After Clutch Install shop put in mobil 1 synthetic 75w90
 

I searched and around and found conflicting opinions. I heard it destroys brass synchros. I've noticed my trans isn't quite as smooth and its only been about a week. Any have opinions on this. I've already ordered redline mt-90 because quite frankly I just don't trust the mobil one crap. Will a week or 2 of this mobil cause problems?

why would it destroy bras synchros?

from what I have heard about mobile 1 from other auto ppl is it is it is good stuff.
a lot of ppl ho decide to go the synthetic route a lot of times seem to put all mobile one in there

it's not bad stuff as far as I understood

if you have other info though would be welcome to take a look at it

I've read in a few places the gl5 75w90 gear lube has a higher sulfate content that eats brass and other soft synchros. And the tranny doesn't really like gear lube, it prefers trans fluid with a synchromesh modifier. At least thats what I've read and understood. Anyone feel free to chime in and correct me If I'm wrong. It also did a number of my dsm transmission. So I'm just weary of it.

Thats good synthetic...

But if your really worried about it, then drain it and put in Redline or Royal Purple. Its only slightly more complicated than an oil change.

Same thing happened to mine. I should probably change the fluid in mine too, it doesn't shift as smoothly as it used to, especially when cold.

I 've had Mobil1 in mine for about four years now and haven't noticed any problems other than what I already had.I have /had some third gear issues that seem to have mostly cleared up since I put it in.

I went from redline mt-90 to mobil1 75w90, and it did shift slightly harder after. I wouldn't worry about it too much though, you may not even notice the difference.

I haven't heard the sulfate content thing though, but it seems like they would put a warning about it on the package, its common to use gear oil in transmissions.

change it. can't hurt, might help and will probably shift better.

The guy who rebuilt my trans told me to put mobil1 synthetic in it, but I went with redline since no one local to me had mobil1 at the time.

I changed the mobil one out of mine a few years ago after rumors that it ate at the brass parts of the tranny. I havent seen any CONCRETE evidence of this though.

mobile 1 is claimed to exceed gl5 specs
redline also give the same claim as far as exceeding gl5 specs for its 75w90 weight oil
so both there claim to be the same

as far as the tranny not liking gear oil
that is what a tranny is
a big bunch of gears
but also the mazda owners manual says to use 80w- something weight gear oil in the rear and transmission
many cars use gear oil for transmission lubes
as far as the sulfate content I would think that could vary from manufac to manufac though mobile 1 has always been a good name brand of oil to use with their synthetic products

as far as using tranny fluid are you talking ATF? a.k.a. automatic transmission fluid?

only other fluid I know of that can be used inside a tranny cause I never heard of tranny fluid unless yo uare talking gear oil or ATF


btw aren't dsm trannies kinda weak as is?
not sure on that one
but unless you know for sure that it was the oil don't knock it as a scape goat

part of the reason our cars get a bad name
ppl mod the car
don't take care of fuel or other tuning blow the motor
well it was the rotary fault it cause the problem

I think the reason which there's nothing noted on Mobil's oil is because there aren't many cars out there with brass syncros. Ours is one of few, AFAIK.

But whatever... Everybody will have a horror story about something. I've heard people who claim redline synth destroyed their transmissions.

So unless you notice a serious decline in the performance of the tranny and how it shifts, you should be safe.