Ok so im pretty much on my third transmission. 1st tranny synchros were rebuilt around 40k miles 2nd and 3rd. Then that tranny went out 10k miles later it started doing the same, so mazda put a used tranny in my car to replace it. the tranny had about 48k miles on it when put in. As soon as i got the car back i could already feel grinding in 4th and 5th gears. Now i had a new motor and the tranny put in at the same time, so i just got the new motor broken in about a month ago and yesterday i decide to change the transmission fluid, and it was like black water. I add in the new redline oil, and now 4th gear grinds even worse than b4! Now anytime i shift it grinds to where it used to be just at higher rpms and now at high rpms i can barley get it into gear. Why would that be? its not low on oil i dont get it! So ill be taking my car in to mazda now and either they will rebuild this one or maybe finally put a brand new one in it.

 

What grade tranny fluid are you using?

 

they probably didnt install it right.

 

You mentioned Redline Transmission Fluid but I'm sure hoping that you didn't use anything besides MT-90 in your transmission.

 

Me, MT-90 in Tranny.

Me, Happy.

 

actually i thinik it is the ns so should i drain it and put in the mt, or just take it to the dealer and have it fixed?

 

Yes, NS doesn't have any modifiers that your transmission need. That is the reason why it's grinding so much, I'm guessing that you're using 75w90NS (well, it's bad to use anything that has NS in it), that's a bad thing to do since it's lacking GL5 along with other modifiers.

It is HIGHLY recommended for you to change it out and use Redline MT-90 instead before you destroy your synchros and gears.

 

stop drag racing so much. :P

 

err...

the NS means its a GL-5 fluid but without the fiction modifier for LSD.

so it could be use on tranny but I prefer GL4 over GL5 for transmission anyday. use MT-90.

 

could it be broken clutch pedal bracket?

 

You want GL4. My first transmission died after prolonged use of GL5 maxgear.

 

No its not the clutch. its only 4th and 5th gear. other gears shift wonderfully. I havnt even been racing it sinc i just got a new motor put in and just broken it in! So i should switch it to mt90? or should i just go ahead and take it to the dealer? either way it seems the synchros are startin to go.

 

take it to the dealer first, since there is no way they can tell what kind of fluid u have in there. Actually when they try to drain it they will probably skip the "Have you did any maintenance to your transmission fluid?" as its gonna look really new.

 

So you want MT-90 in the tranny. what goes in the diff? Same thing or the 75w90ns?

 

...

MT-90 in tranny,
http://www.redlineoil.com/products_g...7&categoryID=7


For rear Diff, do NOT use 75w90ns. Use the regular 75w90.
http://www.redlineoil.com/products_g...5&categoryID=6

 

Thanks for the info nycgps.