goose guy

I'm going to change manual trans and diff fluid tomorrow. Thanks for the comprehensive DIY. I was going to use Motorcraft manual fluid but it cost $27/qt vs. $13/qt for RL MT90, so I cheaped out and went with the RL. If RL is good enough for Ash, then it's good enough for me

ASH8

Thanks I guess.

In fact I just did my MX-5, sorry Miata, a few days ago with RL MT90 and the RL Diff 75W90.

We are in the middle of a cold winter (no snow), but was amazed just how cold the trans oil was during drain after 48 miles of constant driving...just goes to show how outside temps influence internal gear oil temps.

Anyway, why I like RL, it is a great all rounder, naturally performs at it's best when Trans is hot and temps are hot.

Like my RX-8 with basically the same Trans internals I changed original gear fluids at around 1000-1500 KMS (600-1000 miles), refilled with Redline products, and then changed again at 10,000 KMS or 6,000 miles... I did my 8 again @ 30K, Yes it is sooner to what the factory change recommends, but I have had NO issues with either of my trans..

In fact at the 30,000 KMS (18,000 miles) the RX-8's old oil was still very clean, with very little metal (swarf) on drain plug magnets.

As I have said time and time again, these trans take a long time to run/wear in, the proof shows after my second RL fluid change and absence of metal on RX-8 drain magnets.

Yeah it is not scientific, but I will bet my Miata gear oils are the same at 30K,.....very clean.

Plus the good thing about RL is a great product that is relatively inexpensive and I can change gear oils more often, sorry but 80,000 (60K) is just too long to change gear oils from new...one time at Mazda we would ALWAYS, always, change the Trans and Diff Oils at first service (1000 KMS, 600 miles).

MY Gear changes are excellent...I LOVE these boxes..

Sorry for the rant, that is me, I get carried away..

Iluvrevs

I will go back to the RL after this fill of the MC in about 15-20K miles. The MC fell off for me a little at the track last month.

Ash, I saw on Castrol's and Valvoline's AU sites that they spec 75w85 there. Is this in line with the OEM? Why dont you go with that since RL does make that grade?

goose guy

Fluid change was pretty simple, except that I had to run to the auto parts store for a 23mm socket and extension for the diff fill plug.

My car has 26k miles. This is it's first fluid change and I definitely feel the difference when shifting.

Orthonormal

The US shop manual specifies 75W90 GL-4 for the transmission.
(75W90, 80W90, or 90, GL-5) for the differential)

Mr.ThunderMakeR

Sorry I haven't checked in on this thread in awhile, its fixed now.

Iluvrevs

Looks like the AU market is getting spec'd 75w85 from conversations with the 2 oil Co's there. So, Im going to try this in my next OCI next year since I have RL MTL and RL MT90 sitting around and RL used to spec mixing the 2 to get a 75w85.

ober

do you need the torque wrench to tighten the bolts? that seems like a bit of a newb question but i don't have one!!!!!

paimon.soror

iTrader: (15)

it is prefferred ... but you dont need one

Orthonormal

The threads in the transmission housing are aluminum and the plug is steel. If you over-tighten the plug, you can damage the threads in the housing or strip them out completely. On the other hand, the plug could leak or fall out if it is too loose. You can get a torque wrench for I'd guess $30 at Harbor Freight or $75 at a hardware store. It's definitely worth it if you plan to work on your car. The same issues apply to the oil plug and filter when you change the motor oil.

ASH8

OH good grief...you don't need a torque wrench to tighten up fill and drain plugs!..

You have 'crush washers' to seal plugs and 'technically' the washer should be renewed every time.
Just tighten up Plug firm and then again tighten up about 1/4 of a turn, no more, that is it.

If you believe a TW is needed then I suggest you find someone else to do the work...no offense

Blacknightz

thank u.... perfectly done

Orthonormal

I like to do things by the book. I've run across too much screwed up work done by people who don't. Too often "professionals" with a careless attitude.

I'm going to just ignore your insinuation that I'm technically clueless. You don't know me.

Of course not.

ASH8

/\ I am telling you NO 'professional' with or without a careless attitude uses a TW to do up any Oil Filler or Oil Drain plugs...they would be laughed at.

