I read your weekly column religiously. Anyway, on my 2007 V6 Rav4 I have always manually shifted my automatic trans a lot. I downshift when going down or up hills or when I need to slow down quickly on freeways, and I usually shift into neutral while waiting at a traffic light. My buds tell me I’m needlessly wearing out my trans. I say I’m helping my engine and brakes. Who’s right? You can call me Gearbox Greg. Thanks!
Gearbox Greg, replacement brakes are a lot cheaper than replacement transmissions.
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Why ? The engine doesn’t really care ( I think it adds wear that way ) but as far as I am concerned it adds unnecessary wear to the transmission .
I also don’t think much of the neutral thing at stop lights, waiting for a long train yes .
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Yes, but how much excessive wear is it really causing to the trans?
I suggest you continue to manually shift your auto trans if that’s the way you prefer to drive. It isn’t going to hurt the transmission. Not as long as you avoid gear/speed combos that make loud and weird noises, like 1st gear/65 mph. By manually shifting you are just opening and closing valves in the transmission that routinely open and close as a matter of course as you drive anyway.
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downshifting to go down hills can improve safety – by reducing chance of brakes overheating
downshifting to go up hills seems unnecessary
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I am still offering, for $19.95, plus shipping and handling, my manual shift conversion kit. For a limited time only, I will toss in a second conversion kit. All you need to do is pay the shipping and handling on the second conversion kit.
I make these conversion kits from genuine supplies available at Walmart. I purchase gearshift knobs in the auto parts department and short handled plungers in the plumbing department. I use super glue to attach the shift knob to the plunger handle.
The conversion kit is easily installed. Simply coat the inside of the plunger with Vasoline and affix the assembly to the floorboard of your car. You can shift away at your heart’s content while your automatic transmission functions normally and you save wear and tear on your shift linkage.
Better hurry! This offer is only good for a limited time only!
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You’re doing nothing good for your car, except when you downshift on long hills. It’s adding a slight bit of wear to the tranny. But if you like it, and you’re not messing up traffic, have your fun.
Sort of defeats the purpose of having an automatic transmission.
The transmission will do that when needed automatically
Your brakes will slow you down far more quickly. It’s their intended purpose.
Unnecessary, and a safety issue on top of that. If you leave the transmission in drive, should it become necessary you can accelerate away more quickly than if you have to shift the transmission into drive and then accelerate.
Your reasons for doing what you do don’t hold water. Your buddies are more correct than you are.
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+1
I have been downshifting my automatic transmissions on long downgrades for as long as I’ve been driving (50+ years, in case anyone is interested…) and I have never experienced transmission problems on any of the cars that I owned during that period of time.
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Especially if we’re talking about a manumatic (where you click the shifter into a zone that’s meant for manual shifting) then you aren’t doing much, if any, harm to the transmission by shifting manually. The computer is still vetting your shifts, so you won’t for instance be allowed to downshift to 1st when doing 75mph. The minuscule extra wear you might be putting on the transmission means the transmission’s life may be shortened to the point where only 5 other things on the car break first and make you get a new one instead of 6. If you enjoy the pseudomanual shifting, by all means keep it up.
Keep up with transmission fluid changes, though. I’d be willing to bet at least one of those friends preaching about premature transmission wear hasn’t changed his fluid in the last 100,000 miles. 
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