The Allison 1000 uses an internal filter AND an external spin-on. Both need service. Skip either and you cook the clutches. Here is the right interval and procedure.
Allison 1000 filter locations
Internal filter:
- Inside the pan
- Suction-side filter
- Catches debris before pump
- Bolt-on plastic housing
External spin-on filter:
- Mounted on driver-side rear of trans
- Charge-side filter
- Catches debris before clutches
- Common point of confusion (often missed)
Service interval
OEM Allison recommendation:
- Internal filter: every 50,000 miles
- External spin-on: every 25,000 miles
- Both: every 100,000 miles minimum
HD towing schedule:
- Internal: 30,000 miles
- External: 15,000-20,000 miles
- Both: 50,000 miles
Tuned Duramax schedule:
- Internal: 25,000 miles
- External: 15,000 miles
- Critical to prevent clutch failure
OEM filter part numbers
Internal filter:
- AC Delco TF-280 (early)
- AC Delco 29545779 (later)
- $25-$45 part
External spin-on:
- AC Delco TP-1063 (early)
- AC Delco 25010792 (later)
- $15-$30 part
Fluid:
- TES-295 spec only (no Dexron)
- 15+ quarts for full service
- $200-$400 worth
Service procedure
Drain:
- Remove drain plug under pan
- ~12 qts come out (pan only)
- ~18 qts come out if external filter also drained
External filter:
- Spin off old filter (oil filter wrench)
- Lube new filter gasket with TES-295
- Spin on hand-tight, then 3/4 turn
Internal filter:
- Drop pan (16 bolts)
- Filter unbolts from valve body
- Replace pan gasket (cork or rubber)
- Torque pan bolts 89 in-lb cross pattern
Fill:
- 15+ qts TES-295
- Through dipstick tube or fill port
- Check level cold first
- Recheck at operating temp (180F)
Cost
DIY full service:
- Internal filter: $25-$45
- External filter: $15-$30
- TES-295 fluid (18 qts): $250-$400
- Pan gasket: $10-$25
- Total: $300-$500
Shop service:
- Parts: $300-$500
- Labor: $250-$400
- Total: $550-$900
What happens if you skip filter service
- External clogs first (visible from pressure drop)
- Internal clogs second (slipping under load)
- Slipping cooks clutches
- Cooked clutches require $4,000+ rebuild
Never substitute fluid
- TES-295 only
- NOT Dexron VI
- NOT generic synthetic
- Wrong fluid = clutch failure in 5,000-15,000 miles
Need Allison 1000 filters, TES-295 fluid, or rebuild parts? Shop our Allison catalog. OEM filters, TES-295 fluid, complete rebuild kits. Free shipping over $70.
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