Use a 50/50 mix of valvoline synromesh and mobil1 synthetic, have also used the valvoline ATF in the red jugs

 

That’s what I was going to pick up is the Valvoline do you have a T5 Z and did you have those same problems and what you just said fix them

 

I have a T5Z in one car, and regular T5 in the others, no issues with grinding in any gears. My son's 94GT grinds a little if you shift into 3rd too fast when the car hasn't warmed up yet.

 

That means it's time to replace the 3rd gear synchro. Do it now before it ruins 3rd gear. It's exceptionally easy to rebuild a t5.

 

Cheap ass orileys Dextron 4. I've used Royal purple synchromax too. Never noticed any difference.

 

I rebuilt my T5 myself back around 2006 or so. I don’t believe the carbon fiber blocker rings were available then. Has the brass 5th gear synchro. Anyway, I filled it with Mobil 1 ATF.

it’s probably the best shifting T5 I’ve ever driven. Every gear plus 5th is smooth and clash-free. Not sure if it’s the fluid, or the fact I did a half-decent rebuild or what. It’s even silent.

The T45 in my ‘00 GT with the same fluid shifts like junk however, but it’s always been like this. So many it’s not the fluid.

 

Late, but I like B&M's "Trick Shift". Which is basically a modified Type F fluid. Tough to beat for smooth shifting. The extra friction modifiers in it help blocking rings "grab" just a bit more. It helps particularly if you are into speed shifting.