Beefy98

I wanna go back to the stock fluid instead of the Redline I have now. So its Ford Motorcraft GL-4 and its synthetic? the 2nd pic was something different..


And the OP says to do it at 48k...I coulda swore the manual said 30k for severe and 60k for normal.

adambomb

I am going to change my Manual Transmission Fluid and my Rear Differential Fluid on my 2009 R3, but there seems to be a lot of random opinions all over the forums. I want to get some clarification from the more experienced people here:

Manual Transmission: 75W90 GL4 (2.04 US Qt)
Rear Differential: 75W90 GL5 (1.4 US Qt)

Options:

Redline MT90 for the Transmission.
Redline 75W90 GL5 for the Differential.

Although......
BHR recommends the Eneos 75W90 GL5 Gear oil for the Transmission and the Differential, but the oil explicitly says to not use in a a LSD differential (For use in any manual transmission or differential (NON-LSD) requiring 75W-90 & GL5 viscosity).

Eneos 75W90 Gear Oil | Black Halo Racing

Can anyone clarify what really should be used? I have read that people "Like" this Eneos brand, and Redline seems to be a safe choice, with the Ford option as an alternative with reputation of use on Miata's.

Main take away here is that I don't want to ruin my synchros, my differential, but I want good shifting performance in a relatively hotter climate (Texas).

adambomb

I have seen a few different part numbers, just wondering if someone has the Transmission drain/fill washers, and the differential drain/fill washer part numbers?

Saw some on these websites, just wanted to confirm:

Series 2
RX-8 - 2009 + - Drive Train - Rosenthal Arlington Mazda Parts Store

Series 1:
2004 RX-8 Transmission & Differential Refill

Mr.ThunderMakeR

You are right, I accidentally quoted the KM number. I'll fix the first post. As for stock fluid, I have no idea what the stock fluid is. Best way to figure out would be to call a local dealership. Ford Motorcraft is what is recommended by NC Miata owners, who have the same transmission as S2 RX-8's. Honestly either the Redline MT-90 or Ford Motorcraft FSMTF should be fine, with the Motorcraft maybe having slightly better cold temp performance.

Not sure what you mean about the pics being different. The pics show Ford Motorcraft FSMTF (read the bottle)

Do NOT use GL-5 type oil in the transmission. It should strictly be GL-4.

Sorry can't help with this. I would say just go down to your local dealership and pick one up. Compare it with the old one when replacing, make sure its exactly the same.

adambomb

For the Series 2 RX8:

Manual Transmission Fill / Drain and the Rear Differential Fill Crush Washer = Part # 995641800

Rear Differential Drain Crush Washer (Copper) = 995621800

Prices vary dealer to dealer, online, etc by several $ per washer.
I just purchased through Mazmart as I needed other parts too.

I am making sure I have a set ready to go when I change the fluid, just in case.

xexok

I just changed my transmission and differential oil tonight. The bolts on both were just under 15/16(was a bit loose), but definitely bigger than 21mm like this post said. I even had a 22mm socket and it was too small, I'm thinking 23 or 24 would have done it but I didn't have those.

Seems strange that it would not be the same size bolt for that on all the series 2's.

2009R3

iTrader: (1)

I'm preparing to change both my transmission and differential oil and picked up some Royal Purple MaxGear. It's a synthetic 75W-90 that is rated both GL-5 and GL-4.
Anybody used this stuff or have an opinion on it? It feels strange to put the same oil in both my diff. and trans., but the label clearly states that it can be used for both.

R3Screamer

For any of you who are doubting the Mazda OEM 75w90, it is gl-4/gl-5 compatible. I was worried about this as our transmissions, call for only gl-4, but I called multiple Mazda dealerships, and this is what all stock for RX-8s. They said it has the properties of a GL-4. Miatas use it too I think. So as far as RWD transmissions, it's safe. Gonna put some in today at work.

Nadrealista

So for track use is redline >> motorcraft transmission fluid in S2?

What about diff fluid?

What about Motul, has anyone used it in S2 tranny, it worked well for me in S1 tranny?

https://www.motul.com/system/product...pdf?1290086772

bulletproof21

Redline MT -90 for tranny, Redline 75W90 for diff

Quino

Does this oil compartment lubes the clutch mechanism too?