Replacement Allison Trans fluid info requested

[JEBar]

Currently have just over 15,000 miles on my D/A... on page 6-26 of my owners manual it states (in bold print) "Notice: We recommend you use only fluid labeled Dextron-III, because fluid with that label is made especially for your automatic transmission. Damage caused by fluid other than Dextron-III is not covered by your new vehicle warranty." Questions: What synthetic fluids are certified to meet GM specs so that if a problem results, warranty would be valid? I understand (from info on another forum) that Allison transmissions which are in vehicles with door dates of 1/02 or later come with synthetic fluid. If this is true, what is the name of that fluid? Any advise would be greatly appreciated. :confused:

[csimo]

Most synthetic fluid manufactureres have Dexron III rated fluids. I use Red Line High-Temp synthetic, but there are others probably just as good. Just make sure it's Dexron III rated, and if it's GL-4 rated it's a notch better.

Allison has a fluid called Transynd that is probably the finest synthetic transmission fluid made. There are some other brands that claim to match Transynd, but none have been approved by Allison to date. Transynd is also very expensive!

If you don't do any towing the non-synthetic fluid will be fine. The "Dexron III" standard is very specific for friction modifiers and both synthetic and standard fluid have to meet those specifications. Neither is better in this regard. The synthetic fluid is much better when it comes to heat. Synthetic can withstand much higher temps. without break down, and dissapates heat faster.

On a side note... there are many companies that have made their reputation on extended drain intervals for synthetic lubricants. Don't believe them, and I wouldn't use such a product for that purpose. Both conventional and synthetic lubricants are exposed to the same amount of dirt and contamination, and the need to change lubricants is primarily to remove the dirt and contaminatioin. The long chain molecules of both standard and synthetic lubricants far outlast their ability to keep dirt in suspension. Some of these synthetic lubricants "fool" traditional testing by being very poor at keeping dirt in suspension. The purpose of a good engine or transmission lubricant (either kind) is to maintain dirt and contamination in suspension rather than letting it precipatate into what we call sludge. When in suspension the dirt is flushed out when you change your lubricant.

Most lubricants are changed much too often today. Consumer Reports did the best independent study on oils I have ever read (ignore oil manufacturer studies... they are biased). Read it and you will learn much about oil.

[SoCalDMAX]

csimo,

That was a great post! I do have a couple of questions for you. I understand that the synthetics last longer and withstand heat better; so you're saying not to extend the drain interval with a synthetic because of the contaminants which need to get flushed out? I agree, removing contaminants is the reason I change my oil rather than losing viscosity.

Would changing the Allison filter get these contaminants out and allow for the longer intervals that I was hoping for with Transynd?

When you quoted the CR study on oil, (I should go back and look for it) were they talking about engine oil or all lubricants?

What intervals were they saying was too often? I've often felt that 3,000mi was too often and depending on driving conditions 4,000 to 6,000mi was still providing good lubrication. As long as air filtration and ring seal was good, I would think outside contamination shouldn't be excessive.

Regards, Steve

[csimo]

Q: "Would changing the Allison filter get these contaminants out and allow for the longer intervals that I was hoping for with Transynd?"

A: The dirt and contaminates that a lubricant holds in suspension are much too small for your normal oil or transmission filter. Remember a transmission is not subjected to the same amount of dirt an engine is. A transmission is a sealed system and the only dirt it is subjected to is from the degredation of its own internal components. I don't know the specific fluid change interval GM recommends, but I would imagine that Transynd would last 50,000 miles or so after the initial breakin of the transmission.

Q: "When you quoted the CR study on oil, (I should go back and look for it) were they talking about engine oil or all lubricants?"

A: Their test was on engine oil.

Q: "What intervals were they saying was too often?"

A) The CR test (if memory serves me) was done on New York City taxis. Their test was for a total of over 4,000,000 miles! They replaced the engines in the taxis with identical engines (don't remember the details). They tore the engines down at the same number of miles (they checked them at 50,000 and took them out of service at 100,000 or something like that). They we unable to measure ANY difference between those that changed their oil at 3,000 miles, 5,000 miles, or 7,500 miles. No measurable difference. They did not test beyond 7,500 miles (again if memory serves) because they didn't want to exceed the manufacturers specs. of 7,500 mile oil changes. So to answer the question, it would seem that changing your oil sooner than the manufacturer requirement is a total waste of money. It would be hard to imagine any conditions more severe than a NYC taxi. This test was a few years ago, and motor oils have improved since then.

There are those who will argue till the end of time that 2,500 is the number, 3,000, 5,000, etc., but the only FACTS I know are that the manufacturer has specified the interval for a reason, and the non-oil company tests (CR is one of them) indicate that short drain intervals is nothing but a waste.

Detergent oils (most all on the market are) are designed to keep the non-filtered dirt and contamination in suspension. The main reason to change your oil is to flush out that suspended dirt and contamination with the old oil. The long chain molecules, and additives to any modern lubricant are still intact long after the recommended drain interval.

Some of these "cult style" synthetic oils, oil additives, etc. make crazy claims about pressure tests, ball tests, and a variety of other tests (they will never release the entire report that may show weakness in other catagories that are more important than pressure tests). Most of those tests have very little to do with real life engine requirements. They all make claims of "independent labratory tests", but when tested by a third party the results can't be reproduced. How many additives show cars running for hundreds of miles with no oil in the crankcase? When tested by Consumer Reports, 60 Minutes, 20/20 or other reputable sources the engines lock up in a few minutes. Why is that?

Hope this helps!

[ 06-15-2002: Message edited by: csimo ]

[ 06-15-2002: Message edited by: csimo ]</p>

[JEBar]

Csimo...the quality of your response is but one example of why so many of us really value this forum...many thanks for the information smile.gif

[mdrag]

JEBar,

Go to Allison's website:

www.allisontransmission.com

CLick on the PUBLICATIONS link just below the Allison logo. Then SEARCH BY PUBLICATION NUMBER and put in :

GN3465EN

The direct link is (cut and paste):

www.allisontransmission.com/publications/pubs/GN3465EN***p

Likely the forum software will edit the link - the last part after GN3465EN is -&gt; dot j s p without the spaces.

This is the Allison Approved oils list, approx 20 pages in pdf format, take your pick and choose your favorite flavor.

The last time I heard, Transynd synthetic was the only ATF approved for extended drain intervals (Amsoil is supposed to be working on getting approval). You can use other approved synthetic ATFs - such as Mobil 1 synthetic ATF - but should follow the normal maintenance schedule and not extended drain intervals.

Topic moved to 2500HD/3500 HD Trucks & Drivetrain Forum.

[ 06-15-2002: Message edited by: mdrag ]</p>