Synthetic oil in the tranny

[XTOAK]

Has anyone heard of a GM dealer or GM discouraging owners from switching to synthetic oil in the tranny and transfer case? I know it's factory in the rear differentials on the 2500 04's and in the northern climates the dealers switch the front diff to syn due to the TSB for cold climates, but what about the tranny and t-case? I've got a friend who was told yesterday by the local dealer that they don't recommend synthetic in the tranny or transfer case? Anybody else been told that?

[SilveradoWV]

I have heard that before, but also hears people say they are switching to synthetic.

[DJinCO]

That's funny. My dealer recommended that I switch to synthetic and actually recommended Amsoil ATF. I guess it depends on the dealership.

 

Cheers, Doug

[tmf6902]

With the allison it doesn't make any differance

 

Q. Automatic Transmission Fluid (ATF) - Can I use synthetic fluid? 

A. Any fluid that meets DEXRON III requirements is suitable for use in the Allison 1000 Series™. Always verify that the container reads DEXRON III, regardless of whether it is mineral-based or synthetic.

 

That's straight off their website.

[awdvkd]

Synthetic ATF is really a sound decision to make. The break temp is about 20-25 degrees higher than standard dino ATF. I really noticed a big difference in the driveablity on my allison when I changed it out. It runs cooler, shifts better and last longer. When I changed over I really didn't expect much difference, but I was really impressed with the difference it made. I tow alot and just the higher break down temps and the extra protection was what I was looking for. When you consider it cost 6-7k to buy a new one the extra cost of synthetics are worth it. My truck is synthetic front to back bumper (Mobil 1). Hope this helps.

[JayMan]

Synthetic ATF is really a sound decision to make. The break temp is about 20-25 degrees higher than standard dino ATF. I really noticed a big difference in the driveablity on my allison when I changed it out. It runs cooler, shifts better and last longer. When I changed over I really didn't expect much difference, but I was really impressed with the difference it made. I tow alot and just the higher break down temps and the extra protection was what I was looking for. When you consider it cost 6-7k to buy a new one the extra cost of synthetics are worth it. My truck is synthetic front to back bumper (Mobil 1). Hope this helps.

A friend of mine with a 2002 GMC Sierra D/A did the initial Allison service at 600 miles: pan drain and new spin-on using Mobil 1 ATF. He did the service again at 1,200 miles.

 

We dropped that huge pan and it was spotless inside at 600 and at 1,200. My friend is an independent field service tech and needs to depend on his truck, even at -40 F, and it has to last him forever.

 

He serviced it again last summer with around 63,000 miles on it. For some reason, he talked me into helping him drop the pan again. Spotless. The Allison shifts very smoothly, even at -40. No herky-jerky or mushiness at all. The synthetic really helps.

 

Especially for a cold climate you'll see major benefits.

 

If you have an automatic transfer case or "AutoTrak" then you MUST use the dealer AC Delco AutoTrak II fluid. Failure to use the proper fluid, such as using a regular or synthetic Dex III instead, can cause the clutch pack to fail.

 

The AC Delco stuff seems to be synthetic anyway. Last week at -40, I checked the bottle I have in the shed where I keep my snowblower. The fluid seemed quite fluid, normally a non-synthetic at that temp is hard as a rock or sluggish. Seemed fine, and my truck's AutoTrak works well even at -40.

[JayMan]

Has anyone heard of a GM dealer or GM discouraging owners from switching to synthetic oil in the tranny and transfer case? I know it's factory in the rear differentials on the 2500 04's and in the northern climates the dealers switch the front diff to syn due to the TSB for cold climates, but what about the tranny and t-case? I've got a friend who was told yesterday by the local dealer that they don't recommend synthetic in the tranny or transfer case? Anybody else been told that?

Wait a minute.

 

Your signature claims you're in Alaska and your dealer does NOT want you running synthetics?? That is INSANE.

 

A 15W-40 for the Duramax is frozen solid by -30 F, and by -45 F you'd need a hammer and chisle to get it out of the bottle. Even though the new Mobil Delvac 1 5W-40 is thicker than it used to be, it should still be good at -40 F.

 

Cat HD engine dealers offer a full synthetic 0W-30 HD diesel engine oil that's good for VERY low temps. If you can find Esso or Exxon XD-3 0W-40, that's also good at low temps.

 

The front axles are factory filled with a regular GL-5 80W-90. That garbage turns hard as a rock by -15 F. Another commercial gear lube, Mobil MobilLube SHC 75W-90, is good to about -50 F.

 

Folks think regular ATF is very light, and it is to a certain point. Though it will also turn hard as a rock at -42 F, and should NOT be used in temps colder than -34 F. Mobil 1 ATF is good to about -50 F.

 

The rear axle is a factory-fill synthetic 75W-90, so that should be fine.

 

The regular 2-speed transfer case uses regular ATF, so put in a synthetic. The AutoTrak already appears to use a factory synthetic.

 

Cripes. That's almost as bad as a dealer in the Canadian Yukon recommending a 15W-40 in January!

[XTOAK]

Jayman, I hear ya. I couldn't believe it either as I've got the syn in the front and rear diffs, as well as the motor, and was about to switch to syn in the transmission and t-case but was told the dealer didn't recommend it. I plan on doing the switch this weekend but wanted to check first to make sure I wouldn't regret it later.

 

It was -11 last night and all I kept thinking on the drive to work this morning was how much longer that tranny would last over time if it had synthetic in it.

