I have a 90 accord lx and it shifts harshly and I've read to lubeguard conditioner in the trans fluid and it will help that but how much do I put in? Can this hurt my car?

I also have this big problem that I can't figure out for the life of me...

When it is cold outside and I get in my car drive down the street then go to turn my car off when I put the car in park the red light doesn't light up on the dash and it wont let me take my keys out until that red light is on. So I have to sit there for a few minutes and let my car warm up more and it comes on. If I drive for more than 20 minutes it usually comes on once I put it in park but not always. This is very weird because it only happens when it is cold not in the summer. Does anyone know how I could fix this or what is wrong with it?

Thank you

 

welcome to the forum, before you add anything to the trans, check your transmission control unit.

 

I had a friend who had similar trouble, turns out he had a tranny fluid leak. Make sure you check all the connections first.