blandry23

i have an 83 and an 81 gsl. both 5 speeds. i want to try and put penzoil synchromesh in the trans but ive been told that its specifically for brass synchros. do both the 81 and 83 have brass synchros? just something i figured i'd ask before putting the stuff in. oh, and also, where is the filler plug on the trans? ive seen a bolt on the drivers side on the side of the trans, but i wasn't sure if that was it or not. any help will be appreciated, thank you.

mazdaspeed7

Nearly all synchros are brass, and gear oil in general is designed to work with synchros. Its a marketing thing more than brass synchros need anything special.

If it hasnt been done in the last year, its a good idea to change out regardless of what brand oil you use.

http://www.synthetic-oil-tech.com/Ge...te%20Paper.pdf

Thats a very good read on gear oil.

The drain plug is on the bottom of the trans in the middle, and the fill plug is on the drivers side about halfway up. The trans will take approximately 2.6 quarts to fill from empty, and should be filled until oil just starts to seep out of the fill hole, as the car is sitting on a level surface.

j9fd3s

fill plug comes out first, its a 14mm square head.

after trying nearly everything over 15 years or so, i actually just use plain old atf in the trans, it works great, and its easy and cheap.

blandry23

crap, i underfilled it. i put in two quarts of lucas heavy duty gear oil. i saw that the haynes manual said 1.7 quarts, so i just put the two in. i really couldn't put it on a level surface, it sat on jack stands as i drained and filled it. i almost cried when i drained it. the oil was dark, but also was very goldish shiny. im guessing thats my synchros. i think the synchro for 4th gear is shot. the car will shift into 4th sitting still but will not at speed. i thought at first that it might just need new fluid cuz i figured that it wouldn't shift into 4th at all but im pretty sure im sadly mistaken.

@mazdaspeed7: thank you for that link, it was quite helpful and actually surprised me. i didn't read the whole thing, but looking at the graphs and intepreting those showed me everything i needed to know. its funny that so many people swear by royal purple, but it turned out to be the worst. it breaks down way to quickly. i was actually thinking about putting royal purple into my diff and trans. good thing i didn't. like i said, i have a lucas non-synthetic in my trans, next switch i'll look to get some high grade synthetic for both my diff and trans. the more i read this article, the more i see how misleading some of these products are. im not going to use lucas in my diff or trans anymore after what i just read. it is heavy duty like it says but it sucks in every other category and eats copper. thats not cool. amsoil it is from now on lol.

jd: ive heard of people doing that but is the atf safe to use for the synchros? i know its supposed to make for less resistance but i wasn't sure about doing it.