Alright so I looked at the do it yourself thread for changing trans and diff fluid, and I plan on doing it soon. My only questions is, what's the best fluid to use? In my Cobalt SS I used Mobil One trans fluid, would that be okay to use with this car? I understand it needs 75w90 as well, but is there a special type?

 

m1 should be fine im like in the enos though from what i been reading but its expensive but
royal purple from what i read it likes to eat our trans up cause of the metals our trans are made of so
i wouldnt do that sry for hittin royal purple in the face hahha my opinion

 

Try the Oem grade from royal purple

Mod edit: DO NOT USE ROYAL PURPLE IN THE RX-8's TRANSMISSION!

 

Royal Purple makes an OEM grade?
And haha what's Enos?

 

Start reading the new owners stickies to get a better understanding of the car and engine.

Eneos- Blackstone Labs Eneos 75w-90 UOA | Black Halo Racing

 

I recommend against Royal Purple's MaxGear (or any GL-5). I'm guessing there's a reason that Mazda changed the transmission fluid recommendation from GL5 to GL4 starting around 2006 (Check out page 10-4 in the owners manuals for the 2005 and 2006 model years on Mazda's website; 2005 says GL-4 or GL-5 but 2006 and later say JUST GL-4).

 

Holy damn that's expensive fluid, what do people commonly use beside that? I heard something about the redline gear oil? And I'll make sure to go through the thread again to learn more about the car.

 

You asked for best you got best.

 

Redline is pretty good, I noticed a pretty big difference using it in my transmission and diff

 

*Like

 

Oh definitely lol, is it worth it though? And it is that much per quart?

 

The lesson you should take from this is- do your research. There is a lot of info on these forums. Start with the new owners thread, and work your way from there. In the very end, your OWN opinion (based on your research) is what will ultimately lead you to your decision.

 

My favorite in my last Mazda (MX3) was AMSOIL GL-4 with a couple ounces of Lucas transmission treatment to thicken a little for better coating and shock prevention.


My new RX-8 had 33K miles and shifting into Reverse and Sixth was tricky. Put the AMSOIL GL4 and Lucas in, and she shifts quietly and like butter. I also put AMSOIL GL5 into the rear diff, with about an ounce of Lucas. Feels great.

 

Personally I use Redline and love it. For both transmission and differential fluids I believe it was somewhere around the $100 mark including new crusher washers; I'd highly recommend it.

 

DO NOT USE ROYAL PURPLE IN RX-8 TRANSMISSIONS. The syncros WILL fail. It will feel stellar for a few thousand miles until your syncros self destruct. It's the wrong oil type.

 

I like Amsoil products. Redline feels awesome at first but for me got worse over time.

 

Hmm so from what I gather, besides Eneos Redline and AMSoil are the best? I have a 2005 so I need GL-4 compliant fluid, not GL-5, is AMSoil GL-4?

 

Oops I found my answer haha, I skipped the reply where it explicitly says it's GL-4 :P

 

Alright just ordered 3 quarts of Amsoil, hopefully I'll get to changing my trans fluid this weekend, I read through the paperwork the previous owner gave me and the diff fluid was already replaced about 10k miles ago.

 

Thanks for the advice. I tried it on my first rx8 but I got involved in a hit an run a few weeks later and during that time it felt great. But fixing know over time it would destroy my syncros.

 

I just changed my tranny fluid using Eneos. Ive been using it for two years now. I was using Redline before but it was still notchy even after a fresh change. Eneos = Buttery Smooth

 

Haha I wish I could afford the stuff, the cheapest I could find it was about $85 per quart, unless that's for a case? It would make more sense.

 

i switched to redline mt90 in the trans at 50km, started off fine as Arca_ex said but now when cold 2nd & 3rd are difficult to engage. there was talk of a 60:40 mix with redline MT90/MTL that guys were saying was buttery smooth. Not sure whether to venture down this path or may be able to get some Amsoil but we dont get Eneos here in NZ.

 

Im in the same boat being a kiwi. Im running mt90 now and it seems pretty good (only 250ks though)

 

mine was good for about 2,000km an then 2nd & 3rd gear starts to not want to go in on upshifts for about 10-15 mins till it warms up. once its warm its no issue at all in every gear, just a hassle. it just feels slightly too thick, & if you rush the shift into 2nd by mistake it will crunch..very similar experience using it in my DC5R gearbox actually.