Q: stiff gear change

Hey there. One of the problems associated with buying a used car is having accurate data on how the previous owner maintained the vehicle. When you mentioned that after diagnostics were completed, that the technician discovered that dirty oil was the problem it seems pretty evident that routine service and maintenance may have been an issue with the previous owner. It definitely raised a red flag with me.

However, what typically doesn’t show up on a diagnostic check is what damage the dirty oil may have caused to the engine/transmission or other components inside including gaskets, o-rings, or gears. Oil works best when it has reached an operating temperature, which is most likely why you’re having problems shifting when the car is cold and why when you shift into reverse initially you hear that "BIG CLUNK"; and when the car heats up, it becomes smoother.

The one thing that dirty oil does a good job of however, is masking mechanical problems inside the engine and transmission case of a manual transmission. It’s quite possible that changing the oil simply brought to life the damage that had been done previously because of wear and tear and lack of proper maintenance. Having 126,000 miles on your manual transmission is about when you’re due for a transmission inspection.

Let us know if the problem smooths out over the next week or so. If not, a good road test and diagnostic check by a qualified mechanic can give you a good starting point for fixing your shifting issue. Thanks for writing into us today! I hope your problems go away sooner rather than later.