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Factory fill on trany and LSD

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Old 09-25-2003, 03:37 PM
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? Factory fill on trany and LSD?

I dont have my manual at work with me....does anyone recall what the spec lube weights are or factory fill for the trany (6MT) and the LSD?

thanks....

Last edited by wleonard; 09-25-2003 at 04:18 PM.
Old 09-26-2003, 04:18 PM
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ok?
Can anyone recommend the best brand of Synthetic gear oil to put in the LSdiff?

Thanks...
Old 09-26-2003, 11:16 PM
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from the manual:

manual transmission api service gl-4 or gl-5 (sae 75w-90)

rear diffierential oil api service gl-5 (sae 90)

I'd like to hear more expert opinions on synths in the mazda gearbox (it is oem mazda, right?) and in the diff before going that way.
Old 09-26-2003, 11:17 PM
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6MT 1.8 qt
Diff 1.4 qt
Old 09-27-2003, 12:25 AM
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I don't care to get involved in the age old religion of synthetics vs dinos - but I'll tell you right off that you want to stick w/ a GL4 regardless only for your tranny in most cases. It will tend to shift better than a GL5 and perhaps bettr than a GL4/5 'combo' oil in most cases.

Good luck finding a pure GL4 though - hard stuff to come by these days and that's probably why Mazda compromised and listed the GL5 option too. Some possibilities pure GL4s include Redline, StaLube, Nissan.

(Oh and never never ever put GL4 in a differential!)

Most GL5s have the necessary friction modifiers for a limited slip so there's a million choices here at any local store.

This is a change you may want to consider fairly early on in a car's life and then after that the changes can follow their recommendation which is probably few and far between. The first change will be good to get out any metal particles from the fresh new gear parts which is normal. There are probalby magnets in teh drain plugs as is typical for many Japanese cars that may have some metal that needs to be cleaned off as.
Old 09-28-2003, 09:10 AM
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...thanks all around. Exactly what I needed to know.
Old 10-07-2003, 06:57 AM
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Try Redline MT90 in the manual transmission. Other good choices are Neo 75w90hd and Amsoil ALU or AGT.

Any quality synthetic gl5 rear gear oil is better than stock mineral oil. That being said, Mobil1, Amsoil, Neo, Redline, Motul........are some great choices.

The Mazda 6speed gearbox is not Mazda. It is Aisin and is similar to what is used in the IS300/s2000/Miata.....
Old 10-07-2003, 09:24 AM
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Don't forget you have a Torsen-type LSD -- it can make a difference when choosing between gear oils like RedLine 75w90 vs. 75w90NS...
Old 10-07-2003, 10:21 AM
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For transmissions... The MT90 or the ALU/AGTs are pure GL4s. There's only a couple other synthetic GL4s even available. The Neo is (I think) a GL4/5 'combinatin' oil.

You won't find that many conventional oils in a 75W90. That's mostly synthetic. Conventionals often come in 80 or 85W 90.

I wonder who their supplier is and exactly what the factory uses for factory fills?

I didn't realize the rear had a Torsen and I don't know anything about their lubrication requirements. If they dont' require a limited slip additive so much the better for using a lubricant that is unadulterated. But if so, the same problems occur as w/ finding GL4 options. Few GL5s come these days w/o some kind of limited slip additive. It won't hurt to have it but if you don't need it, why adulterate or dilute your lubricant?
Old 10-07-2003, 10:55 AM
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I didn't think GL4 and GL5 were compatible enough that there would be "mixed" solutions or that either would be regarded as OK from the factory in the manual...if the synchros can handle GL-5, why use GL-4? If they can't, why would anyone whisper a recommendation of GL-5 anywhere, much less in the owners manual?

I need to go do some readin', but feel free to edumacate me in the meantime if you can help me understand
Old 10-07-2003, 12:28 PM
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First, keep in mind that GL4 and GL5 are inedpenent standards and one is not backwards compatible w/ another or better simply because it has a higher number.

That is an excellent question but I doubt you'll ever find a definitive answer.

GL5s are 'OK' in a manual transmission. They are not however 'optimal' in my opinion.

Many manufacturers list "GL4" or "GL4 OR GL5" or simply "GL5 for their manual transmissions (many also list ATFs nowadays or other proprietary fluids but that's another story).

