Time to switch-out fluids and I'm considering Amsoil products based on the fact that the I started using Rotella T6 based on recommendations here and it's awesome.

Amsoil shows the following for the MSM transmission (not sure if items are listed in order of their recommendation/performance):


I've seen recommendations for the GL-4 75W90, but no discussion on the GL-5 80W90. Any experience with it, or technical reasons for not using it? Mazda spec says GL-4 or GL-5 are OK. Any reason to avoid the GL-5?

For the diff, Amsoil shows:

Again, seen recommendations for the SEVERE GEAR, but not discussion of using the 80W90. Any reasons why?

I have to admit, it would be nice to run the same fluid (80W90) in both locations.

Experience, recommendations, thoughts?

Thx.

 

I have the former of both in my car now.
Works great. You can see my thread with discussions on both from some smart people if you search.
Can't comment on the latter since neither I nor anyone I know ran it.

 

I used 75w90 in my Miata trans. it worked really well as far as gear oil goes.

Its not a "quiet" oil by any means, but the gears shifted well. I should mention that the noise could have been the 7lb flywheel and solid hub clutch resonating through the transmission too... just a lot of buzzing from the shifter at high RPM, but again the shifter worked wayyyy better than the oil that was in there... I think it was motomaster 75-90.


I also used a weird 75-90 and sae250 mixture for my diff being that I had a custom build OS Giken. That diff was SO quiet. Would use amsoil on everything again.


You can get a preferred customer card and buy direct on their website. Much cheaper than Canadian tire, but it will take a few days to come from their warehouse in Toronto. The customer card makes sense being that its like $6 or something and will save you more than that on your first purchase.

 

I believe Hustler has some old posts about why you need to use a GL-4 oil in the Mazda 6speed.

 

Yeah I remember that discussion. OP - do an advanced search on these fluids on here, there have definitely been some seriously awesome discussions on it in the past.

 

Thx. I shall do further searching.

 

I've always used the 75w-90, MTG in trans, SVG in diff per Savington's recommendations.

 

Found the threads you guys mentioned.

Conclusions:

- Everyone likes Amsoil MTG 75W90; Emilio likes it with some GM Friction Mod added-in
- Motorcraft Full Synth is well regarded with 6-speed (what I've been using), but no UOA data
- With respect to shifting feel, there has been direct comparo between MTG and Motorcraft.
- Hustler is on a crusade to ensure no one puts GL-5 in their gearbox despite the fact that the Mazda manuals say GL-5 is OK for my gearbox (2004 MSM)
- no one has tried the 80W90, which is GL-5

Did I miss anything?

 

I put MTG 75w90 in our MSM and it was the the ****, the bee's knees, solved world cancer, cured my IBS, and any other awesome thing you can possibly think of.

As an Amsoil dealer myself, i'm directly responsible for at least 100 Miata transmissions being filled with the MTG 75w90 at this point. Done 6 myself. 3 of which were replacing garbage Redline bullshit and every last one i replaced Redline with Amsoil resulted in the car's owner offering me fellatio.

 

Yep, pretty much sums it up.
Just cause a manuf says something is OK doesn't mean its a good idea. Just saying.

You should guinea pig the 80w90 gl5 and report back

 

GL-5 = renewed virginity

 

I should get my wife to try some!

 

You guys are the biggest bunch of border-line autistic fucktards on the interwebs.

Order & Monies sent to Savington.

 

in an effort to try and find 6 speed high load longevity in a bottle I am now trying

Amsoil SAE 250 Severe Gear GL-5.

seems to shift ok once it warms up a bit. It's thick. Hoping it actually works unlike Redline Heavy shock proof.

 

Isn't GL-5 not recommended for the Aisin 6-speeds because of yellow metal synchros being damaged by the sulfur additives in GL-5? At least that's why it's not recommended for the 5-speeds. Diff don't care.

Redline Heavy Shockproof is not recommended for any transmissions other than straight cut dog boxes. Their website says no synchro trannies. The stuff is basically a liquid carrier for the lubricating solids.

 

MTG FTW

 

Mix of old quotes there. A long while back we used the GM stuff with Redline. We switched to Amsoil MTG (no additives) for transmissions about 4 years ago. For Torsens, Amsoil SVG 75W90 GL-5. For OS Gikens, their proprietary OS250R soup.