[Farmer]

The car in question is a 2012 Cruze 1.4L Manual Transmission

- I ran stock transmission fluid to 50,000 miles - No problems; avg 40-50mpg on fill-ups
- Flushed and switched to Amsoil Synchromesh (proactive maintenance) from 50,000 miles to 82,000 miles; avg 35-38 mpg on fill-ups

- 0-50,000 I was very light on the throttle and mostly highway mileage ; 50,000 - 82,000 miles was mostly city driving / moderately aggressive driving
- The reason for change in driving style is I started using my Cruze to UBER.

- @ 82,000 miles, the transmission started to grind in all gears and became more noticeable the higher the rpms get. Very noticeable sound but no driveability issues.
- Flushed and added new transmission fluid (Pennzoil Synchromesh) @ 82,000 miles

- Transmission no longer grinds in gear after new fluid added. Problem seems to be fixed.

My question is: Did 30,000-35,000 miles of city/moderately aggressive driving kill my Amsoil Synchromesh transmission fluid? Is that how long this fluid typically last? The Amsoil Synchromesh was in the car about 8 months.

 

[obermd]

I wonder if it's time to change your clutch.

 

[Robby]

Odds are the clutch is OK since the fluid change seems to have resolved the issue.

Manual trans fluid is a strange product.......it has to lubricate but at the same time not be so slick as to prevent the syncronizer rings from stopping rotation to allow a clean shift......so it is a combination of lubricants and friction modifiers.

It stands to reason that the modifiers can lose their effectiveness and I suspect this is the case here. Manual transmissions are brutal on the lubricants because a tremendous amount of 'shearing' occurs at the gear teeth.

I have always used a 25k service interval on my manuals and have never had grinding (beyond the self induced, WOOPS grind....darnit!) however, I can't directly comment on front drive manuals. My handshakers are all rwd.

With that in mind though, front drive manuals are at a bit of a disadvantage because their fluid also must lubricate the final drive...... rwd manual fluid only has the trans to deal with and that additional gearset may be just enough to speed up the lubricant degradation.

Maybe a 25k service interval, regardless of fluid type/brand, might be a good idea for all the fwd manuals.

Rob

 

[BowtieGuy]

From the Facebook Cruzetalk page, there was a past discussion on the Amsoil Synchromesh. Other users with hard driving report it begins to lose its effectiveness around 15k-25k miles. If the Pennzoil Synchromesh doesn't last, you may want to give the Amsoil 75W-90 MTF a try. I will be going with that in the near future.

 

[jblackburn]

I was never impressed with the Synchromesh - I still ground gears. The 75-90 did the trick for me and continues to do so about 20k later.