I think those makers that list GL4 get it right. The ones that list 'either' are 'fence sitters' and the ones that list GL5 are not doing their owners any favors.

There are 2 issues w/ a GL5 in a tranny - it's compatibility w/ yellow metals(synchros) and it's being typically too slippery for 'smooth' shifting. A 'combo' oil that is certified for both will certainly be compatible w/ yellow metals in a tranny. That is one issue you can put to rest w/ a 'combo' oil. That is REQUIRED by the GL4 standard. However they will likely be pretty slippery and may still possibly result in slightly notchier shifting - that is NOT specifically called out in the GL4 standard AFAIK and this is probably where you may or may not find a compromise in a GL4/5 'combo' oil performance. It is for this later reason that I prefer to go w/ a pure GL4 and not a GL4/5 'combo'. Note that there are variances between trannies - some synchros are more tolerant of slippery GL5s than others so this is definatley a case of YMMV!

For those makers that list GL5 for their trannies - dunno. I think they either don't sell a GL4 product and dont' want to add another product to their line or they don't want to hassle w/ the potential liability of some idiot putting a GL4 in a differential (which IS disastrous).

Remember a GL5 in the tranny will work 'OK'. It will likely be a bit 'notchier' and over a very very long haul may or may not be detrimental to yellow metals (synchros). SOme newer modern GL5s are friendly to yellow metals but traditionally they haven't been. Whcih is which - I have no idea!

Like I said there is probably no definitive answer as to why some makers spec GL5 for their transmission - I can only conjecture. But if anybody has any specifics - I for one would like to hear it.
Old 10-07-2003, 12:42 PM
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DAMN, so I need to drain the GL4 out of my LSD??!!

Just kidding.

I'll look for a pure syn GL4 for the tranny or settle on a dino pure GL4.

For the LSD, I shouldn't have much problems finding a good syn.

Thanks again.

Post more info if you have it, cause Im draining soon!

**note to self: no GL4 in rear

Last edited by wleonard; 10-07-2003 at 12:45 PM.
Old 10-07-2003, 12:58 PM
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Heh heh, I hope so!

I could only find two GL4s in my area - StaLube 85W90 conventional (NAPA) and Redline (also readily available online) MT90 from a local speed shop.

Amsoil makes a GL4 only - don't be fooled by it's 'Marine' label - its identical to their other one - buy it in qt or gallon I think. Problem is most Amsoil salesman want to get you to buy into the multi-level marketing thing and they also try to sell their pricier GL4/5 'combo' stuff. I have no experience w/ their oils.

Pennzoil/Quaker (same) have a synthetic Gl4 - good luck finding it - you won't 'cept maybe by the case at a hideous price nearly double or triple redline. (if anybody does try this liquid gold - I'd like to hear about it!)

I think Pennzoil Valvoline and Chevron also make conventional GL4s but they are very rare and obscure substances that are probaby only sold in bulk as well. Like some manufacturers themselves, the oil companies appear to have walked away from this standard unfortunately.

That leaves normal DIYers w/ only Redline, StaLube or perhaps Amsoil (if you have a cooperative salesman). The Amsoil synthetic GL4 in 1 GAL seems like a relative bargain. Redline MT90 has a legendary reputation.

===

For the more adventure, there is also Redline MTL a 'lightweight' GL4.

And if you want to go lighter still there is GM/Chrysler 'Synchromesh'. This is heaver than an ATF 'might' be similar to or lighter than MTL. It is not technically GL4 as it meets proprietary standards for manual transmissions. But it is for a manual tranny afterall and I suspect is essentially GL4 compliant (I'm guessing). I don't know how safe or compatible it would be in other trannies but I hear antecdotal data that suggests it's great (like an MTL).
Old 10-07-2003, 01:57 PM
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What is the conclusion on the oil for the LSD?

If I were to order Redline's, which one should I be getting? The 75W90 (with modifiers) or the 75W90NS?
Old 10-07-2003, 02:59 PM
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Originally posted by MSMAMBA
What is the conclusion on the oil for the LSD?

