Bicycle Mechanics - Fork Maintenance

I have a InSync 323 fork on my Trek 4300. I have well over 5000 miles on the bike. Lately the front fork spring makes a noise (squeak) when i hit big bumps. It sounds like the rebound spring is dry and needs lubed.

Are these things serviceable or not? I tried to drip some chain lube down inside of it and worked the fork up and down many times. It still makes a squeaky noise. I had oil running out the bottom of the fork so i know i used enough.

I don't want to spend a bunch of money on this bike. Any advice for how to shut it up? Thanks.

Information on how to do it is usually impossible to get. It's not really economical for lbs to service them and manufactures often provide no technical documentation.
The above applies only to low end forks, particularly those produced by companies that don't also produce high end forks.

If you want to service it you pretty much have to work out how it comes apart. Low end forks tend to be fairly simple. Often they just contain a couple of springs and no damper.

A quick search on google came up with this.

link (http://www.cyclingforums.com/t90493.html)

No oil. Just a spring in the cylinder on the left, and empty on the right. you can remove the cover under the adjuster, with a large adjustable wrench - carefully!

I was looking for info on this fork, too. I didn't find much. The link provided in the post above is to a thread on cyclingforums, which had this link to In-Sync: http://www.insyncsuspension.com/ This page is simply a redirector to http://www.spinner-usa.com/ I've put these addresses here so that future searchers of the Bikeforums might have an easier time.

I think it's probably a testament to the quality of these parts that doing a google search for either company name (InSync and Spinner Inc) that are on the fork decals, turns up ZERO info on the actual company. But if you search for the other "major" fork makers, you get hits on their websites...