[metroschultz]

The pins may be hanging up inside the cylinder, most spray lubes are O.K. I use WD40 myself, they sell a small one now with the tiny tube permanently attached. (which is good, cause the push in ones always shoot out on me), That said.
Spray or powdered graphite is also good. You just need to free up the pins and keep them smooth.
Put some lube on your key first and run it in & out 2 or 3 times. Repeat this process until everything inside feels smooth. Keep a rag handy, if you need to repeat more than a couple times, lube is going to drip from the cylinder. Then let it drain and in a week put in the graphite.
Hope it comes out good for you.
The alternate method is to drive to a locksmith who does auto work. They will usually R&R the cylinder, clean it and replace any worn parts for a very small fee. The guy near my house charges me $25.00 for the service.I use him a lot cause I sell so many cars.(I'm behind this year).
Schultz.