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6.5 transmission/rear differential: fluid type and amount
- Thread starter Tovar
- Start date
JayTheCPA
Well-Known Member
For the tranny, read here: http://www.thetruckstop.us/forum/threads/tranny-fluid-urban-legend-true-or-not.45638/
For the rear and transfer, cannot really go wrong with synthetic. In my DI rig, I instantly gained 1/2 mpg when I switched those two from dyno to synthetic. For some reason the 6.5 did not change mileage, but the tach dropped by ~200 RPM's. Not sure why the 6.5 only made a RPM change, but am still happy with the decision.
For the rear, consider an aftermarket cover that holds more fluid and allows better cooling.
For the rear and transfer, cannot really go wrong with synthetic. In my DI rig, I instantly gained 1/2 mpg when I switched those two from dyno to synthetic. For some reason the 6.5 did not change mileage, but the tach dropped by ~200 RPM's. Not sure why the 6.5 only made a RPM change, but am still happy with the decision.
For the rear, consider an aftermarket cover that holds more fluid and allows better cooling.
Twisted Steel Performance
Anything worth doing is worth overdoing.
For the rear end towing I recommend 85W140, and like Jay stated a bigger cover will help..
Jaythecpa...just read the thread you gave me. Raises more questions than answers. Doesn't the filter need to be changed? What is the process? Drain the pan, replace filter, then reuse the ATF. Trucks got a little over 100,000 miles on it.
- Staff
- #6
For ATF, go with a DEXRON 3 type fluid, or a DEX/MERC fluid. Stay FAR away from anything that says DEX VI on it as your seals in your 99 trans will not be compatible with it. Drain the pan, drop it, change the filter out, then put it back together with fresh fluid. As to your rear end, it should be a DANA 80 if you have an actual 3500HD. A diff cover isn't a bad idea, but not needed. As to fluid, 80W90 is what they call for, but you can run 85W140 if you want to. 75W140 is another good fluid to run. A bit on the pricier side, but it is very good stuff. It has all the benefits of 75W90 fluid when cold, as well as all the benefits of 85W140 when hot. As to amounts, I'm not 100% certain, but I believe the trans will be around 6-9 quarts depending on how long you let it sit and drain, and which pan it has on it(GM used both deep and shallow pans on the 4L80E). Rear diff should be between 3-4 quarts, and you will probably need a bottle of posi slip additive for it because DANA used clutch type posi diffs if it has one in it.
hatzie
New Member
There is no such thing as Dexron III and hasn't been for nearly a decade. Anything that says Dexron III on the bottle is untested by GM. I run Dexron VI in my GM automatic transmissions. It's downward compatible and works just fine in the TH200R4, TH350, TH400, 4L60, 4L80, & TH700R4.
Dexron VI is cheaper and more available than claimed equivalents to Dexron III. Anything that says Dexron VI on the label is GM licensed and tested. WalMart Supertech brands work fine.
If you have the NV4500 the special GM or Mopar NV4500 specific fluids are the only ones to run unless you feel like replacing synchros. They ain't cheap.
The 14bolt takes 80W90 gear oil don't use heavier oils they'll run too hot. You'll get better fuel mileage with synthetics. DO NOT use limited slip additive with the G80 locker. Limited slip additive shouldn't be used unless you have an aftermatket LSD that specifically calls for it.
Sent from my SM-P605V using Tapatalk
Last edited:
hatzie
New Member
More on Dexron VI from GM & the LS4 board...
It's not applicable to the 6.5L trucks but is worth noting that the Allison 1000 has very specific care and feeding instructions... Some use Dexron VI some do not. Look up the bulletins based on serial number and follow their reccomendations.
From a GM tech bulletin:
Although DEXRON-VI (fig. 1) was introduced into production starting with 2006 model year vehicles (see bulletin 04-07-30-037D), there are still some misunderstandings about it. Here are some facts to help clear up these misunderstandings.
