2015 Peterbilt 389 Oil Capacity & Filter Reference

The 2015 Peterbilt 389 requires an oil capacity of 11 gallons (41.6L) for the PACCAR MX-13 engine and 12 gallons (45.4L) for the Cummins ISX15. Always verify the oil level on the dipstick after filling.

Quick Answer

• Oil Capacity (PACCAR MX-13): 11 gallons / 41.6 Liters (with filter)
• Oil Capacity (Cummins ISX15): 12 gallons / 45.4 Liters (with filter)
• Recommended Oil Weight: 15W-40 or 5W-40 Synthetic
• Oil Specification: API CK-4 / CJ-4
• PACCAR MX-13 Oil Filter: OEM P/N 1873016PE. Aftermarket: WIX 57791, Fleetguard LF16165.
• Cummins ISX15 Oil Filter: OEM P/N 4367341. Aftermarket: WIX 57746XD, Fleetguard LF14000NN, Mobil 1 M1-601.

Capacity by Engine Option

Oil Change Interval

The oil change interval for a 2015 Peterbilt 389 depends heavily on the engine and its duty cycle. Modern engine monitoring systems will often calculate the ideal oil change interval. Always consult your owner's manual for the most precise recommendations.

• Normal Duty: For trucks running in standard, over-the-road conditions, an interval of 25,000 to 50,000 miles is common, depending on the engine's oil monitoring system and the type of oil used (conventional vs. synthetic).
• Severe Duty: For trucks involved in vocational applications (construction, logging, heavy-haul) or that spend significant time idling, a shorter interval of 15,000 to 25,000 miles is recommended to protect the engine from increased wear.

Drain Plug Torque

Proper torque on the drain plug is critical to prevent leaks and damage to the oil pan.

• Drain Plug Torque: 60-65 lb-ft (81-88 Nm).
• Crush Washer: Always use a new crush washer with every oil change to ensure a proper seal.

How to Change the Oil (Simplified)

Changing the oil on a Class 8 truck is a more involved process than on a passenger car due to the massive fluid volumes.

1. Warm Up: Run the engine for 5-10 minutes to warm the oil.
2. Position & Drain: Park on a level surface. Position a large-capacity oil drain pan (at least 15 gallons) under the oil pan drain plug. Remove the plug and allow the oil to drain completely, which can take 20-30 minutes.
3. Replace Filters: While the oil drains, locate and replace the oil filters. Clean the mounting surfaces and lightly lubricate the new filter gaskets with fresh oil before installation.
4. Replace Plug: Clean the drain plug, install a new crush washer, and torque the plug to 60-65 lb-ft.
5. Fill with Oil: Fill the engine with 11-12 gallons of the correct specification oil. Start by adding slightly less than the full capacity.
6. Check Level: Start the engine and let it run for a few minutes to circulate the new oil. Shut it down, wait 10-15 minutes for the oil to settle, and then check the dipstick. Add oil as necessary to reach the "Full" mark.

Common Issues & Tips

• Engine-Specific Filters: The PACCAR MX-13 and Cummins ISX15 use different oil filters. They are not interchangeable. Using the wrong filter can lead to catastrophic engine damage.
• Synthetic Oil Benefits: While more expensive, using a 5W-40 synthetic oil can provide better cold-start protection and improved fuel economy, especially in colder climates.
• Oil Analysis: For fleet vehicles, consider using an oil analysis service. Sending a sample of used oil to a lab can identify potential engine problems like coolant leaks or excessive wear metals long before they become major failures.
• Filter Pre-Filing: There is much debate on pre-filling large oil filters. The primary risk is introducing unfiltered oil or contaminants into the new filter. The recommended practice by most engine manufacturers, including Cummins, is to install the filters dry to avoid this risk. The engine's oil pump is designed to prime the system quickly.

Need an oil change? Find a trusted shop on Repairius.