Community Forums

716OutWest · 03-31-2023, 06:52 AM

Hello,
I bought a 2006 Monaco Diplomat (Cummins 400 / Allison 3000) 1 year ago. It was a 2 owner coach that was very well taken care of (overall) with all service records. I have put ~7000 miles on the coach in the past 12 months doing a cross country trip with no issues. Just finished doing all the annual maintenance myself (oil change, lube, fuel filter changes, generator service, etc.).

MY DILEMNA: I noticed that the Allison transmission has not been serviced since 2006 when the initial 5,000 mile filter change was performed. The coach now has ~146K miles on it and likely still has the original Dexron trans fluid / filters. The transmission has run fine with no issues and after research I have come across all kinds of opinions (leave it alone Allison's are indestructible, change fluid to Transynd and change filters, change filters only, etc.). I know I am going to get different opinions but I am getting ready to bring the family cross country again and not sure if I should do the full service or leave it alone. I know sometimes when you change that old of trans fluid it can start to clean out all the old gunk and cause issue.

Thank you to all for any recommendations / advice!

-716OutWest

wolfe10 · 03-31-2023, 06:57 AM

Absolutely, do a filter and fluid change.

From any Allison dealer, get the filter kit which will come with both filters and all needed seals.

Buy a 5 gallon pail of TS668-- Allison's current generation (and completely backwards compatible) fluid. That will leave you with one quart left over from the change.

Be sure to use an inch-lb torque wrench on the filter cover bolts.

Very easy DYI job.

jacwjames · 03-31-2023, 07:10 AM

I would do an oil & filter change. The original oil was probably Transynd, that was the recommended oil at the time. The new oil TS688 as mentioned in the previous post is what you want to use. I live near an Allison shop and buy it there, not a bad price.

I did an oil/filter change and then a follow up filter change twice in the last 10 years. Not hard.

Scepter40 · 03-31-2023, 08:26 AM

Ugh, this in on my list as well. Doesn't seem to be a hard job, I'm just being lazy about it. I'm at the 75K service interval now.

ArtJoyce · 03-31-2023, 08:35 AM

Quote:

Originally Posted by jacwjames

I would do an oil & filter change. The original oil was probably Transynd, that was the recommended oil at the time. The new oil TS688 as mentioned in the previous post is what you want to use. I live near an Allison shop and buy it there, not a bad price.

I did an oil/filter change and then a follow up filter change twice in the last 10 years. Not hard.

Yep you are over due. You should have the transynd -295 in it which called for evey 5 years to be changed. The new oil to use is the transynd-688 with is compatable with the 295. You should get the filter set for Alison they have had changes in the filter design since 2006 and they will supply the latest filter. the 3060 transmission had two pans a 2 inch and 4 inch. 99% of the 3000 transmissions in MH's are the 2 inch pan which you will drop about 17 quarts in a drain and filter.

PS: before calling the Allison shop, get the model number and SN off the transmission.

Winemaker2 · 03-31-2023, 09:26 AM

Agree... change to 668 for sure.
You need to figure out which pan you have but a direct measurement can be confusing as they are not exactly 2" or 4". A search online should provide the details or as recommended get tranny M/N & S/N to be sure and you'll have it for future reference. Exact fill reqmts avail online.

wolfe10 · 03-31-2023, 09:32 AM

On the driver's side of the transmission is a small metal plaque with model and serial number. Safest to get parts using your specific model/serial number.

Alpine36 · 03-31-2023, 09:44 AM

All the information and advice above is correct.
If DIY, just remember cleanliness is next to godliness when it comes to transmission servicing. Take your time, be super clean, no paper towels on anything internal. Brakleen everything including your funnel before re assembly.
Easy DIY project.

jacwjames · 03-31-2023, 09:59 AM

One thing I've been doing for the last 5 years is doing oil anlysis on both the engine and transmission. Last oil change I pulled a sample just to know the condition. Next tran oil change I'll probably do another sample.

I buy 3 kits at a time from JG Lubrication, turn around time is pretty quick. Worth the piece of mind for the $$$

Gary RVRoamer · 03-31-2023, 10:29 AM

Quote:

Originally Posted by 716OutWest

Hello,

MY DILEMNA: I noticed that the Allison transmission has not been serviced since 2006 when the initial 5,000 mile filter change was performed. The coach now has ~146K miles on it and likely still has the original Dexron trans fluid / filters. The transmission has run fine with no issues and after research I have come across all kinds of opinions (leave it alone Allison's are indestructible, change fluid to Transynd and change filters, change filters only, etc.). I know I am going to get different opinions but I am getting ready to bring the family cross country again and not sure if I should do the full service or leave it alone. I know sometimes when you change that old of trans fluid it can start to clean out all the old gunk and cause issue.

Thank you to all for any recommendations / advice!

-716OutWest

In a 2006 the original factory tranny fluid fill would have been Transynd, not Dexron. Allison has been shipping trannys with Transynd since early 2002 and chassis builders changed over to it soon thereafter (after they used up their stocks of Dexron). Surely Roadmaster did the same.

I'd change fluid and filters as soon as convenient. No worries about it.

Tha_Rooster · 03-31-2023, 03:39 PM

Quote:

Originally Posted by 716OutWest

Hello,

I bought a 2006 Monaco Diplomat (Cummins 400 / Allison 3000) 1 year ago. It was a 2 owner coach that was very well taken care of (overall) with all service records. I have put ~7000 miles on the coach in the past 12 months doing a cross country trip with no issues. Just finished doing all the annual maintenance myself (oil change, lube, fuel filter changes, generator service, etc.).

MY DILEMNA: I noticed that the Allison transmission has not been serviced since 2006 when the initial 5,000 mile filter change was performed. The coach now has ~146K miles on it and likely still has the original Dexron trans fluid / filters. The transmission has run fine with no issues and after research I have come across all kinds of opinions (leave it alone Allison's are indestructible, change fluid to Transynd and change filters, change filters only, etc.). I know I am going to get different opinions but I am getting ready to bring the family cross country again and not sure if I should do the full service or leave it alone. I know sometimes when you change that old of trans fluid it can start to clean out all the old gunk and cause issue.

Thank you to all for any recommendations / advice!

-716OutWest

Just a comment changing is not hard, the transmission hosing is aluminum so be careful scrapping off gasket. Also you will need a torque wrench to tighten to specs.

n2zon · 03-31-2023, 03:47 PM

Assuming it's filled with Transynd, I'd change the filters and have the fluid tested, changing it only if the testing results pointed that way. But that's just me...

Cat320 · 03-31-2023, 06:12 PM

Quote:

Originally Posted by n2zon

Assuming it's filled with Transynd, I'd change the filters and have the fluid tested, changing it only if the testing results pointed that way. But that's just me...

As long as the fluid tests good, it is good and no change required.

As mentioned in an earlier post, I too use J. G. Lub yearly.

wolfe10 · 03-31-2023, 06:23 PM

Quote:

Originally Posted by n2zon

Assuming it's filled with Transynd, I'd change the filters and have the fluid tested, changing it only if the testing results pointed that way. But that's just me...

Sorry, but I have to disagree.

At 17 years and 146,000 miles, it NEEDS to be changed. PERIOD.

Fluid and filters are cheap-- transmissions, not so much.