Let Me Know if You Have Allison Transmission Fluid Questions

Jarlaxle wrote:

hzjcm8 wrote:

Jarlaxle wrote:

hzjcm8 wrote:

Jarlaxle wrote:

hzjcm8 wrote:
Hi all,

I've just joined Good Sam Club. I was the former Transmission Fluids Engineer at Allison Transmission. I held that position from 1990 until my retirement in 2009. Let me know if you have questions about TranSynd, the TES-295 specification or just anything to do with automatic transmission fluids. I'm here to help.

My Genesis has an MT643 trans behind a DT466 engine...Dexron III, right?

Nope !!! I no longer recommend anyone use DEXRON-III. Use TranSynd or another TES-295 for the best possible performance and durability. DEXRON-III is an obsolete spec so anything these days is being manufactured under the label D3/M meaning DEXRON-III/MERCON. These fluids are manufactured and sold but have no license and are no longer approved by either GM or Ford. I used to sit on the GM DEXRON-III committee and I can tell you that these fluids are no longer evaluated by anyone at GM. So, it's sort of like "buyer beware" when it comes to any DEXRON-III (D3M) products on today's market. Also, do not use DEXRON-VI due to possible seal issues with your older MT transmission.

PS: D3M fluids (DEXRON-III) tend to lose viscosity so cooling won't be as good due to lower cooling circuit flow. Unless you change it every 25,000 miles. So, just put in TranSYnd adn you should be good for at least 100,000 miles. Don't forget to change the filters too.

It's wound up 307,000 miles (filters changed annually, roughly 25K) on D3...honestly, I'm leery of switching it at this point! Is TranSynd compatible with D3? Flushing all of the old fluid out at this point is just not feasible short of component replacement. (This thing has the biggest trans cooler I have ever seen!)

Also, what (if anything) can you tell me about the oddball AT500?

If you've had success with DEXRON-IIIH, it's because you've been changing it and paying attention to the filter changes too. However, these fluids are no longer licensed products and I'm leary of them. The AT500 is an older Allison automatic with 4 speeds. It has hydraulic controls. Most every school bus in America had an AT500 at one time. It's a good transmission but a little low on cooler flow at idle. No electronics and it has a mechanical governor (no speed sensors).

Actually, by the records I got, they NEVER did a full ATF change...just an annual filter change. The fluid is clean & bright red (it is definitely Dexron III), it shifts perfectly.

I have to admit that I have looked at LOTS of school buses and have NEVER seen an AT500. Most (T444E, Cummins 5.9, Ford 6.6, Cat 3116, DD 8.2, DT360, IH 9.0 litre) had the AT542 or AT545 light-duty, non-lockup transmissions...3208 Cats or DT466 engines usually had MT643's (though I saw one DT466/AT545, and cannot fathom why someone would spec THAT out!), some pushers had T444E's and MD3060's. As I recall, the AT500 is essentially a lockup AT545...isn't it? I've only seen a few, all behind 5.9 Cummins engines in Freightliner chassis shuttle buses & delivery trucks.

My bus doesn't have a trans temp gauge...where should the sensor for one go on a 643?

Jaraxle,

Not sure how you know it's definitely DEXRON-III if you have no records. So, keep doing what you're doing ... sounds like it works for you. Good Luck !!!

PS: You asked about the AT500 so I thought you meant the AT500 Series which includes the AT542 and AT545. I did not differentiate between model types. In general, the AT500 Series was the fore runner to the 1000 Series. I'm not sure about placing the MT643 temperature sensor. That's out of my area of expertise but I'd say the best place would be the return line from the cooler if you can't catch the sump temperature anywhere.

I would rather drop the DEXRON-III conversation at this point because these fluids are getting very old now and who knows who's mixing them and with what ingredients.

Charlie D. wrote:
There have been, at times, much discussion about Dexron VI. Is it a synthetic, synthetic blend or what?

Thanks for all the great info. you have given.

Charlie D.,

DEXRON-VI is a mix of Group II and Group III base oils plus additives. A true synthetic will contain Group IV base oils which are called PAO (polyalphaolefins). TranSynd and the other TES-295 fluids all contain PAO only. Base oils are divided into these groups based on sulfur content, viscosity index, and amount of saturates.

To learn more about Base Oil Groups, go to API.org (American Petroleum Institute).

There have been, at times, much discussion about Dexron VI. Is it a synthetic, synthetic blend or what?

Thanks for all the great info. you have given.

hzjcm8 wrote:

Jarlaxle wrote:

hzjcm8 wrote:

Jarlaxle wrote:

hzjcm8 wrote:
Hi all,

I've just joined Good Sam Club. I was the former Transmission Fluids Engineer at Allison Transmission. I held that position from 1990 until my retirement in 2009. Let me know if you have questions about TranSynd, the TES-295 specification or just anything to do with automatic transmission fluids. I'm here to help.

My Genesis has an MT643 trans behind a DT466 engine...Dexron III, right?

