Syncromesh MT and synthetic gear oil?

[Jimmy9190]

I am becoming schooled on manual transmission and gear oils. Up until now I have used factory Mopar lube in the NV3500 and in the rear differential on my Dakota. I am finding out that Pennzoil Synchromesh is the same as the mysterious Mopar Manual Transmission Lubricant for less than half the price of the Mopar fluid, and the rear differential can accept any brand of 75w-90 GL 5 gear oil. I can buy Valvoline 75w-90 conventional gear oil for $6.50 a quart instead of paying $15 per quart for Mopar Synthetic 75w-90.

Is the Pennzoil Synchromesh a quality lube or should I just continue to bite the financial bullet and drive across town to buy the Mopar MT lube? My current fill of Mopar MT lube has about 30K on it and I am beginning to get a fair amount of ratchety/notchy/noisy and grinding shifting now. My truck has 91K on the odometer now.

Is there any real advantage to using synthetic gear oil in the differential? Would I get just as good of performance from conventional as long as I changed it out more often? Valvoline synthetic gear oil is about $12 a quart.

I don't know much at all about gear oil or transmission fluids. Any help on this is very much appreciated.

 

[JohnBrowning]

Well Amsoil,Redline and Royal Purple all make a Synchromesh product that is better then OEM and cost a little less and all are synthetic. I like Redline but a lot of guys on this site are saying some good things about Amsoils MTL as well.

Now for the rear end it is not going to matter much in Florida other then the length of time you can run the gear oil between conventional and synthetic. If you go with synthetic M1 is usualy the best deal around at Walmart or Autozone or Advanced autoparts etc..... for a synthetic. Schaeffer's should have plenty of distributors in Florida and they make some great GL5 gear oils both conventional and synthetic.If you only going to use localy available gear oils then definately stick with only name brand products when you start looking at conventional and synthetic gear lubes stay away from store brands. Rotella,Delo,Delvac,Mobil,Castrol,Schaffers,Amsoil,Redline,Wolfshead,Havoline,Texaco all make good gear lubes.

 

[MolaKule]

Pennzoil Synchromesh is a good partial synthetic fluid.

Here is my short tutorial:

Quote:
GL4 does NOT refers to any specific viscosity, but it refers to a level of AW/EP protection for the gearing and bearings in a transmission.

A GL4 Manual Transmission Lubricant (MTL) can be any viscosity from 7.0 c`St (ATF equivalent viscosity) to a 75W90 type viscosity, and contains special friction modification additives for synchro engagement.

A synchromensh fluid usually refers to a specialized fluid that contains special friction modification additives for transmissions that use mechanical synchronizer assemblies; those synchronizer assemblies amy be made of carbon fiber composites, sintered metal, brass/bronze, or steel-steel materials.

Current MTL GL4 viscosites are:

1. ATF Series - Type; 6.5 to 8.5 cSt (Equivalent ATF viscosity; Note: ATF additive package is weak compared to most GL 4's)
2. Synchromesh Series -Type; 9.3 - 9.5 cSt (such as Texaco's MTL, Pennzoil's Synchromesh, GM and Chrysler's Synchromesh, Amsoils MTF)
3. 75W85 Series-Type; 9.8 to 11.5 cSt ( Redline's MTL, RP's Synchromax LT, Nissan's MTL, Honda MTL, Castrol Syntorq LT)
4. 75W90 Series-Type; 12.8 to 14.5 cSt (Amsoil's MTG, Redline's MT-90).



It is my view that one should never use a differential fluid in a manual transmission.

I would also try one of the fluids in item 3. to see how it shifts.

 

[Jimmy9190]

I certainly appreciate the info here. I'll likely get the Pennzoil Synchromesh for the transmission and the Valvoline conventional gear oil for the differential. On the Pennzoil website it says the Synchromesh is the equivalent of the Mopar MTL part number, so it should do the job OK.

What started this whole ordeal is last year I paid a transmission shop to drain and refill the MTL for me. That guy put in a synchromesh MTL that was very obviously the wrong lube. The transmission felt like it was full of mud and was very difficult to shift between gears. And it didn't improve as I drove either. So I bought the Mopar fluid at the dealer and changed it out myself. I didn't have any problems with the transmission after that.

