I strongly like spraying mine with old engine oil its free works well too
Downside is it can drip for a while so best not park where a few oil spots might cause a problem.
Got one of these to feed down the inside of the chasis rails on the TJ. works wonders flushing out all of the build up of off roading crap http://www.amazon.co.uk/Karcher-Drain-Cleaning-Hose-attachment/dp/B005NZAHH8Then bought a garden sparyer like this http://www.amazon.co.uk/Litre-Action-Knapsack-Pressure-Sprayer/dp/B00CSM54JK/ref=sr_1_2?s=electronics&ie=UTF8&qid=1377885878&sr=1-2&keywords=garden+sprayerThe drain cleaner thingy is the bit of kit I mentioned in an earlier answer BrynSpayed de-watering oil (got plenty at work) inside the chasis, will repeat the excercise after cheapfest