Whining noise after ATF flush

Hello everyone,

Has anyone ever experienced this??

I decided to drain my ATF last night on my 2000 Frontier 4-cylinder 2wd I picked up last week with 65k miles. I don't think the trans has ever been flushed, the fluid looked like it seen better days. (The previous owner claims that head it flushed at a local shop but had no records to show me). The fluid level was up to the hot mark on the dipstick but I can't remember if it was slightly over the mark now.

I measured the amount of ATF that came out, approx 4.5 qts. It was either my Chilton manual or the Nissan manual in the glove box saying to refill with DEXRON III ATF. Added 2 qts of synthetic ATF DEX III and the rest with regular ATF DEX III, that's all I had in my garage. Anyway after starting up I backed it out in to the street, level surface, and let the engine warm up, about 5 minutes into it there was a whining noise coming from the engine bay. I figured it was the trans since I just flushed it and the fluid level was low (I've had this happen before on other trans I flushed, it gurgles and whines until the fluid level is good). The Nissan manual says to shift into all gears and to drive the truck at least 5 minutes before checking the level.

Drove the truck around the block and everything seemed to be warmed up, put it in park and let it idle, then I checked the dipstick and sure enough it was low, added a little more fluid which almost equaled 4.5 qts. Brought the level back up to the highest "hot" point on the dipstick. The whining noise went away, checked the fluid level several more times to make sure and it was good. Everything seemed good so I shut the engine off. I noticed that I used slightly less (probably a few ounces) ATF then what I drained out but the dipstick showed that the fluid level was where it should be and I don't want to overfill the trans. I can't remember now that when I first checked the dipstick before the flush if it was a little over.

I let the truck sit for about 20 minutes and then decided to go grab dinner. A few minutes into my drive I noticed the whining sound returned. After driving a few miles I rechecked the dipstick and the fluid level did not change.

My question to all of you with a KA24DE engine and auto trans is...have you ever experienced this before after an ATF flush?

I have to assume this is trans related since it just started after the flush, unless this is a total coincidence and it's something else. I'm using Dexron III, do any of you use anything else??

I'm tempted to add more ATF, just enough to bring it back to the exact amount that I drained, but this might bring the level slightly over the hot mark on our dipstick...Is the level marks on our dipsticks off??

Please let me know what you have experienced? Thanks...