If I drain all the oil and coolant from an engine, is it okay to remove/loosen the cylinder head bolts? I want to check if there's oil in the bolt holes, not letting me torque my cylinder head correctly. I won't be taking the head off, just the bolts so that I can check for oil and retorque them all again. Will oil/coolant still be able to get into the holes after draining them?

I could be wrong, by my recollection is that all BMW head bolts are one-time use stretch bolts. That being the case they can't be re-torqued later.

Yeah, you are only suppose to use the bolts once. How do you know you can not torque the head bolts correctly, I mean what is it doing that you think you aren't torquing correctly. Even after you drain the oil/coolant, there is still some oil around the lifters/valves/springs, but it just depends on where it is if it will drip into the holes.

ive heard that if you have a leaking head gasket (blown head gasket) you can try to retorque the bolts and there is a small chance you can fix the problem with the head.
i dont think it should hurt to use the same bolts again!!

Are you kidding me?! Don't use the same bolts again unless you want to do the head gasket job for a second time a few days later.

Never retorque these bolts. If something is wrong I would take the head off and make sure everything is OK and order new bolts. Are you sure you just aren't trying hard enough? Those last 90 degrees are pretty tough.

Once you loosen the bolts enough to move the head, you have bolt problems AND need to replace the head gasket.

Oil on the threads of bolts won't prevent you from torquing them properly. Many head bolt torque specs on various cars are given with oiled threads.

By all means, replace the bolts, they are a "torque to yield" bolt, once yielded you won't have the correct clamping force. Check the bolt holes for oil/coolant, vacuum out, roll up a rag & twist down there, or clean out with carb cleaner. Liquid in there can generate tremendous hydraulic force (enough to break the casting - ask me how I know). A light coat of oil on the threads is all that's needed.