For those of you running GL5 in your NC 6 speeds, here is why you shouldn’t. GL5 isn’t rated for bronze/brass components and what happens is the phosphorus in the GL5 will ash up with contamination from the yellow metals. The ash builds up in this little windage seal that helps feed the fluid pump.
Yup, the NC 6 speeds have an oil pump in them. It’s a little plastic impeller that feeds oil through the main shaft and feeds oil to the gear journals. It can’t do that when the oiling system is filled with this stuff!
Please find a proper GL4 to use. We are working on our own fluid creation and are having great luck, but finding a manufacture for it is the hard part.
We like suggesting Ford’s synthetic manual transmission fluid for those not local to pick up some of our own blend.
