Gāday mate, Iāve had this same problem shared by many Fiesta owners & finally solved the problem. At 80k miles on my 2011 manual Fiesta S, my mechanic noticed transmission fluid weeping from right axle & replaced the seal with the stock metal ring seal. Within a few weeks weeping continued & he replaced it again with a new metal ring seal. I became frustrated & replaced it myself twice more after! Once with an all rubber seal from āNational,ā which leaked immediately the day after, then again with the metal ringed OEM CV6Z-1S1777-A. It leaked within weeks. With Both self installs, I used meticulous care using seal installer tool & ensured it was flush with tranny casing. After exhaustive research & utter determination to figure this out, I came across this YouTube video about ford fusion tech service bulletins
(@fordtechmakuloco is a genius in all things Ford!). Now Even though it makes NO mention at all of Fiestas, it piqued my curiosity & made sense. The leaking issue is not a seal problem, but an issue where the surface of the axle shaft makes contact with the seal. See red arrow in attached photo. Whether from metal shavings internally or the integrity of the metal surface itself, the axle surface over time becomes scratched up & knicked, thus degrading whatever seal is installed. The seal never stands a chance! So either the transaxle needs to be replaced, or continue using your current transaxle & install the ingenious āSKF sleeve repair kit,ā which is an ultra micro thin metal ring sleeve that fits snugly over your scratched up surface of shaft area, making said surface a new shiny slippery metal contact, like a new axle outta the box. EITHER method will solve your problem. I know this because I tried BOTH methods & they both solved the problem. Why both? Because initially installed the SKF sleeve & I was astonished that there were no leaks! I kept checking it periodically, & voila! Bone dry, no leaks whatsoever, 13,000 miles later! (driving 150 miles a day as a FT Ćber driver). Everything right with the world! So I thoughtā¦.Well, after that problem was solved, I started to have totally unrelated right axle issues due to a torn cv boot= dirt & grime must have entered the cv joint area, & clicking sounds & wear convinced me to replace the entire right axle, totally unrelated to our SKF sleeve, mind you. BUT I left the same stock seal in place from 13,000 miles ago, & I installed the brand new OEM motorcraft right transaxle, and still to this day, 30k miles later, bone dry, no leaks, & not to mention the ride comfort & peace of mind of a new transaxle! Iāll include the YouTube information, link & photo of which aspect of the transaxle Iām talking about as im not sure if red arrow I added shows up in photo as Iām having problems attaching it on this forum, posting from my iPhone. Look up āSKF sleeve repairā too, as it lists the specific size to fit your model. Why Ford makes no mention of Fiestas with this issue I donāt know. If you need more details, Iām happy to help & I can email you links & photosā¦just hit me up! Hope this helps!