If I were to order Redline's, which one should I be getting? The 75W90 (with modifiers) or the 75W90NS?
Straight from (one of) the horse's mouth --
From: Dave Granquist <NOT_SHOWN_IN_FORUM@redlineoil.com >
[...]In your Torsen differential, I would recommend the Red Line 75W90.
The Torsen doesn't need the friction modifier that the 75W90 contains, but it is beneficial as it reduces friction and temperatures on the hypoid gear.
Hope that helps.
Old 11-03-2003, 03:04 PM
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Synthetic engine oil is often debated. However, there is no debate on tranny and LSD oil -- synthetic is better.

I use Mobil 1 on both tranny and LSD bc it's the easiest to find and cheaper synth lube around. Neo, Royal Purple are all great but hard to find. I rather not pay to have oil shipped bc it's heavy and expensive to ship.
Old 11-03-2003, 07:40 PM
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M1 does NOT provide API GL-4 service levels. Some car makers (including Mazda historically) specify EITHER a GL-4 OR a GL-5 for their manual transmissions. Mazda probably recognizes taht GL-4s are next to extinct but I also think it's a bit of a cop-out on their part. Nissan still sticks to their guns last time I checked and only specifies GL-4 as it should be for transmissions.

Regardless a pure GL-4 is superior than GL-5 in a traditional sychronized manual transmission.

The choices in pure GL-4s is sadly limited these days - you can find Sta-Lube GL-4 in dino and maybe Pennzoil Marine GL-4 in dino in various parts stores.

But for a synthetic GL-4 there are simply none to be had marketed as convenient over the counter products widely available. Visit most any 'perofmrance' or 'speed' shop and there is a good chance you'll find Redline MT90 GL-4 synthetic. I have several such shops in my city and it is priced within a buck or so of M1.

There are some other synthetic GL-4 options out there but not convenient (Amsoil) or appropriately priced (QState/Pennz).

There are also GL-4/GL-5 'combo' oils - I feel these are still a compromise - they offer the protection against yellow metal corrosion needed for many transmissions but still do not offer the smoothest shifting compared to a GL-4 in some transmissions in my experience. Transmission 'feel' is a subjective thing so YMMV.

Keep in mind that some modern manual transmissions for a variety of reasons now increasingly spec various 'ATF's or proprietary fluids though I don't think Mazda has gone that route as of yet.

Were I to get a new car such as an Rx8 - I personally would probably deviate from the normal service schedule and change the box fluids very early on and get rid of the normal metal powder that forms in any gear set early in it's life. I'd probably do it at 2 to 5K miles or so I guess. Beyond that I would just stick w/ normal extended periods per the manual. Mazdas like most cars usually have magnetic drain plugs that should be cleaned when fluid is changed.
Old 11-05-2003, 02:27 PM
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torque spcifications?

(hijack alert!)
Anyone have a service manual that can quote the torque specs for various bolts? In keeping with this thread I'm interested in the drain and fill bolts for the MT6 transmission, differential, and the engine drain... -jd.
Old 11-05-2003, 04:41 PM
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Originally posted by pgtr

And if you want to go lighter still there is GM/Chrysler 'Synchromesh'. This is heaver than an ATF 'might' be similar to or lighter than MTL. It is not technically GL4 as it meets proprietary standards for manual transmissions. But it is for a manual tranny afterall and I suspect is essentially GL4 compliant (I'm guessing). I don't know how safe or compatible it would be in other trannies but I hear antecdotal data that suggests it's great (like an MTL).
Question regarding this.. Afaik, the GM synchromesh is similar to a 10w30 weight? I've used this in my Preludes' manual tranny and it didn't look like a 75w90... so would it be safe to use in the RX-8's tranny ?

As for "performance" the GM synchromesh so far is working well, tranny is smooth, the real test will be in the upcoming winter.
Old 11-05-2003, 05:33 PM
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You may already be aware of this but gear viscosities are not on the same scael as motor oils.

Yes, it equates to about a 5W30 in motor oil.

But a 75W90 equates to 'about' 15W40 or so in motor oil. The difference may not be that obvious to the naked eye at room temperature.

There are several Synchromesh fluids. GM has 3 I think: Synchromesh, friction modified synchromesh and they also have a synthetic manual tranny fluid that is sometimes taken for a synchromesh.

