If you use the conventional Dex 6 (IMO) drain/change spin on filter every 25K miles.
Most change the spin on filter every 10-15K miles.
Now switch over to Allison Transynd fluid (or an Allison approved TES 295 fluid) & you can go 4 years or 100K miles (whichever comes 1st) for drain intervals.
The internal filter they say no need to change unless the trans is being rebuilt.
I use Allison Transynd fluid & follow the Allison drain intervals (4 years or 100K miles which ever comes 1st.)
I change the spin on filter every 10K miles, & internal filter every 100K miles.
2500HD SLE CC/SB 4x4 LMM
Edge Insight CTS,
Flo~Pro 4" DP back exhaust w/muffler & stock trumpet tip,
Resonator delete plug,
Alum. bleeder screw,
WIF sensor delete plug,
Fumoto oil drain valve,
Pacer LED cab lights,
GM dually light bar under tailgate,
Cobra 29 WXNWST
Wilson 2000 CB antenna,
GM chrome oval running boards,
Michelin M/S2 on PY0 wheels,
Rubber mud flaps,
Curt class IV hitch
Last edited by HD Dmax Machine; 10-20-2012 at 07:24 PM.