2005 ZX5 2.0L Duratec w/5 speed manual transmission
Just changed the manual tranny fluid (first time-used Royal Purple Max-Gear full synthetic 75w-90) and replaced the spark plugs (first time-used Autolite XP Iridium).
Spark plugs made a noticeable difference in acceleration and tranny seems about the same. I didn't have any shifting problems, so I didn't expect a huge difference.
I bought this car new during the employee pricing deal back in 2005. I haven't had any problems with it and haven't done anything major except a new alternator last year.
Love this car!!