99 SL1 Transmission sound

I've 99, SL1, 1.9L, Single cam Saturn. It was making sound in Park or Reverse.
As soon as I shift from P to D, the sound instantly goes away.
I changed its transmission oil + filter and poured one L of Transmission fix into Transmission unit and now it makes sound only when car get started in Hot
weather and is in Park. In cold weather, Transmission doesn't make any sound at Park.
Should I use more Transmission Fix ?
Is this any other problem ?
Any advice would be appreciated.

Thanks.