Since GM introduced the first service-fill specification for automatic transmission fluid (ATF) in 1949, it has been necessary periodically to upgrade the specification as part of a continuous improvement strategy. The upgrading process ensures that available service fill fluids are of an appropriate quality for use in transmissions that have been designed around the improved factory fill fluid performance.
IMPORTANT: As with previous upgrades, DEXRON-VI fluids are designed to be backward compatible with earlier transmission hardware. But more important, earlier type fluids are NOT FORWARD COMPATIBLE with transmissions that were designed to use DEXRON-VI.
DEXRON-VI can be used in any proportion in past model vehicles equipped with an automatic transmission, in place of DEXRON-III (for instance, topping off the fluid in the event of a repair or fluid change). DEXRON-VI is also compatible with any former version of DEXRON for use in automatic transmissions.
TIP: Simply topping off the fluid is adequate, but a full drain and replacement is preferred, to obtain the full benefit.
IMPORTANT: DEXRON-VI Automatic Transmission Fluid (ATF) is the only approved fluid for warranty repairs for GM transmissions requiring DEXRON-III or prior DEXRON transmission fluids.
TIP: Any vehicle that previously used DEXRON-III for a manual transmission or transfer case should now use p/n 88861800 (88861801 in Canada) Manual Transmission and Transfer Case Fluid. And power steering systems should now use p/n 89020661 (89021183 in Canada) Power Steering Fluid.
TIP: Since some early bulletins were issued, further validation has taken place and certain transfer cases and manual transmissions now DO use DEXRON-VI, so it's important to refer to the owner manual for appropriate recommendations.
All licenses for DEXRON-III expired at the end of 2006 and will not be renewed. Fluids sold in the market after that date bearing claims such as "suitable for use in DEXRON-III applications" or similar wording should be avoided, because 'DEXRON-III' fluids are no longer checked and policed by GM and therefore may not be the originally tested and approved formulation.
ADVANTAGES OF DEXRON-VI
GM uses an ATF for factory fill that provides significantly improved performance in terms of friction durability, viscosity stability, aeration and foam control, and oxidation resistance. In addition, the fluid has the potential to enable improved fuel economy and extended drain intervals. The service fill specification for a fluid meeting these standards is designated as DEXRON-VI.
When compared with earlier automatic transmission fluids, DEXRON-VI offers these improvements and benefits:
- enhanced performance of both new and older transmissions
- longer ATF life (160,000 km/100,000 miles normal, or 80,000 km/50,000 miles severe). It is important to refer to the owner manual because certain vehicles recommend a normal service drain interval of 150,000 miles (240,000 km).
- consistent shift quality throughout the life of the transmission
- extended transmission life.
To achieve these benefits, DEXRON-VI offers significant improvements in these operating characteristics:
Friction Stability (improved 100%) -- Friction describes how the fluid behaves when transmission clutches or bands are engaged. A fluid with poor friction characteristics leads to grabbing, chattering and slipping (fig. 2).
DEXRON-VI also offers a 120% improvement in clutch durability (fig. 3).
A DEXRON-III
B DEXRON-VI
A Clutch operated with DEXRON-III
B Clutch operated with DEXRON-VI
Viscosity Stability (greatly improved) -- Viscosity is a description of how thick or thin a fluid is at various temperatures. In a hydraulic system, components can function sluggishly or improperly when viscosity is wrong. As determined by comparison testing (fig. 4),
DEXRON-VI maintains an almost constant viscosity over time, while the viscosity of DEXRON-III degrades considerably.
A DEXRON-III
B DEXRON-VI
Foaming Resistance (improved 150%) -- Automatic transmission fluid may contain air in three forms -- dissolved, entrained (aeration) and foam. Oil containing air doesn't do anything very well -- lubrication is affected, heat transfer in affected and pressures are unstable. Anti-foam additives are used to control and limit the effects of air in the fluid (fig. 5).
A DEXRON-III foam test
B DEXRON-VI foam test
Oxidation Resistance (improved 100%) -- Oxidation describes the length of time it takes for a fluid to reach the end of its useful life. Oxidation generally occurs more quickly at higher temperatures (fig. 6).
