finish paint will fill more and cover better. The primer is just used to solve the initial adhesion issue.

The thing about railings is that sometimes they are bolted on with a lag bolt and other times it may just be two nails on each side. If it's nailed, it shouldn't be too bad to remove.

Yes, you can get Sheetrock Plus 3 at Home Depot. I like the stuff that is tinted yellow, but I believe you can only get that in 5 gallon boxes. Plus 3 is the one with the blue lid. You probably just want to smear it on over the grain with your finger and then when it's dry you can sand it smooth. The hardest part about this technique is that you do not want to push it into the deep grain....you want to sort of float the compound over the top of the grain so that when you sand, you end up with a flush surface. It's best to use a broken in sanding block to sand with as the stuff will sand really easily...it's really lightweight.

Thanks for the clarifications! You've been a lot of help. Now I just need a free weekend!