Nope !!! I no longer recommend anyone use DEXRON-III. Use TranSynd or another TES-295 for the best possible performance and durability. DEXRON-III is an obsolete spec so anything these days is being manufactured under the label D3/M meaning DEXRON-III/MERCON. These fluids are manufactured and sold but have no license and are no longer approved by either GM or Ford. I used to sit on the GM DEXRON-III committee and I can tell you that these fluids are no longer evaluated by anyone at GM. So, it's sort of like "buyer beware" when it comes to any DEXRON-III (D3M) products on today's market. Also, do not use DEXRON-VI due to possible seal issues with your older MT transmission.

PS: D3M fluids (DEXRON-III) tend to lose viscosity so cooling won't be as good due to lower cooling circuit flow. Unless you change it every 25,000 miles. So, just put in TranSYnd adn you should be good for at least 100,000 miles. Don't forget to change the filters too.

It's wound up 307,000 miles (filters changed annually, roughly 25K) on D3...honestly, I'm leery of switching it at this point! Is TranSynd compatible with D3? Flushing all of the old fluid out at this point is just not feasible short of component replacement. (This thing has the biggest trans cooler I have ever seen!)

Also, what (if anything) can you tell me about the oddball AT500?

If you've had success with DEXRON-IIIH, it's because you've been changing it and paying attention to the filter changes too. However, these fluids are no longer licensed products and I'm leary of them. The AT500 is an older Allison automatic with 4 speeds. It has hydraulic controls. Most every school bus in America had an AT500 at one time. It's a good transmission but a little low on cooler flow at idle. No electronics and it has a mechanical governor (no speed sensors).

Actually, by the records I got, they NEVER did a full ATF change...just an annual filter change. The fluid is clean & bright red (it is definitely Dexron III), it shifts perfectly.

I have to admit that I have looked at LOTS of school buses and have NEVER seen an AT500. Most (T444E, Cummins 5.9, Ford 6.6, Cat 3116, DD 8.2, DT360, IH 9.0 litre) had the AT542 or AT545 light-duty, non-lockup transmissions...3208 Cats or DT466 engines usually had MT643's (though I saw one DT466/AT545, and cannot fathom why someone would spec THAT out!), some pushers had T444E's and MD3060's. As I recall, the AT500 is essentially a lockup AT545...isn't it? I've only seen a few, all behind 5.9 Cummins engines in Freightliner chassis shuttle buses & delivery trucks.

My bus doesn't have a trans temp gauge...where should the sensor for one go on a 643?

FreshAir wrote:
Tom, Could you please enlighten me as to what kind of equipment and expertise is required to perform an oil analysis. I envision a spotless room of Chem. Engineers clad in white lab coats feeding oil samples into mass spectrometers and jotting down figures while bent over electron microscopes.

I'm sure this is not the case and would greatly appreciate it if you could clear this up for me with a brief overview of what a typical analysis shop consists of and it's operation.

Thank's
Pat

PS, sorry if this has been explained in a previous post.

FreshAir,

You're describing a medical lab. Though most oil analysis labs are similar in nature, they are not under such tight controls as those doing blood analysis, forensic pathology, cancer research, etc. Chemists are usually in charge of lab operation, test calibration, etc. but the actual test operators typically are not chemists. Oh, and typically oil analysis lab personnel aren't as "good looking" as the ones on TV (CSI, Bones, CSI Miami, etc.).

Tests are run in accordance with ASTM (American Society for Testing and Materials) procedures. Typical tests are ICP (Inductive Coupled Plasma) for wear, contamination, and additive metals. Viscosmeters for viscosity at 100C. Contaminants by GC (Gas Chromotography) and FTIR (Fourier Transform Infra-Red). Total Acid Number (TAN) and/or Total Base Number (TBN) for titration of KOH (Potassium Hydroxide) and Oxidation/Nitration by FTIR. Condemning limits are set based on an historical database of like equipment and like oils.

I personally have great respect for what oil analysis can do and used it everytime I ran a field test for Allison.

Hope this helps!!

Tom, Could you please enlighten me as to what kind of equipment and expertise is required to perform an oil analysis. I envision a spotless room of Chem. Engineers clad in white lab coats feeding oil samples into mass spectrometers and jotting down figures while bent over electron microscopes.

I'm sure this is not the case and would greatly appreciate it if you could clear this up for me with a brief overview of what a typical analysis shop consists of and it's operation.

Thank's
Pat

PS, sorry if this has been explained in a previous post.

belfert wrote:
The big question I have is how can I save money on TES 295 approved fluid?

Most of the TES 295 approved fluids on the Allison list I can't find for sale. If I can find them for sale they cost as much or more than Transynd. I have numerous places I can find Transynd locally.

