Just bought 85w140 for my trans I will be putting it in on Sunday. I figure to lose 1hp do to the thickness but will make up big ground in the life of my trans. Hope I am right. Will update if my trans blows

 

uhm

 

just drop in some 1000w12000 and be done with it.

 

1millionw 1billion is better

 

85w140 should make shifting fun on those cold Missouri winter days.

I myself use Redline MT90 which is a 75w90 and my trans has had no issues after 143,000 miles.

 

Well this just proves,, thicker is better.

 

moving to texas a little warmer but no bad feed back yet ?

 

Got rid of Royal Purple and went to straight 140w GL4 and by by 3rd to 4th gear grind and super smooth shifts screw you RP

 

Get that out of there, it isn't designed to work with soft metals/trans synchronizers

if you want to use a heavier fluid the get the Redline 75W140NS. Make sure you get the NS designation intended for trans use as they also make a regular 75W140 for rear differential use

 

It has the NS GL4 and is intended for trans according to the label from oreilly auto parts. I had it out on the road all day no issue but if one begins I wont hesitate to drain it again.
Thanks for looking out however

 

Would a super-heavy lube entrain too much air?

 

Dont know but have thrown down about 220mi so far and my trans in shifting much better then the Royal Purple. My only thought was that RP was way to slick and was F-ing with my sync's. Pops right into gear no issues but if one arise I will post right away. One more point I did notice my trans felt much cooler then before. I kind of feel like I am in uncharted taritory so we will see.

 

one last thing it did say aniti foam so you know we will see

 

FYI, I think I'm safe in saying that the RP gear lube has been widely found to be unsuitable for the Renesis transmission, so you may not have had to go to extremes to get something that works better. Then again I have no idea if your new stuff will cause any problems. Good luck with it.

 

use some glue next time?
or some butter?

 

This may be crazy talk, but why not try conventional gear oil that matches the specs in the owner's manual?

Ken

 

No your right Ken and that was my plan until the only GL4 the auto parts store had was the straight 140 and I had to get the RP out ASAP. Trans fluid is easy to change so if a problem starts I will solve it quickly. there is only one draw back that I see is maby a loss of 1hp do to the thicker oil but I also see two good sides being cooler trans and reduced gear wear. Lets also remember that Mazda did every thing they could to get as many MPG out of the 8 as they could to keep the EPA happy and thin oil in the motor and trans helped them reach there goals, but at the cost of reliability. Just one mans thought

 

When it comes to gears you want the thinnest oil you can use that still does it's job. That applies to all oils though. On gears if the oil is too thick, it won't get to the bottom of the teeth and that's where the wear will be. If the oil is too thin there will be little wear at the bottom but all on top. Why are you running that stuff? Thicker is NOT necessarily stronger or better. Keep in mind that gears have different lubricating requirements than bearings do. Bearings need a more robust oil than gears! Viscosity is also not measured the same between engine oil and gear oil. 75W in gear oil is not 75W in motor oil. It is actually about 15W! An 85W gear oil is equivalent to a middle of the road 30W motor oil.

You are going to get a couple of things out of running that oil. Your transmission temps will go up. Your parasitic losses will go up. Your gear wear will go up.

 

Trans and diff fluid from the dealer has worked just fine in my tranny with 110,000+ miles on it. Don't believe the hype.

 

Well 400 mi now no problems feels great but seeing as Rotary God had to chime in and destroy my party I better change it out this weekend affter all he knows a little more then me...... well a lot more. I just wish you would have jumped in a little sooner but thats all right more quality time with my 8

 

+1 on the MT90. I have been running it for 25k miles with no trouble (the factory gear oil gave me a grind in third)

 

You don't have to take my word for it if you don't want to. I have an opinion like everyone else. I do know that of the 5 RX-7's that I've had that they've all been fine with 75W90 with a couple of them topping out over 200K miles on the original gear oil they came with! I actually do recommend changing it sooner btw. Contrary to popular belief there is nothing special about the RX-8 transmission over the older ones. At least not when it comes to what oils work or don't. A Honda transmission on the other hand...

 

^
this is what I love about this club everyone working as a comunity to keep as many 8's on the road as we can.

 

We don't believe your claimed HP hype, which likely exlains why it works fine for you and everyone else breaks

the FD3 trans is only a 5 speed and is well known to be stronger than the RX-8 transmission



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