 I bought a 2007 Nissan.  I have 53,000 miles on it as I do alot of driving.  At about 46,000, I was on a long trip about 6 hours into my travel my RPM's began to fluctuate, power was lost could not go over 20mpg.  I pulled over on I-10 near lordsburg.  After 20 minutes car started up and made it to Ca.  I took car to dealership and was told nothing was wrong. Once again at 53,000 I was driving to Ca. again and once again about 6 hours later same thing happened.  This time tranny blew.  Fluid was all over. Towed to Tucson, covered under extended warranty.  Before this everything on car seem to work.  Does a tranny usually go out this quick? 