I just read this thread an hour ago and have already drained out the gear oil and replaced it with Synchromesh.
When I got my non-world class T5 it had gear oil in it. I drained it and put new 90 weight gear oil in which was thinner than what I drained out! I still couldn't get it in first gear unless I was TOTALLY stopped, second was almost as bad. Cold weather made it worse.
After changing to Synchromesh I drove it six or eight blocks and the difference is obvious. Shifts better and goes into first before I come to a complete stop!
Thank you Tiny_Jaime for asking the question, and thank you Lugnutz for a great answer!
