(2000 Sunfire 2.2L auto )To better describe the noise. a ticking noise only occurs while the Drive gear(auto. trans.) and not neutral, park, 1,2 or 3.

I noticed that while the car is stationary but the drive gear engaged, the noise only happens if the engine is idling lower than 1000RPM. If you bring it up over 1000 its gone or not noticeable.

Its a distinctive noise thats stands out when you shift through all gears Its not that loud at all, couldn't hear it with the radio on low. Its hard to tell if the noise is coming from the engine or transmission from in or outside of the car because its so faint.

There is a low pitch humming when I Accelerate hard anyspeed that goes past 3000RPM. Not sure if this is normal but not sure to notice it till now. I did over fill my tranny with 4-6quarts and drive 290Km on the highway 2 months ago.

What could this noise i just noticed be, do i need to flush my ATF ASAP? What should I do? Don't want any future major tranny issues.

RECENT CAR HISTORY within last 4 months

Overfilled my tranmission fluid by 4 or 6 Liters or Quarts (maybe 6 Qt)
I don't know when the ATF was last changed from last owner. 77000KM on it at the time I needs to be changed if it wasn't anyways.
I drove 230 km after adding 2 Quarts( 2L). Added another 2 quarts/L of ATF and drove 200KM at slower speed 80-90KM/h. Noticed higher transmission/engine noise. At stationary. the shifting of gears was louder and sluggish.

Got it drained by Mr.lube, they didn't say anything bad about foamy aeration or the state of the oil other than they aren't able to tell if atf is bad or not.

its been 3000KM since then. Didn't flush out the old ATF yet but going to. Half of the ATF is new mix and the other is the bad stuff. I don't really have 180$ right for a machine ATF flush at Mr.lub. I know the method of flushing it myself but never done it before.

A tech shoved the engine forward to check for play and mentioned my motor mount rubber bushings need to be changed.

I knew that i Had wet transmission lines (front driver side) before i left 400KM Drive. I had a seperate problem happen which was misfire or just 9 year old spark plugs being the cause. This caused loss performance, noticeably going up hills. Which led me to think the transmission was leaking bad. Couldn't check since theres no tran. dipstick, it was -30 Cel outside. didn't notice a leak while parked for 10 mins. Wasn't sure, just panic and added ATF.