# What exactly does gear oil do?



## VwGtiDriver (Mar 10, 2015)

I get that gear oil lubricates the gears. But I have a clunk when shifting into reverse and a grind when downshifting into 3rd. I notice my gears are a little hard to shift into. Will adding some good gear oil help my issues?


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## ps2375 (Aug 13, 2003)

The correct gear oil could help, but the reverse clunk could be alleviated if you waited an extra second after you push in the clutch pedal before moving the gear lever. New gear lube might help the stiff shifting, and may or may not help with the grind on the downshift. That could be a worn synchro also, and gear lube generally won't help that. But, rev matching might.


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## jimbbski (Jun 3, 2007)

What kind of car do you have?
When was the last time the gear lube was changed?

Putting in fresh Synthetic gear lube may help, it can't hurt.

Just make sure that your trans calls for "gear lube" and not ATF. 
Many modern manual trans use ATF and not "gear lube" for lube.

The "grinding" you hear is the trans way of telling you that your synchronizers are wearing out. 
If you want to know what they look like and how they work go here:https://www.youtube.com/watch?v=MXsRfbOiBhE


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