Lgt grinds into 2nd at times

[Mintoneowner]

Hey there,

 

I was curious as to what fluid and it's.intervals for diffs and manual trans. I sometimes get a 2nd gear grind, hoping it's just low fluid/dirty fluid. The car has 85k.

 

Thank you

[Dishwasher]

30k miles on transmission and diff fluid changes, that's really at the latest.

[Max Capacity]

Check the fluid level before you do anything and report back to us.

 

There is a "cocktail of fluids" that will/may help the grinding. But it is a bandaid, not a repair.

[LuckyProfessional]

Is it a definite grind or just a vibration/whirring? I know every time I shift into 2nd below 3k rpm and 20mph I get a vibration on acceleration. Similar to what you're having or no? Does it happen regardless of rpm or speed?

[Max Capacity]

http://www.grimmspeed.com/1-transmission-cocktail-mix/

[bdfreetuna]

The question is... go with the cocktail or use Motul 300?

 

I'm about 8,000 miles into a transmission oil change with Lucas synthetic. Not completely unsatisfied but 2nd gear requires a bit of extra care.

 

Seems like either option would probably "solve" the issue.

[MilesA]

The question is... go with the cocktail or use Motul 300?

I would just go with the straight Motul 300. Sometimes, the transmission oil is just not a good match for the synchos and you get grinding. We used to get the real Extra-S that was a great match. Change every 30K.

[d22597]

I would do this first ^^^

 

I used the cocktail to bandaid my 6mt for a few years. It did work, but when I recently had the syncros replaced the trans shop warned me not to use again b/c it really gummed things up.

 

 

Sent from my iPhone using Tapatalk

[outahere]

There is also the "BAC5.2 Cocktail" of Motul Gear 300 and Lightweight Shockproof, at ratios of 1:3 to 1:1. For frigid temps, a 1:1 or 1:2 mix should work better.

 

http://legacygt.com/forums/showthread.php/best-transmission-differential-oil-200762p3.html

 

BAC5.2 wrote:

...As for Shockproof "eating synchros", that's a load of bollocks. I ran straight lightweight shockproof in my Forester for 100k, without any issues whatsoever. I've run it, and suggested it, for hundreds of Subarus without a single negative report. I've even torn down transmissions that have been running the Motul/Shockproof combo for a LONG time without any problems.

 

You should NOT use Synchromesh in a Subaru 5MT. Synchromesh is a fluid intended for gearboxes requiring GL-4 fluids. GL-4 fluids can't handle the shear loads seen in high offset hypoid gearsets (like our front differentials), and you'll see over time that fluid shears and wears the ring and pinion down to nothing in cars driven hard. I have a scar on my right index finger where a ring gear sliced through my glove.

 

Any GL4 fluid will cause this, not just Synchromesh. MT90, for example, will do the same thing. There was a small company who built kit race cars using the Subaru 5MT converted to FWD. They were running MT90, and were destroying front diffs after just a lap or two. They switched out to Motul/Shockproof and never had the issue again.

 

I've said for years, my preferred trans fluid setup is Motul and Lightweight Shockproof. It's what I recommend. As an alternative, I suggest Extra-S, Motul, or any other high quality synthetic. I don't recommend Royal Purple, Mobil 1, or Redline's 75W90NS, based on poor results. I am also a huge supporter of frequent fluid changes. I typically change my trans and rear diff fluid every 15-20k miles...