I want to add some fluid additive (Lucas) to my transmission, but I don't want to overfill it. The dipstick has add, warm, and hot for measuring. So how hot is the hot level? My temperature gauge only gets up one third of the way going 70 on the freeway, and the fluid only gets up around the bottom of "HOT". Can I safely add more fluid in that range (less than a quart)?
Edit: For the record, this vehicle is a 2000 Dodge Neon. As jmort indicated, I filled everything up over time and the level didn't really go up too much (maybe 1/4 or so of the way up on the HOT portion of the dipstick -- the bottle was 24 oz).