And oxidation has an effect on how long a fluid can be used before replacement is necessary.
A Aftermarket fluid oxidation test
B DEXRON-VI oxidation test
TIP: Just because another auto maker does not require use of DEXRON-VI, this does not imply that their required fluid is in any way inferior to or better than DEXRON-VI. It simply means that the other auto maker has established its own, unique fluid requirements. Their transmissions may be built with different materials, and may be designed to perform in different ways, neither of which is necessarily inferior to or better than GM's transmissions, just different. Variables include the material used for friction surfaces, the material used for reaction surfaces, the types of control mechanisms and the characteristics of the factory fill fluid. This means that each manufacturer must tailor their transmission fluid requirements to meet the needs of their own transmissions. And a fluid may cause entirely different performance when installed into transmissions of different designs.
COUNTERFEIT PRODUCTS
Beware products that claim to be DEXRON-VI but are not; for instance, some products claim to be multi-purpose. And beware the products which claim to provide DEXRON-VI characteristics when added to other ATFs. Unlicensed products have not been tested by GM to determine whether they meet GM's specifications.
ADDITIVES
DEXRON-VI is formulated to meet and exceed GM's specifications and requirements. Additives are not needed and are not recommended.
The best thing that can happen when using an additive is that it will do nothing. At worst, an additive can ruin the transmission.
DEALING WITH CONTAMINATION
Anything but DEXRON-VI in the automatic transmission is considered a contaminant. Typically, a customer or other service facility may add fluids other than DEXRON-VI. This includes aftermarket additives -- they are not needed and should not be used. In case like this:
- drain the transmission fluid
- flush the system with DEXRON-VI (NOT solvent)
- fill the system with the correct amount of DEXRON-VI.
Sent from my SM-P605V using Tapatalk
It's not applicable to the 6.5L trucks but is worth noting that the Allison 1000 has very specific care and feeding instructions... Some use Dexron VI some do not. Look up the bulletins based on serial number and follow their reccomendations.
From a GM tech bulletin:
Although DEXRON-VI (fig. 1) was introduced into production starting with 2006 model year vehicles (see bulletin 04-07-30-037D), there are still some misunderstandings about it. Here are some facts to help clear up these misunderstandings.
Since GM introduced the first service-fill specification for automatic transmission fluid (ATF) in 1949, it has been necessary periodically to upgrade the specification as part of a continuous improvement strategy. The upgrading process ensures that available service fill fluids are of an appropriate quality for use in transmissions that have been designed around the improved factory fill fluid performance.
IMPORTANT: As with previous upgrades, DEXRON-VI fluids are designed to be backward compatible with earlier transmission hardware. But more important, earlier type fluids are NOT FORWARD COMPATIBLE with transmissions that were designed to use DEXRON-VI.
DEXRON-VI can be used in any proportion in past model vehicles equipped with an automatic transmission, in place of DEXRON-III (for instance, topping off the fluid in the event of a repair or fluid change). DEXRON-VI is also compatible with any former version of DEXRON for use in automatic transmissions.
TIP: Simply topping off the fluid is adequate, but a full drain and replacement is preferred, to obtain the full benefit.
IMPORTANT: DEXRON-VI Automatic Transmission Fluid (ATF) is the only approved fluid for warranty repairs for GM transmissions requiring DEXRON-III or prior DEXRON transmission fluids.
TIP: Any vehicle that previously used DEXRON-III for a manual transmission or transfer case should now use p/n 88861800 (88861801 in Canada) Manual Transmission and Transfer Case Fluid. And power steering systems should now use p/n 89020661 (89021183 in Canada) Power Steering Fluid.
TIP: Since some early bulletins were issued, further validation has taken place and certain transfer cases and manual transmissions now DO use DEXRON-VI, so it's important to refer to the owner manual for appropriate recommendations.
