I've been using ATF in my NWC T5 since I swapped it in in 2006. Question I have now is whether anyone is using that B&M Trick Shift ATF or their Stick Shift manual trans fluid or some sort of Royal Purple fluid, or if there would possibly be an advantage to using either? Hopefully I'll be rebuilding the T5 over the winter (really wish I had kept the other trans with the junk case that leaked as I had just put new rebuild parts in it ), and I'd like nice shifts.

Also, anyone know the reason for a rather hard shift into 5th? Seems like 5th engages when the shifter is almost at max deflection (against the 5th gear stop in the slider plate), which makes quick shifting when passing difficult sometimes. I'm thinking my shift fork is bent, but the other T5 I had (one I have is from an 85 and the other was from an 84) seemed to have the same problem, and, as I remember, I checked the shift forks in that one for straightness as I rebuilt it, and the 5th fork was fine.

 

Bump... If nobody knows about the fluids, maybe someone knows about the hard/difficult 5th gear engagement?

 

I use straight 30w oil.

recc by lots, even a ex GM engineere who does the same.

atf is to thin...

 

Just an note: The shop manual for my non-WC calls for ATF.

JamesC

 

try some 30w Mav n get back to me about that 5th problem....
never a problem going into any gear at any speed for me, less im sloppy on the clutch.

 

No problem here with ATF. Frankly, the whole 'fluid business' for the T-5 is downright crazy as the following link will demonstrate, I think:

https://www.thirdgen.org/forums/tran...ything-we.html

JamesC

 

Yes, I know... I have the "one size fits all" T5 service manual I "purchased" on eBay that's good for ALL T5's. Within the same paragraph, it says that either 5W-30 or Dexron/Mercon can be used, and the trans should be filled with what it originally came with. However, IIRC (have to double check), I think even GM got confused, as my FSM says 5W-30 and the owner's manual says ATF (again, IIRC).

Question I still have is whether there may be an advantage going to the synthetic B&M fluid or stay with the ATF. And still what could potentially be causing the difficult 5th gear shift. No, I don't have the trans apart right now, so I couldn't tell if the blocking ring is shot or the fork bent...

 

GM doesn't get it right all the time, sure some can member when they told folks to run a .060 plug gap, then quickly took it back.

Sure the HEI can spark off a 60gap, but leaves little wear room.


ATF was a quick solution that was thin enough to get into the bearings,
but its to thin for gear to gear contact like that, there is little cushion,
and neither is ATF designed for that, its main purpose is hydrolic fluid.

a synethic version ain't gonna be any better.

 

ATF is also a friction modifier (the latest stuff especially, the old stuff, no).

Wasn't referring to synthetic ATF, either, but to the B&M Stick Shift fluid (as opposed to the Trick Shift for autos), or synthetic syncromesh fluid, or even Mobil 1. However, I've heard that engine oil tends to make shifts difficult, and, like I said, my 5th gear is tough enough a good portion of the time.

 

can I use 10W royal purple? and what is the general oil change interval on a t-5? auto trans flushes are recommended every 50,000...

 

My t5 had a label on the side that said dexron 2...I just put gear oil in it lol.

 

If you put gear oil in your 91 T5 you just ruined it or shortened its life significantly. Your T5 is definitely a 2nd design WC tranny and requires ATF. Gear oil will attack the adhesive that holds the friction material onto the syncro rings.

Drain it right away and put ATF back in it and maybe it will live.

 

Is there a true synthetic ATF that will work in place of the regular ATF?

 

Man, I thought this thread was dead and cremated...

Well, I got the trans apart a few months ago and found out that the hard 5th shift was caused by bad fork pads, which have been replaced (one was worn completely through to the fork itself and the other wasn't far behind). It's been fully rebuilt now.

Still debating on what to use for the fluid... Going to have to figure it out soon as the entire powertrain is going into the 88 within the next couple of weeks and I want as many fluids in as possible so I don't have to take things apart and do it again later (like I'm going to do with the rear axle tomorrow ). I'm leaning towards the B&M Stick Shift, unless someone says otherwise.

Usual fluid change interval on manuals, as was taught in class, is 36,000 miles.

 

I thought all ATF was synthetic....

 

I just put penzoil synchromesh in my t5. I will let ya know how it shifts in a wk or 2 when i got it running.... there was dexron atf in it before.

 

Synchros were long gone when I got the car almost a year ago. I've had the gear oil in almost 2 months now, the only difference is cold shifting grinds a bit.

 

Well OK the syncros are shot but you are causing more damage with gear oil than if you had ATF in it. The WC units also need use needle bearings between the gears and main shaft and gear oil is not thin enough to properly lubricate them.

 

If you really need thicker fluid get some lucas trans oil. It is a really thick ATF.