I often downshift my 5spd from 5th to 3rd on the freeway to slow down w/o the brakes. (Of course I don't do this when there's traffic approaching from behind, but that's rare in any case :-)). Does this hurt the tranny, or may I safely continue to do it?

 

It won't kill it, but like my daddy always told me "brake pads are cheaper than engines." Same goes for transmissions.

 

That was one of the reasons I specifically bought the 6-speed manual tranny -- for more consistent engine braking. (The torque converter in an automatic does not give the direct connection to the engine that you get with a manual, thus diminished engine braking. Although I have to say that the automatics in the Maxima are much better at engine braking than the junk-automatics offered by GM.) The other reason I really like a manual is for more control of the engine-transmission in all driving situations (such as staying in 3rd gear for faster freeway entry).

I have to agree with the earlier post by Jacksprat, but I would say it somewhat differently: "brake pads are cheaper than auto trannies." A manual transmission is much less likely to experience problems when used for engine braking. The heat generated in the Automatic Tranny (particularly with engine braking) can cause problems that will affect the life of that Tranny. Heat is much less of a problem in a manual Transmission.

I rarely downshift for engine braking on the freeway (Interstate). But living in the foothills of the Rocky Mountains, I use engine braking for descending hills. I have to drop about 1,200 feet in elevation whenever I leave home. I use third gear for most of the descent, and second on the steepest part. Whenever I'm driving in the mountains, I use the gear that provides the best vehicle control, both up-hill and down. My overall experience is that the gear that is best for climbing a hill is usually the best gear (for control) in descending that hill.