Royal Purple Tranny/Diff Fluid Swap
 

After passing 2K miles, I finalyl got around to changing out my stock tranny and diff fluid over to Royal Purple synthetic, man what a difference. First and foremost, the 1st to 2nd shift is so much smoother, as is the 2nd to 3rd, in fact those gears shift like shifting from 3rd to 4th, no jolting, not nearly as notchy, just very fluid.

the vibration in the shifter is also somewhat less, which is nice. Still feel some vibration at idle, but also not as bad as before. It will be interesting to see over the next few days have it feels as it breaks in. Little early to tell if it will help gas mileage, but this is a must for all you guys. Why don't they put this stuff in stock??? :D

so you've used a heavier weight then??

they don't put it in stock because mineral more than suffices, and it's a cost issue (like everything else). i know that was rhetorical, i like being annoying sometimes :p

I recently saw an episode of "Horsepower TV" where they swapped the differential, transmission & engine oil with Royal Purple and they wound up getting another 8 hp from their Camaro SS. Stated that it really opened up their engine and made it quite a bit more efficient.

A DIY or did you take it to a shop? What shop? :D

Just more reason to make me go out and buy stuff for the 8!
This also helps justify the spending..

I had MazMax do it for me, it was $120 total for fluid and work. You need about 6qt's of the stuff, which isn't cheap, so if you DIY plan on spending about $66 for the material. But it is so worth it. Best thing I have done to the car.

Neat. I'll be needing new differential fluid whenever I get some FI. Thanks for the tip brillo. :)

6 quarts? really? The capacity specified in the workshop manual is 1.4 qt. for the diff, and 1.85 qt. for the tranny. I'm purpling my diff tomorrow and red lining my tranny in 2 weeks. I figured 2 quarts each ought to do it. Also, another forum member PM'ed me that he used a total of four. Did MazMax maybe use 2 quarts to "flushed" the tranny and diff?

Also wanted to ask you: did you use MaxGear 75W-90 for both tranny and diff?

Tomorrow I'm going to "redline" my MT and diff.
Should be fun, I'll post pics on the site somewhere.....

When I had mine done they only used 2 qts. of each. I have read that there is no need to flush so I did not ask them to.

I did my own with redline, and it only takes 2 quarts of tranny oil and 2 quarts of diff oil.

Yes I used 75W-90 for both, its hard to find a straight synthetic 90 and both RP and MazMax said it was fine. The spec's for the capacities are not including some other reservoir, I'd have to ask MazMax where the other fluid goes. Brian at MazMax is a member of our Houston RX club, so he's a good guy and I know he knows what he's doing since he has 2-3? rotors currently....so I trust him.

Yeah, there is also a TSB from MNAO stating that due to lack of availability, 80W-90 or 75W-90 are also acceptable for the diff.

Synchromax in the tranny, Max gear in the diff. Check the sig: Royal Purple RULES!!! :D

Tony Orlando, why did you go with the Synchromax? From reading the RP site, it appeared to me that MaxGear 75W90 should be used in both tranny and diff.

jds

4 u :
https://www.rx8club.com/showpost.php...6&postcount=13
rx8cited

I had the max gear all the way around, as its the only one that meets the specs for both.

so im about to get some royal purple. let me get this straight, i wanna make sure before i put this stuff in, sorry.

differential - MaxGear 75W90
gearbox - Synchromax

this is for manual. thanks a lot.

I'm with who on this...spell it out for me I'm slow sometimes.

whosyourbaba, I'm not sure if Synchromax is a good idea for the transmission. Maybe RP specifically told tony it was fine, but the product description states it is primarily for manual trannies that takes ATF. The MaxGear would be the most appropriate for both the diff AND the tranny.

i was just trying to follow what others were saying, thanks for the advice. i found a local shop that carries redline, so im going redline since im positive on what to get.

Good choice. I ordered Red Line MT-90 for my transmission. I wasn't convinced that the combined GL-4/GL-5 rating of the RP would result in the best shifting action. It'll do just fine in the differential, though.

https://www.rx8club.com/series-i-tech-garage-22/changing-fluids-%3Deasy-fun-37600/

That tells me not to put Synchromax in the diff, but not the other way 'round.

jds

Question: What do I need to swap the transmission and diff fluids, other than the four (six?) bottles of RP? I saw some "crush washers" on Rosenthal mazda's site, is that the same thing or is that for motor oil? And is there anything else I need?

I was hoping to get this + clear corners + strakes all in one order to save on shipping.






PS: Do not leave the bottles of RP gear lube in your trunk. They will leak, and your interior will give off a subtle petroleum funk every time you get in. :(

There's lots of good information in the DIY: Transmission and Differential fluid replacement thread.

rx8cited

See the thread rx8cited gave, but here is a concise list of what you need for diff and tranny refill:

• 4 bottles RP
• 2 lengths of 1/2" clear tubing (5-6 ft.)
• Utility knife, for trimming tubing as needed
• 2x small plastic funnel
• ratchet
• short ratchet extension
• 23mm socket
• 24mm socket
• oil catch pan
• rags, lots of rags
• 2x Crush washers 9956-41-800 (diff)
• 2x Crush washers 2Y601-17-361 (trans)

That is it. Of course, a torque wrench is ideal, but you could probably get by without one. It is only 29-39.7 ft lb. for both drain and fill plugs. With the wrench I was using, I think 40 was the lowest setting. So, you don't have to seriously muscle it.

or a little pump, similar to a big shampoo or soap bottle. Super cheap and very easy !



https://www.rx8club.com/showthread.php?t=37600

I used a pump once with my RX-7. It seemed like the pumping to oil movement ratio was like 8,000:1. A whole lotta work...It was probably just a crappy pump, but in any case I found the hose/tubing and funnel to be super easy with no arm workout involved. Some other folks swear by the pumps, though. Different strokes for different folks (pun intended). :D

LOL, good one.

It took me about 15-20 strokes for the diff, and a bit more for the trans. Not bad at all

Limited Sip Differentials and Synthetics
 

Maybe my info is out of date, but a few years ago when putting synthetic in my diff I learned that if you have a clutch type limited slip it was important to use a synthetic designed for limited slip differentials—I believe the term used was “friction modifier.”

Anyway, the concern was the synthetic was so slippery that it would reduce the effectiveness of the limited slip diff by causing too much slip in the clutch packs which need some friction for them to work correctly.

I don’t know what type of limited slip the 8 has or if this info is even relevant with synthetics anymore, but I thought I would throw it out there just in case.

Holy bat crap that is hard on the eyes!

You have the same part number for both differentail crush washers. The 45 minutes brillo and i spent talking with the mazda parts dept came up with a different answer. Mind you I have not done the work as the crush washers are being ordered.

Part numbers I got where...

2 y601-17-361 for tran
1 9956-21-800 for diff
1 9956-41-400 for diff

I looked into this previously: https://www.rx8club.com/showpost.php...&postcount=285

rx8cited

I followed David at RP's advice and put in Maxgear on both and what a diference. Tranny is much quieter and feels a lot nicer.

Ah, that's exactly the data I was looking for. Thanks.

That is interesting. I forgot to compare the old ones before I tossed them (was paying by the hour to use the lift). Has anyone else successfully used the same part# for differential washers? So far, after 2 days of flogging I have aboslutely no leaks whatsoever.

When I asked the dealer months ago, I was given the same part # for the differential crush washers. That's what I used (details in the DIY). It's been 7k+ miles now, no problems.

rx8cited