All licenses for DEXRON-III expired at the end of 2006 and will not be renewed. Fluids sold in the market after that date bearing claims such as "suitable for use in DEXRON-III applications" or similar wording should be avoided, because 'DEXRON-III' fluids are no longer checked and policed by GM and therefore may not be the originally tested and approved formulation.
ADVANTAGES OF DEXRON-VI
GM uses an ATF for factory fill that provides significantly improved performance in terms of friction durability, viscosity stability, aeration and foam control, and oxidation resistance. In addition, the fluid has the potential to enable improved fuel economy and extended drain intervals. The service fill specification for a fluid meeting these standards is designated as DEXRON-VI.
When compared with earlier automatic transmission fluids, DEXRON-VI offers these improvements and benefits:
- enhanced performance of both new and older transmissions
- longer ATF life (160,000 km/100,000 miles normal, or 80,000 km/50,000 miles severe). It is important to refer to the owner manual because certain vehicles recommend a normal service drain interval of 150,000 miles (240,000 km).
- consistent shift quality throughout the life of the transmission
- extended transmission life.
To achieve these benefits, DEXRON-VI offers significant improvements in these operating characteristics:
Friction Stability (improved 100%) -- Friction describes how the fluid behaves when transmission clutches or bands are engaged. A fluid with poor friction characteristics leads to grabbing, chattering and slipping (fig. 2).
DEXRON-VI also offers a 120% improvement in clutch durability (fig. 3).
A DEXRON-III
B DEXRON-VI
A Clutch operated with DEXRON-III
B Clutch operated with DEXRON-VI
Viscosity Stability (greatly improved) -- Viscosity is a description of how thick or thin a fluid is at various temperatures. In a hydraulic system, components can function sluggishly or improperly when viscosity is wrong. As determined by comparison testing (fig. 4),
DEXRON-VI maintains an almost constant viscosity over time, while the viscosity of DEXRON-III degrades considerably.
A DEXRON-III
B DEXRON-VI
Foaming Resistance (improved 150%) -- Automatic transmission fluid may contain air in three forms -- dissolved, entrained (aeration) and foam. Oil containing air doesn't do anything very well -- lubrication is affected, heat transfer in affected and pressures are unstable. Anti-foam additives are used to control and limit the effects of air in the fluid (fig. 5).
A DEXRON-III foam test
B DEXRON-VI foam test
Oxidation Resistance (improved 100%) -- Oxidation describes the length of time it takes for a fluid to reach the end of its useful life. Oxidation generally occurs more quickly at higher temperatures (fig. 6).
And oxidation has an effect on how long a fluid can be used before replacement is necessary.
A Aftermarket fluid oxidation test
B DEXRON-VI oxidation test
TIP: Just because another auto maker does not require use of DEXRON-VI, this does not imply that their required fluid is in any way inferior to or better than DEXRON-VI. It simply means that the other auto maker has established its own, unique fluid requirements. Their transmissions may be built with different materials, and may be designed to perform in different ways, neither of which is necessarily inferior to or better than GM's transmissions, just different. Variables include the material used for friction surfaces, the material used for reaction surfaces, the types of control mechanisms and the characteristics of the factory fill fluid. This means that each manufacturer must tailor their transmission fluid requirements to meet the needs of their own transmissions. And a fluid may cause entirely different performance when installed into transmissions of different designs.
COUNTERFEIT PRODUCTS
Beware products that claim to be DEXRON-VI but are not; for instance, some products claim to be multi-purpose. And beware the products which claim to provide DEXRON-VI characteristics when added to other ATFs. Unlicensed products have not been tested by GM to determine whether they meet GM's specifications.
ADDITIVES
DEXRON-VI is formulated to meet and exceed GM's specifications and requirements. Additives are not needed and are not recommended.
The best thing that can happen when using an additive is that it will do nothing. At worst, an additive can ruin the transmission.
DEALING WITH CONTAMINATION
Anything but DEXRON-VI in the automatic transmission is considered a contaminant. Typically, a customer or other service facility may add fluids other than DEXRON-VI. This includes aftermarket additives -- they are not needed and should not be used. In case like this:
- drain the transmission fluid
- flush the system with DEXRON-VI (NOT solvent)
- fill the system with the correct amount of DEXRON-VI.
