Although Subaru's cars tend to stand the test of time better than most in their as-new price class, older transmissions often leave something to be desired in terms of reliability. Some reliability issues are more serious than others, and most have more to do with improper operation or maintenance than with any specific manufacturer defect.
In order to understand what constitutes a problem, it helps to know how Subaru transmissions are programmed to work. Subaru automatic transmissions have a very aggressive "power" mode that helps the car to perform better with acceleration. This "power" mode delays drive engagement, raises shift points and shift firmness, and often makes downshifts a jerky and uncomfortable affair. While disconcerting, such behavior is to be expected from any Subaru automatic transmission.
Subaru produced about 816 automatic-transmission-equipped Legacys, Bajas, Outbacks, Foresters and Imprezas between 2001 and 2003 with a defective parking pawl that can cause the transmission to slip out of park at random. Although no injuries had been reported at the time, the company issued a recall for the affected vehicles in November of 2002. Affected vehicles are likely to suffer failure while parked on steep grades without the parking gear applied. As this failure was the subject of a factory recall, affected vehicles may be repaired free of charge at any dealer.
All 2005 six-cylinder, Sportshift-equipped Outbacks have a loophole in the computer programming that allow the driver to over-ride the engine's rev limiter while shifting in manual mode. While not technically a "flaw," this characteristic of the Sportshift can cause inattentive drivers to over-rev the car for long periods of time, causing oil and engine overheating problems, and eventually destruction of the engine itself. You could have the computer reprogrammed, but the cheaper solution is to simply be aware of the problem.
Most Subaru manual transmissions use small synchronizers made of brass or bronze. While the excellent lubricity of these materials provide for slick and easy shifting, neither one of them wear as well as the steel synchronizers used in most transmissions. A transmission that refuses to stay in gear or is difficult to engage is symptomatic of failing synchros, and a light golden sheen in the transmission oil is a sure sign.
While Subaru's powertrain warranty is generally considered quite good, it does contain one rather irritating loophole. Many owners whose manual transmissions fail in the normal course of usage have found that Subaru routinely classifies pre-mature synchro wear as a sign of "abuse"; as per Subaru's warranty language, such "abuse" immediately nullifies the powertrain warranty.
