6.6L Duramax Diesel Oil Change Guide

6.6L Duramax Oil Change Parts List

[1] Highly recommend OEM GM/ACDelco lube oil filter.
[2] Includes replacement gasket.
[3] Drain plug gasket available separately for 2018+ model years. For 2001 to 2017 model years, gasket only available with purchase of new drain plug.
[4] 2001 to 2016 model year oil fill caps are different styles, but cross-compatible between model years.

Drain Plug Types & Torque Values

Some 6.6L Duramax diesels were factory equipped with a crush washer type drain plug gasket. The head on these drain plugs accepts a 16 mm wrench/socket and the factory torque spec is 62 lb-ft. However, the current replacement drain plug from GM accepts a 13 mm wrench/socket and features an integrated rubber seal. The factory torque spec on this drain plug is 18 ft-lbs.

Because the crush washer type drain plugs require relatively high torque, we recommend upgrading to the new style drain plug featuring the rubber seal. If using a crush type gasket, we recommend tightening the drain plug snug, checking for leaks, and tightening as necessary. 62 lb-ft of torque is relatively high for oil pan threads, and this is likely what has prompted the updated style drain plug.

6.6L Duramax Oil Requirements and Recommendations

6.6L Duramax Oil Viscosity Chart

^[1] SAE 15W-40 engine oil is preferred in all instances when the ambient temperature is greater than 0° F.
^[2] SAE 5W-40 engine oil is required in instances when the ambient temperature is less than 0° F. Although it is acceptable in all ambient temperatures, it is not preferred over 15W-40 when ambient temperatures are above 0° F.
^[3] SAE 10W-30 engine oil is acceptable within the listed temperature range for 2001 to 2007 model years only. It is not listed as an acceptable viscosity grade for 2007.5 and later engines. 10W-30 is not preferred over 15W-40 nor 5W-40 in any instance.

6.6L Duramax Viscosity Selection

GM recommends a 15W-40 viscosity grade engine oil in all instances that the ambient temperature remains greater than 0° F. If the ambient temperature is below 0° F, a 5W-40 engine oil is required to maximize protection during cold starts and the engine warm-up period. Although 10W-30 engine oil is listed as acceptable in the 2001 to 2007 Duramax diesel supplements, it comes with no recommendations; it is acceptable in applicable model years, but not preferred in any instance. We highly recommend a quality synthetic engine oil, which provides greater resilience against oxidation, contamination (including fuel dilution and soot infiltration), and thermal breakdown in addition to superior flow characteristics and engine protection in sub-zero temperatures. Moreover, synthetic lubricants can significantly reduce fuel dilution and oil consumption rates, even in high mileage engines.

API Category Requirements for Duramax Diesels

2001 to 2007 model year engines require an API CI-4 or CH-4 engine oil, while later 2007.5 and newer engines require a API CJ-4 or CK-4 engine oil. All engines equipped with a diesel particulate filter (DPF) require a low ash engine oil meeting API CJ-4 or CK-4 specifications. Failure to use such lubricants will result in ash build-up in the DPF and a potentially expensive repair bill. Note that CJ-4 and CK-4 oil categories are backwards compatible, thus they supersede the old CI-4 and CH-4 specifications. Most modern diesel oils from popular brands will be listed as API CJ-4 or CK-4 compatible.

6.6L Duramax Engine Oil Recommendations

Diesel Hub recommends the following Amsoil products for Chevrolet and GMC vehicles equipped with the 6.6L Duramax diesel:

Amsoil Max Duty Signature Series 15W-40 diesel oil
Premium engine oil for maximum engine protection; use in ambient temps above 0° F.

Amsoil Max Duty Signature Series 5W-40 diesel oil
Premium cold weather oil for maximum engine protection; required in ambient temps below 0° F.

Amsoil synthetic engine oils offer:

• Superior protection against fuel dilution and oil consumption

• Low ash engine oil meets or exceeds all applicable API ratings, protects EGR and exhaust aftertreatment systems

• Superior resilience against thermal, mechanical, and chemical breakdown of engine oil

• Improved oil flow and engine protection in sub-zero temperatures and during cold starts

Amsoil is a leading manufacturer of synthetic oils and lubricants, including a line of engine oils engineered to meet the stringent demands specific to diesel engines.

6.6L Duramax Oil Change Procedures

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• Place a suitable container (minimum 10 quarts capacity) beneath the engine oil pan.

• If applicable, place a shop rag between the oil pan and skid pan to prevent spillage; engine oil will have a tendency to pool here and run off one of the corners, evading your drain pan.

• Loosen the engine oil fill cap to help the crankcase vent while the engine oil is draining.

• Remove the drain plug from the oil pan using a box end wrench or socket; do not break the drain plug loose using an open end wrench. Drain plug sizes will vary, but genuine GM drain plugs are metric sizes.

• Locate the oil filter on the driver side of the engine (above the front driveshaft on 4 wheel drive vehicles).

• Remove the oil filter by unthreading it from the oil filter base. If the filter is stubborn, use an oil filter wrench or wrap a piece of sandpaper around the circumference to prevent your hand from slipping.

• Once removed, verify that the oil filter gasket did not stick to the base and thoroughly clean the mounting surface with a clean, lint free cloth or shop rag.

• Verify that the engine oil has drained completely from the oil pan.

• Inspect the oil pan drain plug for wear or damage, paying close attention to the gasket/o-ring. If damaged or otherwise compromised, replace the drain plug.

• Reinstall the engine oil pan drain plug and torque to the applicable specification outlined in the section above.

• Clean any residual oil around the drain plug so that leaks can be easily detected.

• Lubricate the gasket on the new oil filter with clean engine oil. Since the oil filter is mounted horizontally on these engines, it is impractical to pre-fill the new oil filter and therefore it must be installed dry.

• Install the new oil filter snug by hand; do not attempt to tighten the filter with tools.

• Add 10 quarts of new engine oil through the oil fill tube located at the front, center of the engine compartment.

• Verify the oil level using the engine oil dipstick located on the passenger side of the engine (in front of the fuel filter housing).

• Start the engine and check for leaks around the oil pan drain plug and oil filter housing.