I put GL5 in my AX15. What to do?

[Runnin'OnEmpty]

Several years ago I had a conversation with a Coastal rep on this
very question. He stated that Coastal buffers the sulfur/phosphorus
anti-wear additives, so that yellow metal damage isn't a concern
anymore. He said it used to be, but not anymore in the modern
formulations...

 

[Matthew Currie]

Buffered or not, I don't think I'd put dino GL5 in, considering how many other options there are. On the two AX15's I've had, I've now tried almost everything: GL5 dino oil shifted badly, made noise, and when drained after only a few thousand miles it looked as if I'd been panning for gold. Synthetic GL5 (Valvoline) worked beautifully on my 95 for close to 150 thousand miles without being changed. On my 99 I filled up with dino "synchromesh" oil and it worked fine for over a hundred thousand miles, until I crunched up the reverse gear trying to get out of a city traffic jam with a failed clutch. I just recently put the old tranny from the 95 (with 263k miles on it) into my 99 (with 257k). Working at the last minute as usual for a road trip the next day, I found that it was low on oil and I had none on hand, so I threw in some plain old 10-40 motor oil. It runs quietly and shifts fine. The only thing I haven't thrown into one of these is Dexron, but I suspect it would not mind that either. But it gets indigestion with GL5.