Subaru STi Syncro/Gear oil Conundrum!

[sw99]

In my 5MT, I use a blend of Wal-Mart ST 75w90 and Pennzoil Synchromesh. I'm at 213K and the shifts are better than ever. I was experiencing difficult [censored] also so I tried this. I would guesstimate I'm at 70% 75w90 and 30% PZ SM. Going on 1 year so far and still GTG. Shifts are A+...

 

[MolaKule]

So there you go Jconrad, a plethora of possible solutions to help shifting and maintain wear control.

Aren't you glad you stopped by?

 

[Thingfish]

All I was trying to do was give the box the protection Subaru wants, while adding just enough traction to the synchros for a well behaved STi box.
And it lasts for a very long time, especially on newer cars that are done breaking in and it's time to drain all the poopoo and stop further wear as much as possible.

If it's a box that likes to crunch, I would use 2 full MTF and 1.35 of FGR.

( 2.35 FGR and 2 MTF )

Remember to remove the small pan and clean the magnet! ( 6spd only only )

 

[Chris_N]

Wouldn't we want to use lubes that use roughly the same additvives when mixing, to make sure we get to the proper reactions when needed?

I once asked Amsoil about mixing MTF and MTG, and they told me not to do it, because they do not use the same EP/AW package. It can been seen looking at VOAs, where MTF appears to have more P and Zn, and MTG Boron and P.

Mixing both, you get kind of half the concentration of one EP package and half the of other. Would'nt that handicap the chemical reaction required during EP?

Knowing this, I'd try to find the gear lube that has the most similar package, but maybe it's not that important.

Also, since it's cold in Canada, I was more thinking about mixing MTG and Motul Gear 300 if deemed compatible. MTG has 13.9 cSt which is closer to the Subaru Extra-S and right in the xx-90 range.

Christian

 

[Pablo]

Mixing MTF and MTG are just fine. Amsoil has even stated to me that this is just fine. I can see the reluctance of mixing gear oil and MTF. They are indeed very different - BUT this does not mean they can't be mixed and used in a very specific MT.

 

[MolaKule]

Quote:
Wouldn't we want to use lubes that use roughly the same additvives when mixing, to make sure we get to the proper reactions when needed?

I once asked Amsoil about mixing MTF and MTG, and they told me not to do it, because they do not use the same EP/AW package. It can been seen looking at VOAs, where MTF appears to have more P and Zn, and MTG Boron and P.

Mixing both, you get kind of half the concentration of one EP package and half the of other. Would'nt that handicap the chemical reaction required during EP?


Both of the Amsoil manual transmission fluids have about the same Anti-Wear (AW) packages and friction modifiers, the only difference being viscosities.

By mixing a GL5 diffy gear lube, which has a Extreme Pressure EP additive, with a GL-4 manual transmission fluid, you get the friction modifier, the EP additive, and the AW additive.

By using about a 3:1 ratio, you get a 3 to 1 proportional mix.

 

[Chris_N]

Hi Pablo and Molakule,

Not to challenge you guys in any way, but here is what Amsoil Tech replied me Nov. 2011:

''Christian;

The additive system in the MTF is different than that used in the MTG and the two are not compatible with each other. Select one or the other only. As this is racing, I will not make a specific recommendation.''

I wanted to mix MTG and MTF to increase the viscosity a bit for my neon transmission, since it's working a bit harder than stock.


As I am saying, the VOA/UOAs tend to show they do not share the exact same additives.

I would not want ending with a too weak concentration of lets say a P-S based EP package, because of mixing and diluting it with another fluid with a Zn-P based AW.


I'll change the tranny fluid in my '11 STI soon, so this is higly interesting.

Thanks for the information and learning,

Christian

 

[Pablo]

I've had 60/40 MTG/MTF in my Volvo for 60K+ miles (since 100K or so). I might do a UOA at 200K or not. Amsoil tech goes by the book.

