Severe service conditions apply to vehicles that are:
• Driven in dusty environments
• Frequently used to tow a trailer or haul material
• Idled for extensive periods
• Frequently driven in stop-and-go traffic
• Frequently driven for short trips or in a manner that prevents the engine from reaching normal operating temperature (particularly important in cold weather)
6.5L GM Diesel maintenance schedule
Service Procedure |
Recommended Interval |
Notes |
Replace air filter |
Inspect at every oil change and replace as necessary. Replace regardless @ 15,000 miles under severe service conditions. Replace regardless @ 30,000 miles under normal service conditions. |
Part number(s) available in service part/specs below. |
Change engine oil, replace oil filter |
Change engine oil and replace oil filter every 2,500 miles under severe service conditions, 5,000 miles under normal service conditions. |
7 quart capacity w/ filter through 1998 model year, 8 qts w/ filter capacity 1999+ model years. |
Replace fuel filter |
Replace fuel filter every 30,000 miles. |
GM recommends 30,000 mile fuel filter replacement intervals. However, more frequent fuel filter service is advised - consider replacing every other oil change, especially on older vehicles. |
Replace serpentine belt |
Inspect serpentine belt every oil change and replace as necessary. |
Replace belt when grooves are worn, belt begins to squeal, or belt exhibits cracking. |
Change automatic transmission fluid |
Replace transmission fluid and filter every 50,000 miles |
Capacity varies with application - refer to owners manual or fill to correct operating range per dipstick indicator. |
Change manual transmission fluid |
50,000 to 100,000 mile fluid replacement advised depending on conditions; frequent towing should result in more periodic service |
GM suggests the NV4500 manual transmission does not require service and is "filled for life". We recommend servicing the transmission periodically to maximize synchronizer life. Follow GM fluid spec - failure to use a compatible fluid will result in premature transmission damage. |
Change front differential fluid |
Replace differential fluid at 15,000 mile intervals |
General Motors 9.25" IFS differential, 1.83 qts fluid capacity |
Change rear differential fluid |
Replace differential fluid at 15,000 mile intervals, check fluid level at every oil change and add as necessary |
Capacity varies, always fill differential to fill plug level - see fluid spec breakdown below. More frequent differential service may be required on C3500HD chassis cab trucks with a Dana 80 axle. An additive may be required in limited slip differentials - refer to owners manual. |
Cooling system service |
Flush cooling system, replace upper/lower radiator hose and thermostat every 30,000 miles or 24 months |
Capacity varies by application and model year - refer to owners manual. |
Replace glow plugs |
Replace glow plugs and glow plug controller every 100,000 miles |
N/A |
Replace CDR valve |
Replace CDR valve every 60,000 miles |
Replace CDR valve hose if damaged, excessively soaked in engine oil, or is otherwise worn. |
Replace Harmonic Balancer: |
Replace harmonic balancer every 100,000 miles |
Harmonic balancers known to fail after 100,000 miles. Replacement interval is not a GM recommendation, but due to the frequency of failures it is the general consensus, not just our recommendation, to replace the harmonic balancer at 100,000 mile intervals. |
6.5L Diesel Service Part Numbers
Service parts and part numbers applicable to C/K pickups and select chassis cab trucks - part numbers may vary for alternative 6.5L diesel applications. Always verify part fitment with your parts retailer. Click on a p/n for pricing and additional information.
