dfwroadkill

Each of our cars shift differently from the factory. The MN6 is meant to be banged on and isn't the smoothest tranny ever built when you consider the smoothness as it slides into gear. Many folks have discussed this many times on the forum and elsewhere. All I can say is that since I added the RP Synchromax, my tranny shifted very noticably easier, much smoother. Others have reported the same. I have no connection to RP and I feel like AMSOIL or Redline Products would have performed equally as well.

If you are happy with the way your tranny shifts, do nothing... If you wished it were smoother, you might try one of these products.... it's cheap, won't hurt a thing and you just might find something you've been missing... I don't know what else to say...

and no, Chuck, I haven't tried it in the differential.. someone else?

C66 Racing

I have seen probably hundreds of posts over the last three years by people who shifted from OEM to AMSOIL ATF, Redline D4 ATF or Royal Purple Synchromax report smoother shifting. I myself shifted from OEM to Redline at 800 miles and I too felt the tranny shifted smoother. After I started racing, I shifted to AMSOIL products as I felt they were a better match for my use.

Sorry for the confusion above. Royal Purple's website does report that the Max ATF is a Dexron III fluid, which is what our car takes, but I dug up a product application guide on their website which does say that the Synchromax is their recommendation for the C5 tranny. So all of you with that in your tranny should be fine.

Someone above asked about using synthetic in the differential. The requirement for the C5/Z06 differential is for a synthetic 75w90. Diff takes 2 quarts. This is what I use and recommend for the C5/Z06:
AMSOIL Severe Gear Extreme Pressure Synthetic 75w90

Gonzo

Thanks for your opinion

Chuck Harmon

I have ordered RP for the engine, trans, and differential. I am looking forward to changing out the oil and feeling a difference. I am wondering if there will be a reduction in noise too.

I will post my results within the week. Thanks for all the great feedback.

Chuck

atz06

I replaced the original tranny fluid with Redline at 6K miles and I have 12K miles now. I noticed a big improvment right away. I wonder the RP Synchromax is any better than Redline or not.

houston-z06

I just purchased a 2000 Black FRC from a member on this site 6 weeks ago and as a preventive measure, especially after reading this thread, have just ordered RP for my MN6 also and will comment after changing out. Ordered the purple ice also, just changed engine oil at the local Chevy dealer. Waiting for 383 stroker due from MTI this August to start using RP for engine oil.

Chuck Harmon

I just changed out the motor, transmission, and differential with Royal Purple: 10-30, Synchromax, & Gear-Max. The trans and rear had the original lube. The car has about 64,000 miles.

I can tell you I could feel the difference in the transmission immediately. Shifting into first while stopped had more of a metal on metal feel compared to how it feels now. Now it feels more like the gears were greased before they were engaged. You sure can't tell much difference between feeling the old fluid and the new with your fingers, but in the trans you can. My shifts aren't faster, just noticeably smoother

Perhaps the best proof of it being better is that after about 50 miles and a couple dozen shifts into first while stopped, I did not have one time when it wouldn't just go into 1st. A few times it was a bit hard, but not enough that I needed to go to 2nd or 3rd. Prior to this, I would have had to start from 2nd at least a couple of times.

I'm sure Amsoil would also provide similar results, I've heard good things about it too. I am told that the bearings will get even smoother with the passage of time using the new oil; but even if not, I am quite satisfied now. It was worth the 3-hour hassle to change out the oil.

Chuck

Paul 68

Thanks Chuck for the information. Did you change the transmission fluid yourself? I hope to get mine done soon. I see you don't live to far from me, I live in Alameda, California. I had My Z for Three Months. Take it easy.

Just Enough

I changed mine (Z06) to Redline D4 ATF and felt that it became notchier, the D4 actually is thicker than your typical ATF, I then switched to Mobil 1 synthetic ATF and it the shifts are easier and more positive. I have not tried Royal Purple. To reduce changing hassel I use a long 1/2 inch inside diameter tube routed from the fill hole out the fender well to a funnel which I bungee to a small step ladder. After 3 1/2 quarts go in, I start looking to see when it starts weeping out and clamp off the hose.

forsvette

Chuck and Paul68,
I will have to jump on this soon myself. We should all try to get together sometime this summer and gawk at each others rides since we are so close. Chuck, since you seem to have had your ride the longest, where is a good place for a tune around here? I don't seem to have much issues but I bought my Z06 from Ohio and would like to maximize the 91 octane gas here. Thanks guys.
Mike

vms4evr

I just swapped over to the Synchromax last night. And lowered the car 2 turns for starters while I was under there.