 

[Chris_N]

Hi Pablo,

Thanks for the feedback. I understand it can live that way. I had about the same ratio in my Accord for at least 100k km, but just because I poured my leftovers in it.

Because it doesn't fail doesn't mean it's the right mixture. The accord could probably have lived on soya oil FWIW

.

Still, I agree that mixing transmission fluid with GL-5 gear lube is probably ideal for Subarus. I'd just prefer finding the one that are most compatible.

I was thinking Amsoil MTG (13.9 KV100, 162 VI) with Motul Gear 300 (15.2 KV100, 222 VI). The end result is still 75w-90 weight.

Both seem to have Boron on top of Mg and Phosphorus.

What do you guys think?

 

[MolaKule]

Quote:
The additive system in the MTF is different than that used in the MTG and the two are not compatible with each other. Select one or the other only. As this is racing, I will not make a specific recommendation.


Sorry, I respectfully disagree with the Amsoil tech. In addition, if this is a racing application, I would also decline a recommendation unless I had a specific racing MTL. Just corporate CYA speak.

Quote:
Still, I agree that mixing transmission fluid with GL-5 gear lube is probably ideal for Subarus. I'd just prefer finding the one that are most compatible.

I was thinking Amsoil MTG (13.9 KV100, 162 VI) with Motul Gear 300 (15.2 KV100, 222 VI). The end result is still 75w-90 weight.


Sure, if you want to keep a viscosity close to a 75W90, then that mix will work.

According to the OP, the Motul is not the majic Elixar for smooth shifting.

 

[Chris_N]

Thanks for the reply.

Well, my STi is shifting well enough in summer with the OEM fluid.

It's only quite stiff to get in 1st or 2nd gears for the first 1/4 mile in cold weather.

THat's why I was thinking the Motul with the 222 VI, mixed with some MTG for the FMs would be the best for my condition.

I may just try it and report back eventually.

Both MTG and Gear 300 seem to have similar additives on paper, without knowing the S content.

Thanks,

Christian

 

[Zwalk]

Sooo...I've got a 05 STi an I'm grinding in 4th and a little bite in 5th, I've tried Motul 300 and Extra S and I am about to try lightweight shockproof mixed with the extra s...

What did you guys find as a verdict...

 

[Zwalk]

That is just what j have been seeing that people are Doing with my issue...I'm worried the synchro may be toast but I was hoping with proper lube I could avoid a 2100 dollar rebuild.

 

[buster]

Extra S is the way to go in a Subaru MT. Works great.

 

[MolaKule]

If anyone has a recent VOA of Subaru 75W90 Extra-S Gear & Transmission Fluid to verify the numbers, we can add this to our master list of MTL fluids.

 

[SilverGGA]

I have used Extra S since forever. Some has success with Mobil 1 Delvac 75w-90 if cold shifting is an issue.

 

[fredrik94087]

I just swapped in a 2015 sti transmission into my 2015 wrx and get similar notchiness as others have reported.

sometimes it wont go into reverse and I drop it in 2nd then it goes into reverse. Same for 1st gear.

I have motul 300 and will be switching to redline.

Thanks for the suggestions here.

If redline doesnt do it, I will try thr 3:1 gear oil and MT oil.

I will give redline at least a week to work.

Are you guys recommending removing the pan and cleaning the magnet? If so, why?

 

[fredrik94087]

folks here recommended redline 75w90ns. My installer was recommending redline lightweight shockproof. The redline tech said to not run shockproof in my transmission. A shop owner with an 800hp subaru is running shockproof for his sti transmission.

So...we did a 3:1 redline 75w90 and redline lightweight shockproof.

It allows for smoother gear shifts than straight motul. I wish I had a reference for straight redline 75w90ns.

the improvement is not night and day, and I still get blocked from reverse, but not as often. the block from 1st has not yet happened.

if the block from reverse goes away, I will definitely update, but I dont believe anything will change. I have had this cocktail for at least 4 days.