I probably should change my Transynd as it has been almost 5 years and 25,000 miles. The fluid should probably have been chnaged even earlier as I had non TES 295 fluid in there before so I have a mix right now.

belfert,
Sorry but they're all expensive because they're all true synthetics (PAO, polyalphaolefin) based. That's what's keeping the cost high; however, if you take full advantage of the drain intervals, you'll still be money ahead. I wouldn't change your fluid unless oil analysis condemns it. If it's a mixture, that will show up in the viscosity. If it's above 6.5 cSt (centiStokes) at 100C then it's probably still good. If you change filters, just top it off with TranSynd or a TES-295 product and you should be OK. Oil analysis will tell you.

bsimonds wrote:

hottubkid wrote:
Of the differance between the two types of transmission fluid? As I understood in the response to me they all could be red ect

bsimonds wrote:

hzjcm8 wrote:

SpinRite wrote:
Hi, hzjcm8,

If using this method:
1. Drain old Dexron and re-fill with Transynd.
2. Remove return hose from transmission cooler and aim it into a bucket.
3. Have a helper start engine, then shut it down as soon as you see fluid color going into the bucket change over to Transynd.
4. Re-connect hose, top off with Transynd.

Does this only replace the fluid in the cooler, or does it also take care of the torque converter?

Spinrite,

Your technique is OK (kind of like a flushing machine but better). Just make sure you get the cooler hoses tight. Your technique gets everything (sump, torque converter, cooler, cooler lines). As soon as you start the engine the transmission pump is turning and will pump fluid through the torque converter and to the "converter out" circuit which is "cooler in".

No problem !!!

PS: The reason I didn't mention this is because most folks won't go to the measure and Allison doesn't recommend it for most people. The double drain does the same thing.

How do you identify which cooler line is the return?

Spinrite said "2. Remove return hose from transmission cooler. . . "
My question was of the two cooler lines, how do you know which one is the "return hose"?

Spinrite,

The return hose is known as "Cooler Out" meaning it's the cooled oil coming from the cooler. This hose connects to the "From Cooler" port on the transmission. So, the return line is connected to the "From Cooler" port. The other line is going to the cooler and is connected to the "To Cooler" port on the transmission.

wolfe10 wrote:

hzjcm8 wrote:

mci7 wrote:
Reference to the 4000MHR transmission, using the Detroit TranSynd oil, What would the max safe temp allowed when decending a mountain using the retarder ?
So far, have not let it go above 220F.
Many thanks

MCI7,

I would say you could let it get to 250F but only intermittently. The transmission will allow a max "converter out" temperature of 330F so 220F sump temperature is not too high. The transmission will go into the "inhibit" mode to allow better cooling once it reaches a pre-set sump temperature but I'm not sure what that point is. I'm thinking it's probably around 250F though.

Tom,

Let's back up a minute. There are three different (very different) location for the transmission temperature senders on RV's I have worked on. I have seen them at the transmission sump, line into the transmission cooler and the line out of the transmission cooler.

Each will have a maximum recommended temperature, with the sump temperature likely being the most "accurate" and critical in reflecting what is happening in the transmission.

If you could share temps for each of these locations, it would be of assistance, as the readings are so different.

mci7,

Converter out ("To Cooler") will be the highest temperature. Allison allows 330F max converter out temperature before the electronics will inhibit functionality to try to cool the transmission. Sump will be typically between 180F and 220F. The lowest temperature should be "From Cooler". The temperature drop across the cooler is dependent upon air flow, surface area and cooler flow. I would pay the most attention to the sump temperature since it is a function of the cooler circuit design and flow. It should be the most stable since cooler in and cooler out temperatures vary more depending on how much you operate in converter mode vs. lockup mode and have less of a "heat sink" affect meaning the heat disipation rate (heat transfer) will be more efficient in the smaller mass of the converter in and out sensors.

I really can't give you much info on typical cooler in and out temperatures.

hottubkid wrote:
Of the differance between the two types of transmission fluid? As I understood in the response to me they all could be red ect

bsimonds wrote:

hzjcm8 wrote:

SpinRite wrote:
Hi, hzjcm8,

If using this method:
1. Drain old Dexron and re-fill with Transynd.
2. Remove return hose from transmission cooler and aim it into a bucket.
3. Have a helper start engine, then shut it down as soon as you see fluid color going into the bucket change over to Transynd.
4. Re-connect hose, top off with Transynd.

Does this only replace the fluid in the cooler, or does it also take care of the torque converter?

Spinrite,

Your technique is OK (kind of like a flushing machine but better). Just make sure you get the cooler hoses tight. Your technique gets everything (sump, torque converter, cooler, cooler lines). As soon as you start the engine the transmission pump is turning and will pump fluid through the torque converter and to the "converter out" circuit which is "cooler in".

No problem !!!

PS: The reason I didn't mention this is because most folks won't go to the measure and Allison doesn't recommend it for most people. The double drain does the same thing.

How do you identify which cooler line is the return?

Spinrite said "2. Remove return hose from transmission cooler. . . "
My question was of the two cooler lines, how do you know which one is the "return hose"?