2001 Allison 5-spd Auto maintenance question

[jocko]

Good evening truckers, I've got a basic question on fluid changes for the 2001 Allison 5 speed automatic (mine is behind an 8.1L). The owners and maintenance manuals call for fluid/filter service every 25k mi (for heavy use) and 50k mi (for regular use). As you know, the Allison has an internal filter and an external spin-on filter. Somewhere along the way I got the impression that it was appropriate to change the spin-on every 10-15k mi. Two questions have come up -

1) Why? I can't find any GM documentation that outlines changing the spin-on filter (only) at a lesser interval than the full fluid/filter service interval. Does anyone have any GM or Allision documentation that outlines whether/when to change the spin-on filter only?

2) IF it should be changed at lesser intervals - should the pan be drained when doing "just" the spin-on filter replacement? I would assume "yes" - but after consulting Dr. Youtube, only 1 of about 10-15 different vids on this topic demonstrate also draining the pan. It's a big difference in amount of fluid to replace in the system (and therefore, cost). It's only a few ounces of fluid to replace the spin-on filter but it's 6-7 quarts to replace the spin-on filter AND drain the pan. But the latter certainly makes a lot more sense to me - IF, that is, it's required at all. I've scoured the owners manual and the full set of GM service manuals and ATSG Allison 1000 manual with no luck (or I just missed it). The service manuals DO reference two different fluid replacement levels (7.4 qt for a fluid change or 12.7 for overhaul - i.e. accounting for diff in lines, cooler, and converter, etc) but only one service interval, so it's a little confusing. It never calls out doing "just" the spin-on filter - although it references the fluid change only amount. I noted that I only drained about 6 quarts when I changed the spin-on and drained the pan, so that's what I replaced and then did the hot trans level checks to top it off correctly. But I would like to get my arms around whether this is necessary. Of course it's better than not doing it - but given the look of the fluid I drained out after 12k mi, I highly doubt it was necessary at all.

Any insight appreciated, thank you.

[hatzie]

I would change the spin-on filter and de-fuzz the magnet every other engine oil change. I do with my Magnefine on my 4L80E and my 4T65E-HD on that interval.
It won't hurt a thing and that filter really isn't super expensive or difficult to service. The $12 Allison filter is lots cheaper than the Magnefine inline filter.

The magnet recess in a small spin-on hydraulic filter along with the reasonable price gives me thoughts about machining a filter base for the Allison/Saturn spin on filters to install one of them in transmission cooler return lines rather than using the inline filters.

You're already under there to do the engine oil so it's not a big deal. Wipe off the ring magnet and put it back with the new filter and top off the fluid with the couple oz you wasted from the filter or just pre-fill the filter with ATF.

[jocko]

Thx Hatzie, appreciate the input. I may go with the following based on what I've seen so far:
- spin-on (only, without pan drain) every 12.5K
- spin-on (with pan drain) every 25K
- spin-on, pan drain, and internal trans filter every 50K per the manual

With the 25K service, I'll check the fluid to see how it looks, and maybe skip this in the future, it is still likely overkill.

Thanks again!

[hatzie]

Originally Posted by jocko

Thx Hatzie, appreciate the input. I may go with the following based on what I've seen so far:
- spin-on (only, without pan drain) every 12.5K
- spin-on (with pan drain) every 25K
- spin-on, pan drain, and internal trans filter every 50K per the manual

With the 25K service, I'll check the fluid to see how it looks, and maybe skip this in the future, it is still likely overkill.

Thanks again!

Sounds like a plan. That's mostly what preventive maintenance is.
Changing the fluids is cheaper than overhauls.

I read an article back in the late 1980's where they did an actual real world test on a handful of NYC taxi cabs. 3K, 5K, 7.5K, & 10K oil changes for 100K miles IIRC but it might've been 200K. They did lab tests on the oil. The wear metals had started to rise slightly toward the end in the 7.5K and 10K groups but the engine teardowns showed insignificant cylinder, piston, and bearing wear after 100,000 miles for all four groups.
I use the 5K and 5K multiple intervals because they're easy to remember and seem to be soon enough.

[jocko]

thanks again Hatzie, that's good info I like the 5K interval/multiple approach - I do wish the factory made a simple chart in the owners manuals - the goofy way they spell it out at each weird interval seems more confusing to me, so I make my own chart. I'd say most of us on this site are light years ahead of the rest of the general public for being pretty picky about our PM, ha. I'm probably too picky, but I'm ok with that.

[biketopia]

I know this is a two week late response, but when I had my 03 duramax I would do the external filter every 10k, drain and fill the pan every 25k, why my truck was used it was used hard. At the time, all the Allison documents I had and speaking with the Allison dealers they all said the internal filter should only be replaced at a rebuild. I did mine at 100k just for the hell of it but then was doing regular drain and fills with the external filter and never thought twice about dropping the pan again. Use the correct TES 295 approved fluid! Unless your trans has been built, then some builders recommend a Dex3, otherwise stick with approved fluid. Also make sure you remember the magnet, when I did the first external filter when I got my truck with 72k on it the magnet was gone...

[jocko]

Thanks for the reply biketopia, appreciate the input. My trans is bone stock, never apart. All my 2001 GM service manuals state Dex III for it originally, which has subsequently been superseded by Dex VI per TSB, so that's what I've been using.

[hatzie]

Originally Posted by biketopia

I know this is a two week late response, but when I had my 03 duramax I would do the external filter every 10k, drain and fill the pan every 25k, why my truck was used it was used hard. At the time, all the Allison documents I had and speaking with the Allison dealers they all said the internal filter should only be replaced at a rebuild. I did mine at 100k just for the hell of it but then was doing regular drain and fills with the external filter and never thought twice about dropping the pan again. Use the correct TES 295 approved fluid! Unless your trans has been built, then some builders recommend a Dex3, otherwise stick with approved fluid. Also make sure you remember the magnet, when I did the first external filter when I got my truck with 72k on it the magnet was gone...

It came off the line with GM Dexron III in it.
The 2006 trucks came off the line with Dexron VI in them.

Apparently GM recommends Allison Transynd TES 295 for temps below -40° ambient so it does work and it won't hurt the Allison 1000 to run it if you can handle the price.

The below dieselplace thread recommends the TES 295 rather than Dexron VI

TES 389 is supposed to be exactly the same as the old Dexron III H. Chevron makes it as ATF HD 389.

There's a bunch of Dexron VI might do this or that bad thing in this thread. It might, but GM used it and I can't find a TSB warning to not use Dex VI so I'd want to do a bit more research before I take somebody's word for it.
https://www.dieselplace.com/threads/...ansynd.318081/

More arguments on BITOG. https://bobistheoilguy.com/forums/th...dex-vi.159697/

Kinda like the religious wars over "my engine oil is better".

If it was my truck I'd run the Dexron VI in it, change the spin-on filter every other engine oil change, and change the fluid at 2x the spin on filter interval and not worry about it.

[jocko]

Thanks Hatzie!

[biketopia]

I used the 295 fluid because I was able to get our bulk jobber pricing though work.