Red Line(50204) SAE 75W80 API GL-4 Manual Transmission and Transaxle Lubricant - 1 Quart (Pack of 2)

This car I own has not had trans fluid changed for long time . After installing oil , noticed smoother shifting with great ease . This is the best oil for the right application .

Have used this gear oil in a 2nd (BL) and 3rd gen (BM) Mazda 3 with the 2.0L Skyactiv-G engine. Both were 6 speed manual (obviously) and this gear oil makes shifting silky smooth. It's good stuff.

Pretty smooth shifts from 1st to 2nd from what i noticed between the redline and honda mtf. Pretty good stuff

The 2006-2008 Civic Si's have a 2nd or 3rd gear grind, for me it was happening everytime at high RPM's. So I got a Hybrid Racing CMC and Slave Cylinder kit, Acuity Shifter Bushings, and new transmission fluid. I have already used Honda OEM transmission fluid before and it would still grind.So I got this fluid instead just to try out and it actually does help a little bit. If I recall correctly this has different operating temperatures than the Honda OEM fluid and reacts differently to different synchros at high RPM's. For me, it just improved the overall shifting feel, everything feels a lot more crisp and tactile when going into gear which is very nice.This isn't a definite fix to gear grinds, I highly recommend getting the Hybrid Racing CMC and Slave Cylinder kit since with the new slave and clutch line, it makes installing a lot easier and it aids in the transmission responsiveness as well. Hondata will help with rev hang so you can really bang gears, Acuity and Hybrid Racing shifter cables/bushings help a lot with shifting feel.All of this and a possible transmission rebuild/repair will definitely fix the transmission problems and you'll be banging gears all day. I've only been running this fluid and the hybrid racing kit and the grinding has basically fixed itself. I grinded 2nd like once trying to powershift but it still went into gear and I chirped 2nd, but that's due to my 2nd synchro being damaged, I've literally grinded that thing over a hundred times.Motor mounts will also help a lot with reducing drivetrain shock (aka how your gears grind half the time) as well. But this fluid is a minor band-aid solution and I'm not totally sure on the reliability aspects in certain ambient/operating temperatures and how they would react but it should be all fine and safe to use.Overall, it improves shifting feel and can be a band-aid solution for gear grinds.

This is highly recommended within the automotive community. Works great as expected.