Some marine stores have a neat little hand pump that screws into a qt-sized bottle and makes the fill part of the job much easier. Unfortunately, since the Redline bottles are not "standard", you will have to pour the oil into a regular oil bottle in order to use the pump. I tried several methods and the hand pump worked best.

so let me get this straight (haha sorry newb at this stuff)
i need 4 crush washers... 2 for diff and 2 for tranny
need 2 bottles of redline 75w90
and 2 bottles of redline mt-90

is this it? then i'm ready?

While you're at the marine store, get some 1/2 clear tubing. Fits the flotool valves that you buy at the auto parts store perfectly and fits the fill holes on the trans and diff perfectly. Flotool does not fit redline bottles. I transferred materials into clean 2 liter soda bottles.

I wrote up my findings in post #27 above.

Just finished doing this myself... It sure was nice to have all the advice in this thread!

A few notes:

1. I used the inclined driveway / Rhino ramp idea posted by msrecant in #19 above - my garage floor is apparently too smooth and the ramps just kept scooting forward every time I tried to drive up them (anyone else had this problem?). On the rough surface of the driveway they worked OK.

2. I used a little laser light level to position the ramps properly. Just put the level on the garage floor and shoot the beam out to the ramps to position them. Once you have the car up, you can double-check yourself by shining the beam along the tires. Using this method I got the car level on the first try.

It seems that the jury is a little mixed on whether there are tangible benefits to using the Redline... My experience is shifting into first is *definitely* easier as I'm coming to a stop, shifting in general seems a bit smoother (most noticeable from 1 to 2), and also, tranny noise in neutral (clutch out) while sitting in the garage is definitely less... It was such a striking difference, it made me wonder whether the factory had put enough lube in there in the first place, and it was just that it was filled properly now!

Anyway, I'm glad I did it. Thanks to all who've contributed in this thread and others on this subject...

Has anyone here tried using Redline's Superlight Shockproof fluid for the differential? I run this in my 2nd gen rx7, curious as if anyone has tried it in their rx8 yet.

Just wanted to express my gratitude for this DIY. My 8 has now been introduced to the fine family of RedLine gear oils. :)

Replaced mine with the recommended Red Line fluids recently at 11,000 miles. I used the plastic-tubing method; you can pick up a good length of 1/2" inner-diameter - 5/8" outer-diameter plastic tubing at Home Depot. This will just fit into the filler openings. To make sure there was a way for air to escape, I took a thick piece of copper wire and inserted it alongside the tubing to create an air gap. I bent a nice big loop in the other end of the wire to make absolutely certain that there was no way it could slip into the tranny case!

Attached to the other end of the tube was simply a kitchen funnel. There's room in the engine bay for the funnel and to run the tube down to the tranny. For the diff, I taped the funnel to a small ladder next to the car. The oils flowed well enough; if a bit slow. I figured that's not a bad thing because it allows the case to completely fill and not drip prematurely. Very easy; very little mess. A little diff oil did dribble on the exhaust and I could smell it for about a week.

Any difference? Yes. Not earthshaking, but positive. There was a noticeable reduction in gear noise right from the start. Shifting is slightly smoother, but it's a subtle difference. Neutral to 1st maybe a little notchier... but that goes away if you slow down the shift just a touch. In fact, slowing down all shifts just a bit seems to help realize the benefit of the new lube. Maybe that's why it felt like it took about 200 miles for the shifting improvement to become apparent; I was re-learning to shift for the way this lube works. I've also noticed that the occasional failure to properly get into Reverse hasn't yet happened since I swapped the fluids.

I changed mine to Royal Purple this weekend. I have 9,000 miles on my 8. I noticed a big improvement in the smoothness of shifting. I also think I have more power at the weels. This was easy to do. Used a 24mm socket for all of the plugs. On the rear differential I had to us a 6"" extension to get to the fill plug. I just used some clear tubbing and pushed it on the bottles and held it up in the air like a nurse would do with an IV. I cut a slit in the bottom of the bottle to let air in.

Trans and Diff System Flush
 

I didn't see this mentioned in this thread so here goes ... When we change our engine oil, we're only replacing 3.75-4.5 qts of the oil in a system that contains approx. 7 quarts.

Likewise i suppose, the trans and diff replacement capacities, at 1.8 and 1.4 qts are part of a larger total capacity.

Does anyone have any experience with a total flush of the trans or diff systems?

If so, was it a "Cooler Line Flush" or a "Pump Inlet Flush" based machine?

Is there a filter component that should be changed in the 8 in either the trans or diff?

Finally, what did you use as a system replacement fluid?

I did a trans/diff drain and fill at 12months, and now at 24 months thought I'd explore this option. Thanks in advance for this forums wonderful breadth of experience!!!

Cheers,
Oranje

Not sure what you're asking, but I'll give it a shot anyway. The manual transmission and differential do not have external cooling components like the engine oil coolers. So the oil you drain from them is all there is, save for a minor amount coating the internal parts and possibly puddling in small crevasses.

I use Redline synthetic oils for both. Check the manual for the correct types and weights.

So no need for a flush, since there is no significant residual volume of fluid remaining in the system after the drain plug is pulled.

Thanks. That was the answer I was hoping for.

Oranje

Flushing them would be overkill in my opinion. I certainly wouldn't run something like BG through them in any case. Just drain and refill. Replace the metal washer/gasket on the drain plug, and maybe the fill plug as well if you're a little anal like me.

And don't necessarily go by the quantities listed in the owners manual. Those numbers are just guidelines. Make sure the car is level and refill until the fluid just starts to run out of the fill hole or the level gets to where you can insert your little finger in the fill hole and come (no misinterpretation please :eyetwitch) out with some fluid on the tip of the finger.

