I had an issue with my shackles and vinyl bushings with a 2 year old trailer with less than 10k miles. I changed them with heavy duty greasable kit. I believe it was made by dexter. It had thicker shackle plates, bronze bushings, greasable bolts. no more issues:D
I had the same issue with my 08 also. I gave it a quick shot of shop air. and let it completely drain to get any crud out. although the syringe does sound that it would have been less of a mess.