Okay I recently did a search on this and it seems like I cannot find a answer to this. I wanted to run royal purple atf sythentic fluid in my t56 next summer but I been reading it could cause the blocker rings to fail. But others say they been running it years with no problems. It calls for the same stuff except it's sythentic. Would I be okay running this in my 94 z28. I put under 5k on the car every year. It's mostly a weekend cruiser. But I would rather run sythentic if I had the choice - Mike

 

i have been running royal purple for three years with no problems

 

Did you notice smoother shifting by anychance??

 

The T56 service manual says "Do not mix different brands or types of transmission lubricant. DO NOT USE GEAR OIL IN THE T56 TRANSMISSION SINCE THIS MAY DAMAGE THE BLOCKING RING MATERIAL." Synthetic is fine. I've been using Mobil Synthetic ATF for about 3000 miles with no problems.

 

Okay cool. From all the past threads I been reading on this site and the
ls1tech site. It seems a ton of people are running this in there t56 and had no problems to the few people that did have problems using synthetic atf. But they could have also maybee added gear oil or used the wrong fluid. I heard the blocker rings in the t56 transmissions were paper and the newer models had carbon fiber rings??

 

if you've had it rebuilt it will be carbon fiber, stock no.

 

I've also been running RP SYN in my T56 Rebuilt T56 for about 2 years now.. T56 Rebuilds actually recommends it and they know their 6 speeds!!!

 

In our 98 SS I went with Mobil 1 synth. atf and it took 2 weeks for second gear to start grinding on quick shifts so I put the dino fluid back in.
AFAIK the pre 98ish trans didn't have paper blockers and any rebuild gets them changed. So those cars should be fine with synth.
But I wouldn't recommend using synth on a stock 98 and up just because I'd hate to see it be the cause for trans work to be done.

 

I don't know what blockers pre-98s have but I've had Mobil 1 ATF in my 95 for about 15,000 miles with no problems and NO perceived change. The biggest transmission improvement I had was the Hurst Shifter ... after that there were no more of those "impressive" 2 --> 5 shifts! :-)