I recently purchased a 2010 Forester with 95K miles and a manual transmission.  The fourth gear would grind a bit when shifting fast, and I would have to make sure that the shifter was pulled hard all the way back to get it into gear.  If I didn't the gear wouldn't engage and the gear would grind like it was sitting on top of the input shaft. I changed the fluid and it was black coming out.  I put in 3 quarts Redline lightweight Shockproof and the rest Motul 300 75w-90 and it got rid of the grind.  I do still have to really make sure 4th gear is engaged though. Could this be a worn shift linkage or bushing to replace that will tighten up the spacing or slack in shifting?

this is of interest to me too all my gears work but its kinda hard to get them into gear you have to go step by step between gears. i dont know if this is normal or its meant to drive slowly, which it does well enough.

this is of interest to me too all my gears work but its kinda hard to get them into gear you have to go step by step between gears. i dont know if this is normal or its meant to drive slowly, which it does well enough.

 What lube is in the trans now? Synthetics don't work well for many people. I liked the RL Lightweight SP I used in the past. And the Amsoil Severe gear in there now is OK (both feel better to me than the Subaru stuff - but I haven't felt the Amsoil in the Summer yet.) Motul has lots of fans, it's also pricey though.

 

no fluid will repair a broken trans, but some let the synchros work better if you have clashing or 'notchy' shifting.

 

Some folks are praising the Walmart synth-BLEND stuff and it's 1/2 - 1/3  the price of most lubes reported to work well; http://legacygt.com/forums/showthread.php/experimenting-wally-world-supertech-75w-90-88763.html

Edited December 18, 20169 yr by 1 Lucky Texan

You'll probably end up having to split the trans.

Either the sliders on the 4th gear shift fork are worn from someone resting their hand on the shifter, or the input shaft main bearing (directly behind 4th gear) is bad and is letting the input shaft walk back when you try to engage 4th.

Or could just be a chewed up 4th synchro either from someone not knowing how to downshift, or forcing it out of gear when there's load on the synchro ring.

Lots of options, none are repairable with fancy fluid.

Whenever I see fluid come out black I change it with the cheap Walmart 80-90 fluid and run that for a week or so then change it again.

Edited December 18, 20169 yr by Fairtax4me

Damn. Wish I had thought about a thorough flush with cheap stuff before I dropped 60 bucks worth of good stuff into it haha. I did that with my old 99 suby and it had a great effect on it. I'm thinking it's a bent shift fork or something and not syncros. As the fluid had moved around I dont get the grind from a fast shift anymore. It's doable as is and definitely not worth splitting the trans.

thanks good info

could be something else but 99% chance it's just the synchros from dropping 5->4 a lot. My baja's the same way.