7.3L Power Stroke Oil Change Guide

7.3L Power Stroke Oil Change Procedures & Oil Selection Guide

Applicable mode years: 1994.5 - 2003 7.3L Power Stroke diesel (F-Series, Super Duty, Excursion)
Engine oil filter: Motorcraft FL-1995
Oil pan drain plug: Ford F6TZ-6730-AA
Oil fill cap: Motorcraft EC-743
Oil specification: See chart below
Recommended oil additive: Archoil AR9100 friction modifier


7.3l Power Stroke Oil Selection

Oil selection may seem like a rudimentary subject; all you need is a diesel rated oil of the correct viscosity, right? Correct, but there's a bigger subject matter to be addressed. For all intents and purposes, conventional motor oil is perfectly fine to use in a 7.3L Power Stroke. However, because of the engine's unique hydraulic unit injectors reliability and longevity will be improved by selecting a high quality synthetic engine oil. Synthetic oils are becoming an industry standard as they exhibit far superior properties than any comparable conventional oil - period.

The HEUI injection system on 7.3L and 6.0L Power Strokes uses highly pressurized (3,000+ psi) engine oil to create fuel pressures in excess of 25,000 psi through an intensification process in each individual injector (see how HEUI injectors work). This process places an incredible shear force on the engine oil, breaking it down more rapidly than what would occur in a traditional diesel injection system. As engine oil breaks down, it loses its properties as a lubrication and the degree of engine protection degrades. Synthetic oils are far more resilient to these forces.

In addition to mechanical forces, engine oil also must also overcome thermal breakdown and crankcase contamination. All these mechanisms contribute to engine oil breakdown. Fuel dilution is a serious but normal condition in which diesel fuel and combustion remnants enter the crankcase do to blowy, a form of cylinder leakage that occurs normally (to some degree) in every engine. Synthetic motor oil is also more resilient to this chemical contamination and thus will maintain its properties longer and provide a greater level of protection between oil changes.

Lastly, stiction is a serious, somewhat preventable concern in HEUI injectors. While an injector is a serviceable wear item that is expected to be replaced, injector life can be extended by using a high quality synthetic oil and a stiction-combating oil additive. In fact, stiction is responsible for many misfire conditions in HEUI injector systems. In a nutshell, stiction occurs do to carbon buildup in the injector spool valve (oil side of the injector) and prevents the solenoid from functioning properly when an injection event is commanded. Archoil AR9100 friction modifier comes highly recommended and has been proven to both cure and prevent stiction related injector problems. Although it increases the price of an oil change, even infrequent usage (every other oil change, for example) has its benefits. When used with a quality synthetic motor oil, injector life will be maximized.

In summary, conventional engine oils are becoming a relic of the past. You don't necessarily need to use a synthetic oil, but there are significant benefits. Every project vehicle that leaves the Diesel Hub shop is converted to Amsoil from bumper to bumper; differentials, engine oil, manual transmissions, and transfer cases. We typically stick with OEM transmission fluid, only because we don't buy in to the notion that an ATF can meet any OEM fluid specification to the same standards that an application specific ATF can. Amsoil has a tiered engine oil product line available in multiple viscosities. Their products are on the higher end of the market, but there's arguably not a more proficient, reputable name in the synthetic oil industry.

Amsoil heavy duty diesel oil

Amsoil Signature series diesel oil

Heavy Duty Synthetic 15W-40

Signature Series 15W-40

4X the wear protection than required by Detroit Diesel's scuffing test specifications, reduced oil consumption, greater resilience to mechanical, chemical, and thermal breakdown. Entirely compatible with emissions controlled engines.

6X the wear protection than required by Detroit Diesel's scuffing test specifications, greatly reduced oil consumption, greatest resilience to mechanical, chemical, and thermal breakdown. Entirely compatible with emissions controlled engines.

7.3L Power Stroke Oil Viscosity Specs

Ambient Temperature

Recommended Viscosity


> 10° F


Preferred viscosity for ambient temperatures > 30° F

-10 to 90° F


Preferred viscosity for ambient temperatures between -10 and 30° F

< 30° F


Recommend using engine block heater

< 0° F


Recommend using engine block heater

How to Change the Engine Oil in a 7.3L Power Stroke Diesel

Click any thumbnail to view fullsize, detailed image

oil drain pan

• Ensure that the vehicle is in park (auto) or in gear (manual) and that the parking brake is engaged.

• Place an oil drain pan with a minimum 15 quart capacity beneath the engine oil pan drain plug.

• Loosen the oil drain plug with the boxed end of a 3/4" wrench, then unthread by hand.

draining engine oil

• Allow the engine oil to drain, then replace the drain plug (do not overtighten, just snug). If the sealing washer on the drain plug is damaged or worn, it should be replaced. The correct part number is Ford F6TZ-6730-AA. There are cheaper drain plugs on the market - you get what you pay for.

• Remove the engine oil filter (passenger side between the frame rail and engine oil pan). If the filter is stubborn, as screw on oil filters often are, use an oil filter wrench or wrap a piece of emery cloth around the filter for added grip.

oil filter location

• Slowly fill the new oil filter with roughly 1/2 to 3/4 of a quart of clean engine oil (this step is optional, but always recommended on vertically mounted oil filters).

• Lubricate the oil filter gasket with clean motor oil.

• Install the new oil filter. Tighten by hand as much as possible, do not use a wrench or other aid to tighten the oil filter.

oil fill location

• Locate the engine oil fill cap on the passenger side valve cover. Remove the cap and fill the crankcase with 15 quarts minus what was added to the oil filter. Replace the oil fill cap.

• Verify that the oil drain plug is not leaking.

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

• Turn the engine off and allow vehicle to sit for 5 minutes. Verify proper oil level using the engine oil dipstick.

Amsoil engine oil and Archoil oil additive

This 7.3L Power Stroke is leaving the shop with 14.5 quarts of Amsoil 15W-40 synthetic motor oil and a 16 oz treatment of Archoil AR9100 friction modifier. In addition to extending HEUI injector life, Archoil's friction modifier can reverse stiction related injector problems and misfires.