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How late is too late for a fluid change on a manual trans?
Ever since I got the car I’ve done pretty much everything maintenance wise, but haven’t yet touched the transmission. The car is sitting at 143k miles, I don’t know if it ever even had a transmission fluid change before. My friend told me since my car is high on miles it might be best to not change it at all since whatever’s in the fluid e.g. metal pieces/shavings is what’s holding it together. I’m now going through the infamous 5th gear grind, and in the mornings it’s pretty hard to get it into second sometimes without pulling really hard. Would really appreciate the input!
Ever since I got the car I’ve done pretty much everything maintenance wise, but haven’t yet touched the transmission. The car is sitting at 143k miles, I don’t know if it ever even had a transmission fluid change before. My friend told me since my car is high on miles it might be best to not change it at all since whatever’s in the fluid e.g. metal pieces/shavings is what’s holding it together. I’m now going through the infamous 5th gear grind, and in the mornings it’s pretty hard to get it into second sometimes without pulling really hard. Would really appreciate the input!
It's not too late. There IS the old wive's tale about the varnishes, sludge and other buildup of gunk basically making the transmission "take a set" and while there's some truth to that, a good lubricant change is NOT going to hurt anything in a manual transmission.
Now, we ARE talking 6MT manual gearbox, yes?
The old wive's tale holds a bit more truth on automatic transmissions where the clutches, gears, and other friction surfaces can "take a set", so to speak. But manual transmissions are largely just a box of gears and components (like synchros and such) to help the driver make it through the gears. In that case, a gear fluid change can only help - IF the transmission is still in good shape. Because your car is exhibiting issues already, a fluid change is likely useless as there are indicators that your synchros are already shot.
But to the basic question... NO, you're not going to hurt anything by changing the gear oil. But you're also not likely going to fix the 5th gear issue either. There is no liquid magic that will fix a dead/dying synchro.
But it is suggested trying a synthetic fluid such as Redline MT-85 (75W-85) which DOES provide better lubrication for the trans but again, won't fix a damaged synchro. In the meantime, you can make it last a bit longer with a bit of shifting finesse using double clutching and rev matching to ease the transition from 4-5 and particularly in 6-5 downshifts. Case in point: When I bought my '03 (with notorious reputation for 3rd gear gronk), I switched to MT-85 and just nursed shifts into that gear and it went 10+ years without breaking apart entirely. However, with the occasional brain fart and "old guy lack of physical coordination" under high speed pressure to grab 3rd, I still gronk it during heel/toe maneuvers a couple times a year.
You didn't mention the year of the car which can tell you what transmission you have in the car (CD001 to CD009) and guessing it's a pre-CD009 which tend to be the models that break synchros. Good news is that a NEW transmission from Nissan (CD00A - newest version of the venerable CD009) is "only" a couple of grand. I say "only" because that makes it well worth it as compared to fixing an older unit. Still expensive but much cheaper than replacing a newer, e-controlled CVT or other automatic trans.
It's not too late. There IS the old wive's tale about the varnishes, sludge and other buildup of gunk basically making the transmission "take a set" and while there's some truth to that, a good lubricant change is NOT going to hurt anything in a manual transmission.
Now, we ARE talking 6MT manual gearbox, yes?
The old wive's tale holds a bit more truth on automatic transmissions where the clutches, gears, and other friction surfaces can "take a set", so to speak. But manual transmissions are largely just a box of gears and components (like synchros and such) to help the driver make it through the gears. In that case, a gear fluid change can only help - IF the transmission is still in good shape. Because your car is exhibiting issues already, a fluid change is likely useless as there are indicators that your synchros are already shot.
But to the basic question... NO, you're not going to hurt anything by changing the gear oil. But you're also not likely going to fix the 5th gear issue either. There is no liquid magic that will fix a dead/dying synchro.
But it is suggested trying a synthetic fluid such as Redline MT-85 (75W-85) which DOES provide better lubrication for the trans but again, won't fix a damaged synchro. In the meantime, you can make it last a bit longer with a bit of shifting finesse using double clutching and rev matching to ease the transition from 4-5 and particularly in 6-5 downshifts. Case in point: When I bought my '03 (with notorious reputation for 3rd gear gronk), I switched to MT-85 and just nursed shifts into that gear and it went 10+ years without breaking apart entirely. However, with the occasional brain fart and "old guy lack of physical coordination" under high speed pressure to grab 3rd, I still gronk it during heel/toe maneuvers a couple times a year.
You didn't mention the year of the car which can tell you what transmission you have in the car (CD001 to CD009) and guessing it's a pre-CD009 which tend to be the models that break synchros. Good news is that a NEW transmission from Nissan (CD00A - newest version of the venerable CD009) is "only" a couple of grand. I say "only" because that makes it well worth it as compared to fixing an older unit. Still expensive but much cheaper than replacing a newer, e-controlled CVT or other automatic trans.
+1 for the reasons above. MT-85 will only help IMO, note that our 6MT synchros tend to be a little tempermental when the fluid is still cold. Using methods/techniques that Mic described helps until operating temps are reached. If synchro damage is present, then you just have to live with it or replace the trans. It's unusual for an 06 w/CD009 to have 5th gear issues.
You may also want to check your shifter guide plate adjustment if that's ever been taken apart for clutch work or shifter mods. Sometimes these are not put back together correctly and will lead to difficult shifting issues for 5th and 6th gear. I experienced this problem on my Z after purchasing. Nissan had Warranty replaced the transmission (previous owner) and their tech never re-adjusted the shifter guide plate correctly. See screencaps of FSM procedure.
Cheers!
-Icer
good information here guys. Thanks for sharing. I have an 04 MT and thankfully i havent had any issues with it yet (knock on wood). Ive read that theres been people with the early MTs that have never had any issues with them well over 100k miles.... hoping ill never have to replace my transmission.
+1 for the reasons above. MT-85 will only help IMO, note that our 6MT synchros tend to be a little tempermental when the fluid is still cold. Using methods/techniques that Mic described helps until operating temps are reached. If synchro damage is present, then you just have to live with it or replace the trans. It's unusual for an 06 w/CD009 to have 5th gear issues.
You may also want to check your shifter guide plate adjustment if that's ever been taken apart for clutch work or shifter mods. Sometimes these are not put back together correctly and will lead to difficult shifting issues for 5th and 6th gear. I experienced this problem on my Z after purchasing. Nissan had Warranty replaced the transmission (previous owner) and their tech never re-adjusted the shifter guide plate correctly. See screencaps of FSM procedure.
Cheers!
-Icer
Thanks for the info, you made my day <3
Edit: It helps me a lot.
Last edited by LaraStevenson; 06-06-2024 at 01:40 AM.
05-03-2024, 06:03 AM
How late is too late for a fluid change on a manual trans?
