Just wondering which 75W-90 gear oil everyone running AMSOIL is using?
I see that AMSOIL has both "Synthetic Gear" and "Severe Gear" lubes in the weight of 75W-90.

I've been running Redline for several months now. Synchro performance (when tranny is warm) is very smooth. However, shifting when the tranny is cold isn't so good...occaisionally grinds from 1st->2nd, but always grinds from 2nd->3rd. And yes...I fully depress the clutch when shifting, and I never get the grinding after driving about 5 minutes.

I never had the grinding with the oem fluid (even when 10 or 15 degrees last winter). However, oem fluid synchro performance was horrible (as most would agree I think).

I was curiuos if those running AMSOIL had similar issues with cold shifts. I appreciate the feedback, as I'm trying to determine if its worth changing to AMSOIL.

Thanks.

 

I have the same issue with my tc. First 5 minutes always sticks-grinds a little between 1st and 2nd, then 2nd to 3rd. I have 36000 on mine and recently had the trans fluid changed (they used the standard fluid that came with car), but I notice the sticking is even more pronounced now. I always have the clutch fully depressed when shifting. I'm not sure what to do to resolve.

 

I have redline... You shouldn't be grinding at all... You might have fubared synchros. I'm at 50K mi and still shift hard and aggressively everyday. However I double clutch all my downshifts so not to wear the synchros. My tranny still shifts like new and never grinds.

My first MT car had synchro problems (because of my aggressive shifting). Once I had the synchros replaced, I learned to double clutch. Every car since then has been grind and problem free.

 

I just can't logically blame it soley on sychros quite yet...since it's not repeatable (cold vs warm). Honestly, I couldn't even replicate the issue at the dealer unless I left the car sitting overnight at the dealership lot.

I guess the simplest way to check would be to switch back to oem fluid (or AMSOIL) and see if the grinding continues.

I gathered some kinematic viscosity data below to check if anything stands out. Note that the Redline MT-90 has the lowest viscosity @40C...thus its a bit more "runny" at 40C than most of the other gear oils below. Makes me wonder if maybe the MT-90 tends to drip off the gears & synchros more than other oils after the car sits for several hours.

Of course, this is somewhat contradicting with needing to "warm up" the MT-90. I say this because its already more "runny" cold than probably the oem fluid (I'm guessing Toyota uses something close to Mobil 1). But maybe the grinding is only caused by oil draining off the gears/synchros after sitting...driving would obviously act to properly reoil all the gears/sychros.

Mobil1 Syn 75W-90:
106 cST@40C
15.2 cST@100C

Redline MT-90:
90 cST@40C
15.6 cST@100C

Amsoil Long Life Syn 75W-90:
122.6 cST@40C
15.9 cST@100C

Amsoil Severe Gear Syn 75W-90:
108.8 cST@40C
16.4 cST@100C

 

Is it normal to have synchro problems when you don't shift aggressively with only 36000 miles? I've been driving manual a long time and never had the issue before. Does anyone have any suggestions? Any help is appreciated. I'm not real technical when it comes to cars, so I apologize in advance for my posts. Should I be posting this in a different thread?

 

I switched to Redline last week and have noticed since that it is pretty notchy when cold. As soon as it warms up though, it's good to go. I had the same issue with the oem fluid though, but I was hoping to fix it. Doesn't really matter though since I don't shift real aggressively when the car is cold anyway.

 

I've had Amsoil severe gear 75w-90 in since last oct. Cold shifting was improved over OEM fluid. I don't really have a reference to redline though.