The 1-2 and 2-3 shifts immediately feel smoother. As somone else noted, not faster, smoother. The shifter itself is still ratchet like which is fine. Getting down into 1st gear at a stop is not a problem. This week I'll try some hard shifts at 4Krpm or so since that is where I was having the most problems shifting. I only ran about 20 miles and could easily tell the difference in shifting.

Graham

Paul 68

Mike, There a place here in Hayward, called Precision Motive, they specialize in Corvettes, took my 92 Corvette there, there a good shop. I will take my Z06 there, if i ever need work. Here the address and number. PRECISION MOTIVE 25417 MISSION BLVD, HAYWARD, CA 94544, (510) 886-0789. Paul

forsvette

Thanks Paul, I will check them out when I get a chance.

givemeurc6

Just put RP synchromax in my z06. I believe it does shift smoother but it's hard to tell. I have a brand new Hurst so it's still breaking which could be causing it not to be a 100% smooth. The car has about 12k on it and i believe the tranny fluid was never changed. So far so good. Now just to get my hurst broken in and it will be all good. Maybe time to put the softer springs but i hate taking my dash apart.

Paul 68

Does the synthetic Transmission fluid, make less wear on parts then regualar Transmisson Fluid? I want to put Royal Purple Synchromax , in my Z06 Transmission. The Mechanic, said if the fluid doesn't agree when the Z06 tranny, he can't warranty it, if something goes wrong. I just wanted to ask, if anyone has had any trouble with ROYAL PURPLE SYNCHROMAX if they put that in there Z06 Transmission. Thanks.

C66 Racing

The AMSOIL ATF does meet GM DEXRON III specifications and will not invalidate your warranty. This is the oil I use on the track and I can attest to its performance.

AMSOIL ATF

Request a Free AMSOIL Catalog
AMSOIL Ordering Information
AMSOIL Preferred Customer Program

IGO200

Regular viewers may remember that I've put up several posts regarding hard shifting.
Here's a brief synopsis.
'04 2500 miles, I didn't like the feel of the stock shifting, and I suspected a dragging clutch. Had to FORCE the dealership to bleed the clutch and there was a big improvement but I still was not happy with it. It felt "notchy" so I changed to Synthetic Mobile 1. Slight improvement in smoothness but as you all know, shifting really fast was out of the question, So.... I installed a Hurst. I loved the precision feel of the Hurst but would nearly break my wrist when trying to slam third.
I went to the dealer with a hard shifting complaint. They, of course blamed the Hurst. So I let them out the stocker back on and they proclaimed it acceptable. I said that I still felt it was NOT acceptable. To their credit, they offered to disassemble the gearbox for me, which they did- and spread the whole deal out on the table. I have a fair amount of transmission experience so I knew what to look for. I've got to admit I really didn't see much but they replaced a couple of speed rings and a fork that looked a little suspect. I picked the car up with the stock shifter and basic ATF. It was better but still not smooth.
Enter the RP Synchromax, which I put in three days ago.
This was a transformation. My transmission was SMOOTH and I was, for the first time since I bought the car satisfied.
Today I put the Hurst back on, and now - THIS is what I wanted. Now, I still can't powershift and I don't think the gearbox/engine/clutch combination will ever allow that, but as long as I lift even a little I can snap shifts nearly as well as I could on my old Hurst equipped '65 327/365, which is pretty fast.
The Royal Purple is THE ****.

Qksilver

I installed the RP synchromax last week and I think it's smoother, but it's hard to tell. During powershifts it felt the same, but for my everyday driving it's a slight improvement.

Chuck Harmon

IGO200,

I can't believe that with the trans out you didn't change the flywheel while everything was apart and opened up. A light flywheel would have given you the fast shifting you are looking for.

Dropping the rear suspension, the exhaust, the gear box, the rear end, the torque tube. All just to get to any part of the drive train. I never thought I would look back on the miserable 6 hour job changing the clutch on my '69 350/350 and think "those were the good old days".

Chuck

IGO200

Oh, I hear ya. But it was a warranty job and the dealer was already a bit tired of my face. Besides, I like to do one change at a time to when I'm trying to sort something out. In good time..... Headers next. I have LG LT's in the garage. I was waiting to get this deal sorted out first.