Part Description |
Part Number |
|
Engine Air Filter: |
1992 - 1996 |
|
1997 - 2000 w/o out high cap. filter |
||
1997 - 2000 w/ high cap. filter |
||
Engine Oil Filter: |
||
Fuel Filter: |
||
Fuel Filter Strainer: |
||
Fuel Filter Retainer Ring/Nut: |
||
Fuel Tank Strainer/Sock: |
ACDelco TS1012(in-tank sending unit filter) |
|
Serpentine Belt: |
w/ vac pump & AC |
|
w/ AC, w/o vac pump |
||
Alternator: |
1992 - 1995 (new, not reman) |
ACDelco 3351015 |
1996 - 2000 (new, not reman) |
ACDelco 331068 |
|
Starter Motor Assembly: |
ACDelco 3371002 (new, not reman) |
|
Glow Plug: |
||
Glow Plug Controller: |
All 1992 - 1993 MY |
|
1994+ MY w/ electronic injection, PMD |
||
CDR Valve: |
||
CDR Valve Hose/Elbow: |
||
Oil Pressure Sensor/Switch: |
||
Fuel Lift Pump: |
1992 - 1993 |
|
1994+ |
||
Thermostat: |
1992 - 1996 (195° F) |
|
1997 - 2000 (195° F) |
||
Thermostat Housing Gasket: |
||
Temperature Sender/Sensor: |
Gauge temp sensor, all years |
|
ECM temp sensor, 1994 - 2000 |
||
Upper Radiator Hose: |
1992 - 1995 |
|
1996 - 2000 |
||
Lower Radiator Hose: |
1992 - 1993 |
|
1995 - 2000 |
||
Radiator Cap: |
ACDelco 12R7 or ACDelco 12R7S (w/ safety relief) |
|
Rear Differential Gasket: |
GM 14 bolt |
|
Dana 70 |
||
Dana 80 (3500HD models) |
Dana Spicer RD51997 |
6.5L GM Diesel Fluid Specifications & Capacities
Component(s) |
Oil/Fluid Specification |
Capacity [1] |
|
Engine oil [2] |
Ambient temp > 0° F |
SAE 15W-40 (preferred) |
7 quarts w/ filter change (1992 - 1998 model year) 8 quarts w/ filter change (1999+ model year) |
Ambient temp > 32° F |
SAE 30W |
||
Ambient temp < 32° F |
SAE 10W-30 |
||
Engine coolant [3] |
1992 - 1995 model years |
50/50 ethylene glycol engine coolant, distilled water |
5.5 - 6.6 gallons |
1996+ model years |
50/50 GM DEX-COOL, distilled water |
||
Automatic transmission fluid |
GM 4L60E/4L65E, 4L70E, 4L80E/4L85E |
11.5 - 13.5 quarts total capacity |
|
Manual transmission fluid |
New Venture NV4500 |
75W-90 Castrol Syntorq LT or equivalent specification [5] |
4 quarts |
Hydraulic clutch fluid |
GM 12345347 |
--- |
|
Transfer case fluid |
New Process NP231, NP233 |
ACDelco DEXRON VI [4] |
1.25 quarts |
New Process NP241 |
2.3 quarts |
||
BorgWarner BW4401, BW4472 |
1.5 quarts |
||
BorgWarner BW4470 |
3.3 quarts |
||
Front differential |
AAM 8.25 |
75W-90 or 80W-90 GL-5 gear oil |
1.51 quarts |
AAM 9.25 |
1.82 quarts |
||
Rear Differential |
GM 8.6 (10 bolt) |
80W-90 GL-5 gear oil |
2.1 quarts |
GM 9.5 (14 bolt, semi-float) |
2.7 quarts |
||
GM 10.5 (14 bolt, full float) |
3.25 quarts |
||
Dana 80 (C3500HD only) |
75W-140 synthetic gear oil [6] |
4.2 quarts |
[1] Oil/fluid capacities are nominal - always fill to proper dipstick, fill plug, or indicator level. Fluid level should always be verified before and after driving vehicle.
[2] Engine block heater required in ambient temperatures below 0° F. GM recommends block heater operated minimum 8 hours before starting; use 10W-30 in such conditions.
[3] Recommend a quality extended life engine coolant (ELC) for all applications. DEX-COOL engine coolant has been the source of many cooling system problems. ELCs typically have a long service life with minimal required maintenance. Recommend Fleetguard CC2820 ELC (blue, 150,000+ mile service life, use with SCA/DCA Fleetguard DCA4) or Fleetguard CC36073 ELC (red, silicate free, 300,000+ mile service life).
[4] DEXRON VI supersedes original DEXRON II E and later automatic transmission fluid specifications. Transmission fluid capacity can vary considerably depending on model, options, and drive type (4 wheel drive vs. 2 wheel drive). Service capacity will be much lower than listed dry fill capacity.
[5] New Venture NV4500 transmission fluid specification is very specific and synchronizer damage will occur if one of the listed fluids is not used.
[6] C3500HD calls for 80W-90 GL-5 gear oil and 3,000 mile service intervals, OR 75W-140 full synthetic gear oil and 30,000 mile service intervals. Recommend full synthetic 75W-140 gear oil.