On my 1986 Ford Ranger 5-spd manual, as I slow down why does the gear shift sound like it is rattling and I can feel it in the stick?

What really is happening is the bushings in the transmission are wore. Yes new oil and Lucas will help for a while, but the time is coming when the tranny will a rebuild.

Good day. My neighbor had the same issue. Now what we did was drained as much of the gear oil we could and replaced it with fresh. We also added some Lucas gear oil conditioner. No more shimmy or shake. Even shifted smoother. Hope this helps. Have plenty of rags and please recycle used oil or grease.