Sent from my SM-P605V using Tapatalk
Last edited:
Will L.
Well-Known Member
I am not a transmission guy, but rebuilt a few. I an not a petroleum engineer, but worked hand in hand with tons of them for years. I have operated small scale distilleries. I was ase certified master auto, med and heavy duty trucks, and truck equipment master. Owned shops, worked for many more.
Here is what I know. GM has a long history of claiming perfection and ALWAYS ONLY recommends thier product line. They dont always get it right (coughdexcoolcough).
When they lost the ability to make money from dextron 3, then they released dextron 6. Anybody buy any dextron 4 or 5? Hmmm. Do some research.
There IS some problems with running dex6 in the older ones. Dont care if you agree or not.
THE SAME OIL DISTILLERIES THAT WERE MAKING DEXTRON 3 ARE STILL MAKING DEXTRON 3. The GM stamp of approval went away because they dont get paid for it anymore. What was the name/ location of the GM OWNED OR OPERATED DISTILLERY? Additives being an issue? Wtf? You think GM has a magic temperature and pressure combo that pulls oil off a bubble sieve tray so great they dont add the additives to it that are the same exact additives every single distillery cuts in?
60% of the dextron3 that has been produced in the US since it inception came from 1 distillery. Know which one? I do. I have turned a few valves there. They are still making the same exact quantity the used to. Don't panic people because of a marketing ploy by GM. If the new stuff was all together better and caused no problems, I would be agreeing with you. I have nothing for or against GM's oil loyalty. GM only changed because they lost the legal right to charge for it, and did the best they could as fast as they could. The antifoam additive btw is the same one they beat up ford about thats so heavy in type f. Now that they need a spec quanitity so far from "x", it is magically the perfect amount. Hmm.
Over it.
Here is what I know. GM has a long history of claiming perfection and ALWAYS ONLY recommends thier product line. They dont always get it right (coughdexcoolcough).
When they lost the ability to make money from dextron 3, then they released dextron 6. Anybody buy any dextron 4 or 5? Hmmm. Do some research.
There IS some problems with running dex6 in the older ones. Dont care if you agree or not.
THE SAME OIL DISTILLERIES THAT WERE MAKING DEXTRON 3 ARE STILL MAKING DEXTRON 3. The GM stamp of approval went away because they dont get paid for it anymore. What was the name/ location of the GM OWNED OR OPERATED DISTILLERY? Additives being an issue? Wtf? You think GM has a magic temperature and pressure combo that pulls oil off a bubble sieve tray so great they dont add the additives to it that are the same exact additives every single distillery cuts in?
60% of the dextron3 that has been produced in the US since it inception came from 1 distillery. Know which one? I do. I have turned a few valves there. They are still making the same exact quantity the used to. Don't panic people because of a marketing ploy by GM. If the new stuff was all together better and caused no problems, I would be agreeing with you. I have nothing for or against GM's oil loyalty. GM only changed because they lost the legal right to charge for it, and did the best they could as fast as they could. The antifoam additive btw is the same one they beat up ford about thats so heavy in type f. Now that they need a spec quanitity so far from "x", it is magically the perfect amount. Hmm.
Over it.
- Staff
- #10
If you feel comfortable using it, by all means go ahead. I will NEVER reccomend the stuff. GM came out with simply because there patent was running out, they needed something to help with CAFE ratings, and so in comes DEX VI for them to now approve. The DEX III rating is still active essentially, just look for TES-389 approval as it is the SAME as DEX III, just ALLISON's version of it. To me, I could care less if the general approves it seeing how many things they've botched. I still to this day will ONLY run DEX/MERC fluid in anything that called for DEX III, but thats me. Several of us have removed DEX VI, and went back to DEX/MERC fluids or better yet a TES-295 fluid. Thats just my $.02 on it though.