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Im looking to switch from my Mobil syn 50w to a redline product. I do not like the way it shifts. its too slow and grinds when cold. It never use to do this. My problem is I cant decide between the MT90 75W90, MT85 75W85, or the MTL 70w80 GL4 oils. From what I read the G56 requires 75-90 from Mercedes, But redline specs the MT85 for dodge truck and NV4500 trans and the MTL for the NV5600 or synchomesh applications. Any experience or info is helpful thanks
2004.5 Dodge 2500 QC 2WD short bed Jeff Garmon built 48RE trans, II SPS62, Fass 95, Smarty S06 POD, MBRP exhaust
2007 Dodge 2500 QC 4X4 short bed, G56 6spd, MBRP exhaust otherwise leaving this one mostly stock
never did this until after I switched to the 50w oil. I have the clutch in the truck with atf and it shifted just fine. I want something a little thinner. I have heard good things about redline and want to give it a try
Gear lube is not just about viscosity. Lube base stock is critical in heavily loaded transmission. Reason Mercedes spec'd a synthetic base stock lube for the G56 in MD real truck apps. read the whole Mercedes spec, it's in German but easily translated.
Vis @ 40°C and Brookstone are indicative of cold startup viscosity
Vis @ 100°C, cSt is indicative of running at spec temp conditions viscosity.
Higher viscosity lubes provide more film protection between the meshed gears and between bearing components.
It's a tradeoff between shift quality from lower viscosity and transmission protection/long life.
Brookfield Viscosity @ -40°C, Poise is another indicator of lube performance at low temps. Lower the #, less the viscosity and gear/syncro drag.
Lower viscosity, especially at cruising temps, reduces gear/bearing drag thus increasing fuel mileage mpg, money in your pocket.
The ester real synthetic base stock in Redline lubes has another advantage, adhesion film to metal bonding.
Esters have all the advantages of a PAO but more of them. Esters can handle heat better than PAO’s and when burned, esters leave far less coking deposits. Esters are static types of oils and are attracted to metal parts with an electro-chemical bond. This means no more metal to metal start ups. This also means that a film is there before the oil pressure light goes out preventing premature wear of high-stressed parts like cam lobes. The film created is up to 5 times stronger then petroleum oil.
The number one reason to run an ester synthetic oil is bond. The electro-chemical bond is made because the ester molecule is polar. Sort of like a refrigerator magnet. It is attracted to metal and sticks.The PAO molecules are neutral and act like a piece of plastic placed on the fridge. They just fall off. All commercial jet plane flying, use an ester synthetic of some type and not a PAO. You need to run an ester of some sort for maximum protection.
Friction modifiers, antiwear additives and extreme pressure additives types and amounts used in the additive package to the base lube all affect how syncros function, cold and hot. They are not the same between brands of lube oil.
MTL for cold climates and/or NO>Lt. loads
Vis @ 100°C, cSt 10.6
Vis @ 40°C, cSt 56.2
Viscosity Index 183
Pour Point, °C -50
Pour Point, °F -58
Mobil Delvac Synthetic Transmission Fluid 50
I'd only use to reduce gear/shaft chatter if objectionable after conversion to a non DM clutch.
SAE Grade 50
Viscosity, ASTM D 445
cSt @ 40ºC 132
cSt @ 100ºC 17.5
Viscosity Index, ASTM D 2270 146
Pour Point, ºC, ASTM D 97 -45
I run a gallon of Delvac and 3 qts of Amsoil 5-30 synchromesh. Somewhat stiff after sittin overnight,even here in San Diego. To be honest,the truck shifted great w/ Amsoil ATF or Pennsoil synchromesh. After 20K with each, fluid looked like new and magnet had minimal fuzz. Just can't stand the marbles rattling around under the floorboard after the dmf was replaced.
I wish somebody'd come out with an iron case or a 60 hp+ DMF that would survive a 100K. I miss that silent,great shifting stock setup.
What would your recommendation be for a smf converted G-56?
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