Transmission service interval?

Mike in GA · February 19, 2017, 01:58:54 PM

At a recent Bus Nuts rally in Ocala FL (25 coaches) it was mentioned regarding our Allison 740 and 755 transmissions that the maximum length of time between trans oil and filter changes was three years, regardless of mileage.
I thought as long as the fluid was bright red it could go a much longer time. Any thoughts?
Mike in Ga

eagle19952 · February 19, 2017, 03:26:17 PM

Quote from: Mike in GA on February 19, 2017, 01:58:54 PM
At a recent Bus Nuts rally in Ocala FL (25 coaches) it was mentioned regarding our Allison 740 and 755 transmissions that the maximum length of time between trans oil and filter changes was three years, regardless of mileage.
I thought as long as the fluid was bright red it could go a much longer time. Any thoughts?
Mike in Ga

I know of lots of Allison transmissions that have gone much longer...not further...that have suffered zero.

And I have seen 55 gal. drums stored longer...

My thoughts on some maintenance intervals differ. Having been to many oil jobber conferences and product seminars, (brand un-named but blue bottles and barrels.. ) I have formed many of my own opinions. oil has been underground for longer.

Mike in GA · February 20, 2017, 05:20:27 AM

I think the filter was the chief concern - not going much past 3 years before deteriorating, etc.
Mike in Ga

daddysgirl · February 20, 2017, 05:29:06 AM

I have to default to what dad always said (Fleet manager for 40 years who assumed ALL drivers of his fleet were total idiots). Notwithstanding Mikes good point...
If the fluid (didn't matter which) does not smell burnt, or look used, leave a good gasket alone.
Now that didn't mean forever, but he had his own timing for fluid (and tire) changes.

luvrbus · February 20, 2017, 05:58:55 AM

Depends on what fluid you use and the mileage,change the filter at least once a year,the chemical coatings on the filter are not permanent on the media.
When the chemical coatings are gone they lose their effectiveness to filter then it builds up on the 2 filters inside the transmission.Pull a sample on the fluid with the filter change.No offense but the smell and color is not going to tell you much, a sample will tell you lol I have rebuilt the 740's before that had the nice odorless with good color fluid.Me personally I wouldn't run the fluid for 3 years either that transmission circulates the 10 gals many times in 1 hour of driving

daddysgirl · February 20, 2017, 06:09:18 AM

Dads rules did involve a sample...and after thinking about all the invoices, the transmission was the exception. My bad.
He changed it yearly. OK. I feel like a dumb bunny now

PP · February 20, 2017, 11:15:40 AM

I'm kind of curious what most people are running in their Allison's for fluid. I remember a long while back this came up and I noticed that a lot use straight weight motor oil (non-detergent). Is that still the case? Or has sentiment changed?

Melbo · February 20, 2017, 05:48:12 PM

I have a ZF. I know that is a different animal than is being discussed here BUT the man who rebuilt my transmission told me to change the oil and filter annually no matter how little it was driven. He said and I quote "oil and filter are the cheapest thing you will ever put into your transmission." When I paid the bill for the rebuild I knew what he was saying. I have changed the oil annually since then.

Melbo

PP · February 20, 2017, 06:04:17 PM

I don't change the fluid as often as I should, but the bus came with a bay full of new parts that included half dozen filters for the trans so I change the filter regularly based on miles driven and not time frame so much. I've gone through most of the fuel filters already and am considering replacing the fan drive belt this summer and keeping the old one for a backup since I have a new one of them also.

DoubleEagle · February 21, 2017, 02:29:45 PM

Quote from: PP on February 20, 2017, 11:15:40 AM
I'm kind of curious what most people are running in their Allison's for fluid. I remember a long while back this came up and I noticed that a lot use straight weight motor oil (non-detergent). Is that still the case? Or has sentiment changed?

That subject comes up often. Cliff states often that 740 Allison's love 15-40 oil (meeting Allison Specs). Others like Transynd or other brand equivalents of synthetics. Which model of Allison you have can make a difference, but the main thing is change it and the filter(s) based on time & miles. Typical conversion use dictates that time is the deciding factor, and the benefits of synthetic over conventional take many miles to see, if ever.