As for the rear end gear lube, I'd like to save money by using Valvoline or any other good brand. The Valvoline is the only name brand I can find around here in 75w-90. That suits me fine anyway, I have been using Valvoline for years now and I know it is a superior quality oil. I'll use conventional and change it on an earlier schedule from now on. Mopar says in the owner's manual to change the diff fluid every 12K on the severe service maintenance schedule. I always thought it could easily go 30K.

Thanks very much for your help on this.

 

[aquariuscsm]

Originally Posted By: Jimmy9190
I can buy Valvoline 75w-90 conventional gear oil for $6.50 a quart. Valvoline synthetic gear oil is about $12 a quart.


That seems pretty pricey for the Valvoline products. When I bought the Valvoline conventional it was only $3.99 a quart. If you want an over the counter synth,Mobil 1 75W90 is only about $7 a quart and it came in 2nd in the Amsoil White Paper. Maybe it`s a bit more pricey where you live.

 

[Jimmy9190]

Napa is the only place around here I have been able to find 75w-90. Walmart sells some off-brand gear lube for 3 or 4 bucks but I won't use it in my truck.

 

[JohnBrowning]

I would never take a dino gear lube further then 24,000 miles or 24 months wich ever comes first! 30K is pushing your luck with a dino gear lube.Now most synthetics are good for 50K miles.Do you have a K-Mart or a truck stop or a garage near by. Heck I would see if I could not find a Schaeffers distributor you could easily get a better product then Valvoline for the same money that NAPA wants. Valvoline is a decent product it is not a supior product. Really if you can find Schaeffers,Delo,Rotella or the like at some place that services heavy equipment or tractors and such you are going to be further ahead inthe long run.

 

[Jimmy9190]

Well I found the Valvoline conventional gear oil for the differential at AutoZone. $4.99 a quart. I live in a little town in rural Florida and it was hard to find any other brand of gear oil that I could trust. For some reason it was hard to find 75W-90 too. A lot of places had 80w gear oil though. I wanted the sealant to have plenty of time to cure before driving my truck again so I went ahead and did the job tonight except for adding the new oil. Will do that tomorrow. I'll change the differential oil at 12K like the manual and many others here and on other forums have suggested.

My Haynes Book says to change the transmission fluid at 48K or 4 years. My Dodge owner's manual and My Dodge Dakota Service Manual say it does not need changing in normal service. The Dodge FSM says to use the Mopar Lube if the lube is ever changed though. Hard to know what or whom to believe. It has about 30K on it now but I will change it too next week when I change my engine oil again. I think after reading online I'll just get the mysterious Mopar Manual Transmission oil. I keep reading online how it has the correct amount of moly in it that you don't find in aftermarket brands. I hope that it will help the rough shifting I have had lately. If the transmission is in anywhere near as good of shape as the rear end was, I should have no worries. The rear end gears all looked great, just like new with very little evidence of wear. The oil that came out was a little burnt though.

Anyone who has any input on the Pennzoil Synchromesh as opposed to the expensive dealer MT oil, I am all ears. As always thanks everybody for the help here.

 

[MolaKule]

Quote:
I keep reading online how it has the correct amount of moly in it that you don't find in aftermarket brands. I hope that it will help the rough shifting I have had lately. If the transmission is in anywhere near as good of shape as the rear end was, I should have no worries. The rear end gears all looked great, just like new with very little evidence of wear. The oil that came out was a little burnt though.


I always caution against using an mtl with moly in it, as it interferes with the friction modifier for synchro operation.

As I stated previously, also try the oils listed in item 3 of the list I posted if your shifting with Pennzoil Synchromesh isn't what you expect. There is no majic wand and you sometimes have to experiment with different fluids to find out what works best.

Differential lubes with moly are ok.

It's your vehicle and pocketbook.

 

[Greaser]

I have the same transmission in my Jeep.Have used them all and like the Amsoil MTF the best.

 

[Greaser]

http://www.amsoil.com/storefront/mtf.aspx

 

[Pablo]

Thanks. Please use this link to direct your sale to Pablo:

Amsoil MTF