I own a 2004 forester 5 speed manual transmission w/approx 72,000 miles on it...it has started 'bucking' when in 2nd and 3rd gear....doesn't always do it, but does it enough to bother me...took it in for annual inspection and asked mechanic about it.he asked if i had the transmission flushed and said they would charge $79.99 to flush the transmission and add new fluid....when checking the manual it states that the transmission on a 5 speed uses transmission oil, and says nothing about flushing it out...am I being scammed? any info is greatly appreciated....