'03 SE 42,000 miles.

It's 37 degrees out and wet. When I go over speed bumps today I hear squeaking from what sounds like the rear suspension. I'm sure it's bushing, but I'm curious as to the best method of lubricating and the best lubricant.

 

Crawl under with a bag of wrenches and start tightening everything up. Chance are it will be the rear shock bushings and at your mileage the shocks are warn out anyway. To cofirm what is squeakings spray some silicone or WD40 on a couple of bushings at a time and go drive to see if the noise is gone.
Mike