Is it harmful to your car if you change fluids TOO often?
 

my mechanic suggests that people change their transmission fluid twice a year.
i know the suggested interval is about 60k miles. well atleast according to the owners manual.

so is it harmful for the car if ANY fluids are changed too often?
like engine oil, coolant fluid, tranny fluid, differential fluid

I mean these things have these set intervals for a reason... right?

Harmful to your wallet maybe. Only changing the break in oil (On certain new cars) is a bad idea to change it too early.

On another car forum I used to belong to, there was a guy who used to work for a major transmission repair company. They used to rebuild many of the Japanese and other car manufacturers transmissions. These are often the ones that dealerships use as replacements. Anyway, if I recall he used to change his trans oil every time he changed oil. Just a drain and fill, but that was about every 3-4K miles. Obviously he never had a transmission problem so while I think that might be over kill, it surely can't hurt.

Also just to add, On past cars that I have had the transmission fluid changed at the recommended interval, I noticed the transmission shifted much smoother than right before. That tells me the new fluid is better than the old fluid. If the old fluid were still good and doing a perfectly fine job, I shouldn't really notice any difference. So with that said, I used to try and get into the habit of changing the trans fluid twice as early as what the dealer recommended, but those were the days of 30K mile transmission fluid changes. I would probably just stick to once a year if you wanted peace of mind, but wouldn't really sweat it either way.

Its not harmful at all to change fluids often, but, with transmission oil it can sometimes be dangerous to do a full change if the fluid hasn't been changed for a long time. The chemicals in the new fluid can sometimes dissolve the sludge created by old fluid, and that can cause leaks/clogs.

twice a year? i change it every 3 oil changes and it starts to become black at that period.

I use the maintenance schedule as a guide. Nothing beats knowing your own driving habits and popping the hood and checking for yourself. I changed my oil last November and a few weeks ago when I checked it still looked good. I think it'll be harmful for your bank account since I consider it a waste of money.

get a tranny cooler if you are an aggresive driver... it's a waste of money and doesn't benefit the environment any if u change often. plus there is room for error when the correct amount of fluid is not added. Just a few dollars in investment will give u a piece of mind and also reduce waste.

highly recommended cheap mod.

as for oil... city driving, follow recommendation.
highway and constant consistant rpms... do an extend oil change interval.

check rock-a-lex post on tranny cooler and jeffstai post on larger oil filter.

+1 Won't do any harm, except to your wallet.

Sounds like your mechanic is on commission! Haha!

if you put in a tranny cooler should you add a little extra transmission oil or is it not that much of a difference to show on the fill line?

BTW, i started doing 2 quart incremental flushes on the transmission and my fluid stays nice and pink. I also changed out the Power
Steering fluid reservoir on my GS4 on a sunday...then on the next sunday did it one more time. I have to say that my PS feels smoother.
I even got a friend to drive my car before I had did this. He actually said he did feel the difference.

You sound like my brother
 

He swears he can feel his car running smoother after he changes the engine oil.

The mind is a funny thing.

The difference is 1-10% only.

What convinced me there is some benefit in changing the transmission oil earlier than the recommended schedule was when I took our previous RX330 in for maintenance at the dealer. The next day when my wife drove it she asked me of they did something to the transmission because the car shifted much smoother. She didn't know what I took the car in for and I didn't tell her. She was the one that mostly drove the RX, so it felt a lot smoother to her than before.

I know I could always feel a difference when I changed the trans fluid, but I knew the work was being done so it could have been in my mind. However, if someone can feel the difference immediately and not know anything about what was done I think that it valid.

^ I get that feeling too. That's why I change it often.

What he said.

I don't think it's harmful to change your fluids too much