I have had the Whining sound when putting my truck in reverse when its cold since I bought it, I know this is normal, Monday I noticed my tranny fluid was a bit low, so I added in about half a quart of ATF +4, this brought it back up to full, and also it Eliminated the reverse whine. I was quite happy.

I put some cardboard under the truck to check for leaks, Not one drop after sitting for 24 hours. I have had the truck sitting on the cardboard all week when parked....Still there are no drops.

3 days later I noticed the reverse whine is back, and my tranny fluid has dropped from full to about halfway between min and full.....What happened? How can I have a leak when there...is no leak?

Should I add some more ATF to bring it back up to full again?

And yes, I am checking it when its warm, and idling in Neutral.

 

Leave it in the middle.

 

It may be leaking out somewhere else, while you are driving down the road..... Keep in mind, from add, to full, is only a PINT of fluid, so, losing a half pint somewhere isn't that much of a stretch.

Aside from that, I agree with aim.

 

For whatever reason, the trans fluid dipstick is not as easy to read as the engine oil dipstick.

Sometimes what you think is full is just fluid clinging to the dipstick after you filled it.

I always look for the spot on the dipstick that has fluid all the way across the dipstick, not just some at an angle.

 

Thats also what im looking at.

It went from completely full after filling on Monday to down to halfway between full and min in like 3 days with no noticeable leaks...I don't get it.

When it was full my reverse whine was completely GONE.

My transmission pan is bone dry...no sign of leaks anywhere.