I'm not sure about the regular or 'friction modified' synchromeshes but I think they are made by Pennzoil/QState/Havoline. It was originally developed by DC and GM got on the bandwagen.

The synthetic transmission fluid is I believe actually Castrol Syntorq LT (low temp?). It's pretty much only available exclusively thru GM in their bottles. It's about a 75W85. Nissan also offers a synthetic 75W85 tranny lube - don't know anything about it but sorta wonder if it's not also the same stuff rebottled. These are teh ONLY 75W85s I've found on teh market ANYWHERE so what are the odds?

None are API certified but I'd bet dollars to donuts they'd all warrant API GL-4.

Unless there's a specific reason to drop to a lower weight - mightt stick w/ the recommended weights like 75W90 or 80W90 or whatever - dont' recall off hand. If they recommend an 80W90 or 85W90 than a 75W90 would be no problem.

But if you want to try something at a lower weight perhaps for lighter shifting.. might try the 75W85 or MTL which is about 70W80 if I recall. But I'm in no position to recommend anything against the book!

If they are recommending a 90 wt Personally I think I'd drop MT90 in it at about 2 or 3K mi.

Hope that helps
Old 11-06-2003, 08:13 AM
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Re: torque spcifications?

Originally posted by jdl
(hijack alert!)
Anyone have a service manual that can quote the torque specs for various bolts? In keeping with this thread I'm interested in the drain and fill bolts for the MT6 transmission, differential, and the engine drain... -jd.
Can't help specifically but in the past most Japanese gear boxes use 1/2" square drive plugs. A large ratchet works perfectly. Some fill plugs are taken out w/ an open ended wrench or even an adjustable (Crescent) wrench will work fine (one of the few times I ever use such a wrench!).

I've never worried about torquing drain plugs back on to specific force - I have always just cranked them on good and snug so they don't leak. Most are NPT threaded.

Remember, ALWAYS remove or at least loosen the fill plug FIRST and consider just how you will get the new oil in BEFORE draining the existing oil (may need a pump...).
Old 11-06-2003, 10:10 AM
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Re: Re: torque spcifications?

Originally posted by pgtr
Can't help specifically but in the past most Japanese gear boxes use 1/2" square drive plugs. [...]
All good advice pgtr, thanks! Yeah, I've had loads of experience changing out the fluids on miatas over the years.

On a side note, I've found MT90 works better than MTL in my 99 miata (5-speed). The MTL left it feeling just a little crunchy (in So Cal). Now at 3100 miles on the rx8: MT90 this weekend.

Cheers,
-jd.

Oh, and still looking for torque specs from anyone that has 'em -- I find I way over-tighten w/o my T-wrench!
Old 11-06-2003, 10:47 AM
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I have to say I've had good luck w/ GL-4s in general for trannies speccing a standard lube and MT90 in particular. I think the MTL might only be worth considering for specific cases like trannies that spec 'lighter' fluids or something.

While it's not been quite so apparent for me on some American made trannies like old Muncies, on Japanese trannies, the MT90 has produced a very notable 'buttery smooth' shifting over other fills.

I've never tried the Amsoil GL-4 only fluid. (aka Marine lube - don't let that scare you - it's no different). The Amsoil dealers never want to sell it - they try to push pricier a GL4/5 combo so they keep losing my business. But their GL-4 is only about $20 by the gallon I think so it's actually pretty darn cheap too. Anyway some day I'd like to try it and see how it compares to MT90.

The other one I'll probably NEVER try is the Pennz/QState GL4 synth - it's liquid gold priced at $22+ per qt and only available by the case AFAIK! Rediculous. At least teh GM/Castrol Syntorq is available by the qt though equally pricey.

I for one would be curious to hear if ou notice any difference in shifting after teh MT90 goes in? What are the miles on your 8 as well? So post a followup...

thanks
Old 11-06-2003, 04:55 PM
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Originally posted by pgtr
[...]I for one would be curious to hear if ou notice any difference in shifting after teh MT90 goes in? What are the miles on your 8 as well? So post a followup...
I will. Currently at 3100 miles, the tranny and diff will get redline this weekend. I figure another week to see if I notice anything.

Cheers, -jd.

Edit: ok, I did the refill procedure and put up a page with pics and details.

Last edited by jdl; 11-19-2003 at 03:43 AM.
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