Well I just did this--drained the gear oil out, ran mineral spirits in the trans for a bit, drained that, and then filled it with 85-140 non synthetic. The transmission still grinds when shifting into first. The only difference is it now grinds when shifting into reverse as well. It usually doesn't do it until I've been driving for a while. Sometimes it won't do it at all. At this point, I guess I'm looking at a blocker ring or an adjustment. Does that make sense?
