Kendog 170
Let the boy go !
I read that too. That's why my Ragtop just has 75w-90 now.
What fluid for a 4-speed trans?
- Thread starter halfafish
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I read that too. That's why my Ragtop just has 75w-90 now.
MOPAROFFICIAL
If it has tits, it's a liability.
I'd like to say that when I hurt some synchros ..that it was one of two things...switching to 90w... it the non performance pedal set and very quick shifts with it... but eventually it started grinding here n there and then it didnt slide right into gear, it need more force...you can feel the engagement as where you didnt before. Been 10 yrs like that. ..now I have a kit and will change the synchros and input bearing.
Look at the synchros and if they have a powdered look on the surface (like an aluminum waterpump) that's the hypoid additive. Use as thick a weight engine oil as makes the shift quality where you like it, atf, a mix, or GL3. Don't use GL5.
rustycowll69
Well-Known Member
Before you condemn the synchros and the lube. I would make sure you're getting full clutch departure. I've pealed a couple of bell crank arms off of the z-bar, trying to throw fast shifts at the dragstrip. Sometimes the bell crank arms can twist and bend, too, which detracts from efficient t/o bearing travel.
I've looked over the spec sheet for the Pennzoil Synchromesh, and I think it could probably be labeled as a SAE 80 GL-4. Putting that on the label, however, might cause people to use it in an application other than it's intended use of a passenger car and light truck manual transmission fluid.
GL-5 has a higher level of sulfur and phosphorus compounds, which can be corrosive to yellow metals like brass synchros. So unless actually spec'd for a certain trans, GL-5 is best avoided.
I used to sell a good deal of the Synchromesh, and before that lots of Pennzoil GL-4 intended for manual transmissions. Funny how the GL-4 oil was discontinued shortly after Synchromesh came out. It was never called a direct replacement, but...
GL-5 has a higher level of sulfur and phosphorus compounds, which can be corrosive to yellow metals like brass synchros. So unless actually spec'd for a certain trans, GL-5 is best avoided.
I used to sell a good deal of the Synchromesh, and before that lots of Pennzoil GL-4 intended for manual transmissions. Funny how the GL-4 oil was discontinued shortly after Synchromesh came out. It was never called a direct replacement, but...
harvenator
A fish called Wanda
It actually calls for GL4 in factory manual. The brass synchros dont wear with that particular oil. Just drained the 140 out to put in 90. The 140 was hard to shift until it got warmed up.
I would say pennzoil synchromesh. I’ve ran that before in the A833 and I liked it.
Yep. Me too.
Yes, you may get 100 different answers, but the fact is, the factory service manual only mentions a few.
What Viscosity or Weight is the Synchromesh?
At 100°C, claimed viscosity is 9.08 cSt, which puts it solidly in the range for an SAE 80W gear oil. At 40°C, viscosity is 41.6 cSt, equivalent to an SAE 75W gear oil. So, calling it a 75W-80W would be accurate.
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harvenator
A fish called Wanda
If you really want to know what oil to run call Brewer's. They're the experts.
Sawdust and pee it IS!!!!
They sell a mineral base Sta-Lube 85W-90 GL-4 and a full synthetic Red Line 75W-90 GL-4. Either will work well, but if using the synthetic may need you to have the later synchronizers with the oil bleeds.
I guess by selling those products, they have Brewer's endorsement.
Time marches on. Products are updated as specs become obsolete. There used to be six gear lube classifications, GL1 through 6. Now only 4 & 5 are currently specified. Case in point, try finding any of those listed in your service manual. Straight 80, 90 or 140 really don't exist anymore as most are multigrades. Also, that Dexron specced hasn't existed in that form since the '70s (probably). So, do the best you can with what's available.
A little light reading may help.
API Gear Oil Specifications - oilspecifications.org
harvenator
A fish called Wanda
harvenator
A fish called Wanda
Ya gotta understand, when they write the manuals, it's for what's available at the time.
Hope that the OP's head hasn't exploded by now. Some people just can't loose. Use what ever you want to use, it will be fine, but not with some people. For me, time to hit the UNWATCH THREAD BUTTON.
No one is trying to win anything, just contribute the best way we know how. You followed the golden rule, which is to go to the factory service manual. I lent my knowledge and experience from 32 years in the lubes business to update your contribution. I'm sorry if you felt otherwise. It's all good my friend.
scatpackbee
Well-Known Member
Redline MT-90 in mine.
Synthetic 75W90 GL4 rated.
Shifts amazing.
Synthetic 75W90 GL4 rated.
Shifts amazing.
chrgdrt
Well-Known Member
Had Liberty go through my trans due to a lock up in 1st gear, they recommend Staylube 24239. Haven’t put the trans back in yet so I can’t report on shift quality yet.
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oldpunko77
72 Dusta
Interesting topic so I have one question how many bottles to put in?
autopar3000
Well-Known Member
Take this comment for what it's worth, since I have an automatic in my Dodge... but my other hobby car is a an 85 Celica Supra with a manual transmission. The general consensus in 80's Supra circles is exactly what @scatpackbee said: Red Line MT-90. I put the MT-90 in the Supra and it's not a little better, it's WAY better.
From the Red Line website at MT-90 75W90 GL-4 Gear Oil
From the Red Line website at MT-90 75W90 GL-4 Gear Oil
- 75W90 GL-4 gear oil (similar to SAE 5W40/10W40 engine oil viscosity)
- Popular in Nissan, Mazda, Mitsubishi, VW/Audi, Lotus Elise/Exige, Toyota, Mendeola transmissions and Atlas transfer cases for Off Road
- Offers quicker shifts, perfect synchronizer coefficient of friction
- Safe for brass synchros, as it lacks the reactive sulfurs found in most GL-5 oils that cause damage
- High performance gear protection and longer synchro life
- Eliminates notchy shifting, even when cold
- Satisfies the gear oil viscosity requirements of 75W90, 80W90, 90 and motor oil viscosities of SAE 40, 10W40 and 15W40
- Recommended for GL-1, GL-3 and GL-4 applications, as well as where most special synchromesh fluids are specified
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