Not sure how or why I had been running Sta-Lube GL-4 for the past several years ago, but I switched to Sta- Lube GL-5 this year and have a noticeable change.

Old gearbox and I have no idea of the state of repair, but a GL-5 change is a big

In what way has it been better?

GL4 is for manual transmissions that DO NOT have a differential in them.
GL4 does not have "extreme pressure" additives.

In a modern transmission the EP additives can coat the synchronizers and make them not work properly.

The differential NEEDS the EP stuff bigtime...

I wouldn't have thought you could feel the difference between the two.

I also would expect early diff failure without it. It's the hypoid gears that need it, not the bearings.

The early synchronizes seem to be less picky than the late ones.

Most of the late ones have 2 or 3 different brass pieces versus the original single synchronizers.

Late seem better IMO but don't work well with GL5.

Probably the most improvement is finding 1st gear when stopped. I generally leave the trans in neutral at a stop light and engage 1st gear when the light turns. Also, finding third is often tight, but seems easier after changing to GL-5

On a safety point, and perhaps to avoid the grind, I always down shift (with the clutch in) coming to a stop. I have had too many situations where I have needed to get the hell out of the way real quick when at a stop to be sitting in neutral.

So when you drained the GL-4, did you find any metal in it?

Based on the recommendation of CMS, who did the rebuild of my transaxle, I used Swepco 201. I figure they know what they are talking about.

Is that stuff blue in color? If so, I use the same stuff.

Confusing answers as OP is using the right oil as per Dr Evils recommendation ,not prepared to question what he says ....this guy has seen it all and is the best in the business ,cheers.

It seems as though the synchro's like the GL-5, it slides into gear easier. Every so often getting 1st is a bit tricky, but I sense it's a linkage thing