What's the best to cure a synchro ring problem that's been there since my
rebuild last year?

Ron at Ron's Transaxles, the SF Bay Area guru of these things, swears that
the Redline in my rebuilt 4 speed is causing a scratch from 1st to 2nd, esp.
when cold. He tells me to change the Redline to dino GL-4. Problem is, GL-4
is hard to get. The Royal Purple site says their GL-5 won't damage synchro
rings, and there are plenty who swear by Redline. I know this has been a
subject of discussion in the past and have searched the archives, even
finding another reference to Ron in 2003 who was then giving thumbs up to
GL-5. But now Ron has changed brands of syncro rings and that, he tells me,
is causing the problem with Redline.  An August 2003 post from Daryl gives
the ok to Redline.  Dennis, Oct 2002, says Mobil 1.

Main choices seem to be Sta Lube GL-4 and Redline. But Royal Purple is
supposed to be good stuff for engines...

Anyway this scratching from 1st to 2nd is driving me nuts. Ideas?