 

A coworker who frequents this board bought a new Chevy a couple weeks ago and the front diff seized up on him two days ago. The dealer admitted he forgot to change the front diff to synthetic per the TSB...and the same fella who says putting syn in a tranny or t-case is a no-no. Gee, wonder how many trannies and t-cases it takes for him to replace after the warranty to pay for that six week vacation on a warm, sunny island?

[JayMan]

Jayman, I hear ya. I couldn't believe it either as I've got the syn in the front and rear diffs, as well as the motor, and was about to switch to syn in the transmission and t-case but was told the dealer didn't recommend it. I plan on doing the switch this weekend but wanted to check first to make sure I wouldn't regret it later.

 

It was -11 last night and all I kept thinking on the drive to work this morning was how much longer that tranny would last over time if it had synthetic in it.

 

A coworker who frequents this board bought a new Chevy a couple weeks ago and the front diff seized up on him two days ago. The dealer admitted he forgot to change the front diff to synthetic per the TSB...and the same fella who says putting syn in a tranny or t-case is a no-no. Gee, wonder how many trannies and t-cases it takes for him to replace after the warranty to pay for that six week vacation on a warm, sunny island?

I figure about 5 tranny rebuilds, or 2 transfer case rebuilds. Then he jets off to sunny funny Cancun. Maybe the Gods of Irony will smile at him and he'll catch a nasty butt worm.

 

For an automatic transmission, the low temp Brookfield Viscosity should never exceed 100 Poise. Beyond that the torque coverter fails. Have you ever seen duma** folks at -40 who somehow manage to get their car started, then slam the selector into Drive and nothing happens?

 

Then they floor the gas pedal, somehow thinking that "helps?"

 

Oi!

 

 

At -40 F, Mobil 1 ATF has a rated Brookfield viscosity of 51.5 Poise, so it's still quite safe to use. If you have a regular two speed transfer, you will notice much improved cold weather operation.

 

Since I run commercial equipment, I have pails of commercial gear lube in my shop. I run Mobil MobilLube SHC 75W-90 in my front axle, Mobil 1 0W-30 in my Vortec 5.3, the dealer AC Delco AutoTrak II in my AutoTrak transfer case, Mobil 1 ATF in the automatic, and Mobil 1 Gear Oil 75W-90 in my rear axle (Need the LS additives).

 

Even at -40 f, no problems and the shift from 2WD to 4WD is instant.

 

Remember, if you have the AutoTrac automatic transfer case - it has a button labeled AUTO 4WD - you must use the dealer fluid. It's blue, like a Smurf.

[XTOAK]

You'd be surprised what I saw growing up in Fairbanks in the sixties and seventies...-50 can do a real bunch of ugly on a tranny...especially some of those folks who built the pipeline and hadn't ever driven a vehicle in those temps.

 

I have always sworn by synthetics and was going to do the switch on the tranny and t-case but thought I'd better check before doing so in the even Chevy had seen in their wisdom to change something. Now I know it's not Chevy but the dealership.....

[JayMan]

You'd be surprised what I saw growing up in Fairbanks in the sixties and seventies...-50 can do a real bunch of ugly on a tranny...especially some of those folks who built the pipeline and hadn't ever driven a vehicle in those temps.

 

I have always sworn by synthetics and was going to do the switch on the tranny and t-case but thought I'd better check before doing so in the even Chevy had seen in their wisdom to change something. Now I know it's not Chevy but the dealership.....

Oh, I've seen some beauts too.

 

Like a car with the oil frozen so hard it won't even crank. So the duma** gets a boost and sprays a can of Ether to get it going. The oil pump drive shears right off and no oil pressure.

 

When I see s*** like that, I just KNOW that Darwin was right. Not about everything, but he sure was right about THAT.

 

I'm not sure if I get as cold as you folks do. In places like Saskatchewan, Manitoba, and North West Ontario, the mercury can dip pretty low too. Last week it was -42 F, though it has "warmed up" to -25 F. That's ambient temp, never mind the windchill when I was shoveling the path to my garage.

 

Remember that synthetic oils were invented for the U.S. Air Force, since a jet engine at high alititude will see outside air temps of -65 F. Folks like us benefit from their use in the automotive world.

 

I first switched to synthetics 22 years ago. At the time, I was only after one thing: cold temp use. I wanted my equipment to start and run without puking up a conrod. I figure the better high temp performance, extended drains, and much longer life are added benefits.

[JayMan]

With the allison it doesn't make any differance

 

Q. Automatic Transmission Fluid (ATF) - Can I use synthetic fluid? 

A. Any fluid that meets DEXRON III requirements is suitable for use in the Allison 1000 Series™. Always verify that the container reads DEXRON III, regardless of whether it is mineral-based or synthetic.

 

That's straight off their website.

Actually, most HD Allison dealers in Canada strongly recommend the use of a synthetic ATF. Of course, they'll try to sell you their outrageous TranSynd for HD operators, but if you growl about the price, then they'll suggest something like Mobil 1 ATF, which has dual Dexron III and Allison C4 certification.

 

The Allison owner's manual has a warning about cold temp use, primarily when you have to do the "preheat" before using the transmission.

 

With a regular mineral DexIII ATF, that preheat temp is -12 F or colder. With a synthetic, -22 F or colder. Preheat means either using an electric pan heater, or running the motor with the automatic in Park or Neutral for 20 minutes.

 

Allison cautions that using a fluid too thick for ambient temps can result in torque converter failure, heavy wear, and early failure.