Differential fluid options... looking for better opinions.
 

Hey guys,



Ive being reading up on what fluid to put in my Diff.

After searching and reading for 20 minutes on the forums i came to the general concensus that people use 75w-90 in various brands. However i dont really trust jo-blow and bobs advise on this one.

However the FSM says:

DIFFERENTIAL:
Grade: API service GL-4 or GL-5
Viscosity (Below 0F): SAE 90
Viscosity (Above 0F): SAE 80
Capacity: 1.38 US qts


I tried looking around for SAE 80 today but no luck. I guess its a mazda fluid...


So i guess my question is.. what oil be compatible with the factory LSD and such.



I would like to hear from you experianced guys out there.



Thanks in advance.


=Ben

For an FD?

Get Redline 75W90NS assuming you have the stock Torsen.

You can get a lot of diffrent responses, i use royal purple trannie and diff. I run the clutch style t11 and royal purple has the clutch aditive for the diff. Some like neo. With a 1.52 60 ft i cant complain, stock components and still holding up!

Use NEO gear lube. Buy a gallon and it will fill both your tranny and diff.

I still believe in the redline MT-90 for the tranny, 75W90NS for the torsen.

Amsoil 75w90.

2.6 qts for the tranny, 1.6 qts for the diff, IIRC.

http://www.amsoil.com/storefront/svg.aspx

Find a decent synthetic lubricant rated 75W90 which you can buy locally. I use Royal Purple as the local NAPA stocks it. If you have Redline, Royal Purple or any of the other big names locally, use it.

Neo ftw.

Better opinions that what?

Since these cars are 15 years old and (short of 400+ whp drag runs with slicks) differential failure is pretty much unheard of I would guess that there is nothing new to be learned here. Any common suggestions you read on older threads should be perfectly valid.

Negative.


I do not want premature LSD or diff failure. I want the RIGHT oil or damn close to it, not whatever jo-blow says. Most people are too lazy to be bothered with doing a little research so they just assume things... "oh ya im sure this stuff will work fine... im not going to mazda to get the right stuff." Assumption is very closely related to ignorance, and ignorance is a dangerous thing.





What is this 'diff/lsd' additive i keep heaing about?



Well the Royal Purple 75w90 i just bought for my tranny does say 'Limited slip' on it. And the other side of the bottle says "Contains limited slip additive", so obviously i guess Royal Purple formulated this gear oil for LSD differencials/trannies.



Thanks to everyones comments, greatly apreciated.



=Ben

Spare me the tiresome condescension. Are you familiar with the work 'empirical'? These cars have been around since the early '90s and many have 150k+ miles on them and most of these cars are treated pretty badly by people who can't afford to maintain them. Yet, premature differential failure is pretty much unheard of. Any person with an IQ above 50 should be able to conclude the obvious. You need to find something else to worry about.

Well my car has 76000 original km's with full service records... I would like to keep it as mint as possible.



Most empirical advise is without MUCH experiance, refer to first post "I would like to hear from you experianced guys out there."


As far as worring, it is obvious that you have nothing to do with your time then to flame posts... you need to find something else to DO!! Ive read all of the old posts about this topic, and i still wanted better opinions after reading those, obviously they were not sufficient.





Anywho, thanks for all the USEFUL posts from the rest of you fine members.



=Ben

The aditive i was talking about is for clutch style diffs like the t11, the torson does not need this aditive but royal purple has it any way. I have been abusing rx7's for 8 years and yet to break a diff but 1.52 60 ft times is pushing it.

i use idemitsu 75w90
i havent used anything else but i believe its ideal

pretty much any 75w-90 gear oil from reputable company's will be ok. your diff isnt going to fail because you used mobil 1 75w-90 instead of neo 75w-90. get the viscosity right and it will be ok

i used neo in the past and have no complaints. however im switching to motul just to see how that goes.

Fortunately torsen diffs are robust in their compatibility with gear oils. I'd put any of the oils mentioned so far in my diff. The fact that so many people use different gear oils without major issue testifies to the fact that they're all good products. Without a special dyno or going into the ASTM tests, they'll be the same.

SAE 80 is a viscosity. So 75w-90 is a valid viscosity for a diff. If you typically do heavy track work that really builds high diff temps, consider a 80w-140 so that it's not too thin at operating temperature.

I believe the most important property aside from viscosity is the EP additive package. You might consider something like Redline Shockproof series and change it every 10k or 20k if you are vitally concerned about it. If you want to get hardcore, head over to the bobistheoilguy.com and ask about torsens.

For clutch-pack (Posi) differentials. It modifies the friction properties so that the clutch packs have more grip than they would in plain gear oil. More friction modifier, the more strongly the LSD responds.

In a torsen, the mechanical friction of the worm gears is what causes the traction in a turn. I'm not sure in a torsen what effect ls additive has, how much to use, etc. Mazda doesn't specify it.