Some 2009 Ford Crown Victoria, Mercury Grand Marquis and Lincoln Town Car models may leak fluid from the right rear axle oil seal.
According to Ford, the leakage issue could be due to either a defective oil seal or a rough surface finish at the seal area of the axle shaft that slowly wears the oil seal away. Fortunately, the car maker has some build dates that will tell you what vehicles are affected and how to deal with the problem. Here they are:
Cars built between July 21, 2008 and Oct. 24, 2008 have been identified as having the poorly machined right rear axle shaft. On these vehicles, replace both the axle shaft and oil seal with updated components, (Part #6W1Z-4234-A and 3U2Z-1S177-AA, respectively).
Cars built from Oct. 25, 2008 through Nov. 14, 2008 already have the improved axle shaft installed at the factory. On these vehicles, just replace the oil seal with the updated version. Note that cars built
after Nov. 14, 2008 come equipped with both the improved axle shaft and seal, and therefore shouldn't have any fluid leakage issues whatsoever.