Redline MTL transmission oil

[Sam Buchanan]

After getting the transmission leaks fixed I put GL-5 oil back in it. No, that is not old-school GL-1 but the bottle said "recommended for manual transmissions". However, I've had a persistent crunchy 2nd gear shift going either up or down until the transmission got hot, then 2nd would shift smoothly. I even resurrected my long-forgotten double-clutch technique. 

 

In the course of researching alternate oil I read up on Redline MT90. It is less "slippery" which promotes good synchronizer operation but I saw where it is recommended for high performance use with a hot transmission. For street use Redline recommends their MTL (GL-4) which is supposed to work even when cold. It has very low sulfer content so it plays nicely with brass synchronizers.

 

The "crunchies" are gone, even with a cold transmission. Second slides into gear very smoothly going up or down. The only downside to the Redline is the price, a little precious at nearly $20/qt. But I consider it a fine value to get a smooth-shifting transmission. I haven't used GL-1, it may work as well, but wanted to let folks know the MTL seems to be a good option for addressing notchy shifts.

 

 

Edited October 17, 2019 by Sam Buchanan

[Adam H P15 D30]

Exact same results when I changed mine out from the NAPA GL1 to the MT 90. Since you will probably never have to change it again, price is worth it....

[Old CWO]

Redline MTL/MTG are awesome but as you say, the price can be a bummer for some.  Pennzoil Synchromesh is a great option at only $10 a QT if price is an issue.

[Loren]

Redline has for years made gear lubes that performed.

We used them in off road racing in a car that had a notoriously weak transmission and never had a failure.

One thing I’ve learned over the years is that thicker lube isn’t always better. A thinner lube can run cooler and if temperature is killing your bearings as in our case, thinner is better.

The factory recognized this and went from 90 wt to 75 wt which is like water, then settled on 30 wt motor oil.

I have always tried to drain a transmission and replace the lube with ATF before pulling it for repair.

A few hundred miles with ATF in them makes the rebuild process so much easier because when you take them apart the inside is razor clean. I haven’t figured out how to clean the outside as easily yet.

Redline lube gets my endorsement whole heartedly.

I know the Overdrive gurus are fixated on GL-1, but my experience with ball and roller bearings, brass syncros and sprag clutch freewheeling makes me think there’s a Redline product that will work fine.

[lepic56]

hi

is the choise of AMSOIL SEVERE GEAR® Synthetic Extreme Pressure (EP) Gear Lube 75w-90 for the transmission is too much weight???? should I used sae 30 oil,,   1951 dodge crusader (coronet) 

[Sam Buchanan]

1 hour ago, Loren said:

Redline has for years made gear lubes that performed.

We used them in off road racing in a car that had a notoriously weak transmission and never had a failure.

One thing I’ve learned over the years is that thicker lube isn’t always better. A thinner lube can run cooler and if temperature is killing your bearings as in our case, thinner is better.

The factory recognized this and went from 90 wt to 75 wt which is like water, then settled on 30 wt motor oil.

I have always tried to drain a transmission and replace the lube with ATF before pulling it for repair.

A few hundred miles with ATF in them makes the rebuild process so much easier because when you take them apart the inside is razor clean. I haven’t figured out how to clean the outside as easily yet.

Redline lube gets my endorsement whole heartedly.

I know the Overdrive gurus are fixated on GL-1, but my experience with ball and roller bearings, brass syncros and sprag clutch freewheeling makes me think there’s a Redline product that will work fine.

 

MT-90 is rated as 75W90 and MTL is 75W80. I suspect the lower viscosity is why MTL is recommended for street use where transmissions are often not up to high temps.

 

Thank you for the datapoint....sounds like the MTL is a long-term solution for my car. 

Edited October 18, 2019 by Sam Buchanan