I have not make sure, since Royal Purple is not available in my country and my fren will be getting it for me overseas.... Will Max-Gear 75W-90 be the right oil for both tranny and differential or is it another one?

I got it done over the weekend with my brother. Job was very easy thanks to the thread. I used Redline product. Here is my first 100 miles report.

a. Shifting 1st to 4th is very noticable. Best way I can describe is wit the new oil, gear feels like if it is soaked in water compared to sludge(Thinner Oil?)

b. On 5th and 6th gear, the car is able to pickup speed faster at lower RMP. Before the oil change, I end up lowering the gear at certain speeds but now I can press the gas a bit and car pickup speed without shifting.

c. Shifting up to 4th gear, I can feel the gear clunking in often.

Overall, I am very glad I had the oils change. Only down side is I have to relearn clutch/gas/shiting action a bit.

Nedor

Holy cow that has to be messy... :)

Any truth to the fact that the synthetic fluids might not be good for the car, or is that JUST engine oils? Any disadvantages to going to synthetic??

I'm very intrigued by this fluid swap by the way all you talk about the results with Redline.

The only question about synthetic fluids is for engine oil (even that is really up to debate, just read some of the threads on here). There is nothing different about the differential and transmission on this car than those on most other cars, so synthetics won't harm them in any way. Anybody that tells you synthetic will damage our tranny or diff is a bonehead.

Ok I ordered the crush washers from the dealer and purchased redline MT-90 & 75W90 in addition to a oil pump. I will being changing the trans/diff this weekend and will post my comments (hopefully it will make that pesty 5th gear grind go away!).

Done! MT-90 & 75W90. Had the dealer do it; provided them with the Red Line. Also had 245/40's installed at the same time. Alls I can say is WOW! Talk about smooth! Actually sounds like the entire drivetrain is mush quieter now. No issues with relearning the whole clutch/gas/"shiting" process. My technique was never perfect; however, with the same technique it now feels like I've been doing it right the whole time. Make sense? Tires are great as well. No more throbbing vibrations. :boink:

Finished the MT-90 & 75W90 about 8 hrs ago (in addition to engine oil and a K&N filter). Redline is great stuff! 2nd gear use to be tough to shift into at higher rpm but now it's smoth!Someone had posted the torque specs for the drain/fill plugs in Nm (Newton meters) so I had to convert it to ft. lb. which converted into 20 foot pounds (roughly) however, the plugs from the manufacturer were below 20 ft lb?!?!?!? I put on the new crush washers and torqued them at 20 anyways and they were fine :)

Thank You, Everyone!

I did the transmission and rear diff fluid change and the process was VERY easy. One thing that was odd on my car, my bolts to the rear diff where somewhat loose. No leaks but they where very loose.

Right out the back, the car was MUCH smoother in driving. None of the jerkiness as before.

Keep up the good work!

P.S. I called my local dealership and they wanted almost $600 dollars to replace the fluids and spark plugs. Doing it myself, I was able to save $380 dollars.

I've got 17k miles on my 2004 RX-8

Why and when would I want to change these fluids? I've had many cars that I've owned 50k+ miles, and NEVER had to think about these fluids.

Is there a performance gain? Is there high wear on these 8's? Someone give me the 411.

Several reasons.

Some people elect to change these fluids in the first 3,000-5,000 to flush metal debris from construction and wear-in of the gear boxes. The magnetic bolt in my transmission had collected quite a number of metal particles when I changed at 3K miles.

Some people prefer the feel of the synthetic lubricants (like Redline MTL or Royal Purple) in the transmission. It is subjective, but IMHO the Redline MTL made a big difference in the feel of my RX-8's shifting.

Mazda recommends changing these fluids after 48 months or 60K miles.

I've got a leaker! It's been two weeks. Nothing until this weekend. She sat from Fri night through Tues morning. Had a little puddle below it. I'm guessing a tablespoon, or so. Wiped it all down, and am letting it sit to see if I can locate the source. Will update this when I find it.

All and all, I'm very happy with the switch.

?... I left the dealer with a CEL. Check all I could w/out a scan tool. All "looked" fine. Reset it. Week later, and it's back on. Gas cap is fine. :) Any toughts? Can the 8 detect low diff fluid? Did it originally detect it when they changed fluids? Thanks for any input to this one.

MD


Added: Just checked it. Only place it's leaking from is the loose fill plug. What Knuckleheads!!! How hard is it to tighted a freakin bolt?!? Right now my dealership's techs are 0 for 3. (Service advisors are great!)

1. LOST MY WHEEL LOCK INSIDE THE ENGINE COMPARTMENT/SCRATCHED THE INSIDE OF MY HOOD.
2. DAMAGED ALL OF MY WHEELS WHILE INSTALLING NEW TIRES.
3. LOOSE DIFF FILL PLUG LEADS TO FLUID ON MY EXHAUST AND GARAGE FLOOR. CEL MUST SOMEHOW RELATE TO THIS.

Bummer.....

Back home from the dealer. I talked to the service manager & asst manager about my problems. They appreciated the feedback. Seemed impressed that I wasn't out to get them, just make them aware of what had happened. They provided a free complete detail package for the concern. They're still my service department of choice. Service techs will be talked to about their lack of attention to detail. Wheels are repared to like-new-condition. I cannot tell anything happened, even by touch.

Pertaining to this thread: CEL wasn't caused by low diff fluid. Gasket on gas cap was "bad." Of all things. I guess my eyes aren't within Mazdas specs for inspecting that. They replaced it. Need to get me a scan tool.

Still loving the fluid change!!!