2018 Ram 1500 5.7 Oil Capacity [2026]

For the 2018 Ram 1500, the 5.7L HEMI V8 stands as a benchmark of American engineering, but its longevity is strictly dependent on precise lubrication management. While this engine is renowned for its durability and “Hemi” power delivery, it is also a sophisticated piece of machinery utilizing advanced hydraulic systems that are sensitive to oil volume and viscosity. Owners often face conflicting information regarding the exact oil capacity and the specific viscosity requirements needed to satisfy the sensitive Multi-Displacement System (MDS). This expert guide provides the definitive 2018 Ram 1500 5.7 oil capacity, technical specifications for fluids and filters, and a professional-grade maintenance procedure to ensure your truck remains a reliable asset for years to come.

Determining the 2018 Ram 1500 5.7L HEMI V8 Engine Oil Capacity

Precision is the hallmark of professional engine maintenance. When servicing the 5.7L HEMI V8 in a 2018 Ram 1500, the official manufacturer-specified service fill volume is exactly 7.0 quarts (6.6 liters) including the filter change. In my 15 years of industry experience, I have seen numerous instances where technicians mistakenly assume a “standard” 5-quart or 6-quart fill. In the HEMI, being even one quart low can lead to increased oil temperatures and potential aeration of the fluid.

This 7-quart capacity is not an arbitrary number; it is critical for the Multi-Displacement System (MDS). The MDS uses oil pressure to activate and deactivate lifters, allowing the engine to switch between 4-cylinder and 8-cylinder modes for fuel efficiency. If the oil level is incorrect, the hydraulic pressure required to toggle these solenoids can fluctuate, leading to rough transitions or stored trouble codes (DTCs). Furthermore, the 5.7L engine utilizes a “wet sump” design where the oil pan acts as the primary reservoir. Whether your 2018 Ram is a 2WD or 4WD configuration, the internal engine components and oil pan volume remain identical, requiring the same 7-quart volume.

To verify the level professionally, always perform a dipstick check after the engine has reached operating temperature and then sat for at least five minutes on a level surface. The oil level should fall within the cross-hatched “Safe” zone. In my practice, I recommend filling 6.5 quarts, running the engine briefly to circulate oil through the filter, then topping off the final 0.5 quarts to reach the exact “Full” mark. This prevents accidental overfill due to residual oil in the upper valvetrain.

Recommended Oil Viscosity and Quality Standards for Reliable Performance

The choice of engine oil for the 5.7L HEMI is a matter of engineering necessity, not personal preference. Fiat Chrysler Automobiles (FCA) mandates the use of SAE 5W-20 engine oil. The lighter viscosity is essential for the tight tolerances of the MDS solenoids. Using a heavier oil, such as 10W-30 or 20W-50, is a common pitfall that can cause the MDS to malfunction, resulting in a “Check Engine” light and decreased fuel economy. The professional standard dictates that even if you live in a hot climate, the 5W-20 grade should be maintained to ensure proper lubrication of the overhead cam and lifter assemblies.

Quality standards are equally vital. The oil must meet the Chrysler Material Standard MS-6395. This is a rigorous engineering specification that ensures the oil can withstand the high thermal loads of a V8 engine while maintaining chemical stability over a long service interval. Many generic “off-the-shelf” oils do not meet this standard. Using a non-compliant oil can technically void your powertrain warranty and may contribute to the infamous “Hemi Tick”—a noise often caused by inadequate lubrication of the roller lifters.

Full synthetic oil is the professional’s choice for the 2018 Ram 1500. While conventional oil is technically permitted if it meets MS-6395, synthetics offer superior shear stability and cold-flow properties. In cold-start scenarios, synthetic 5W-20 reaches the top of the engine significantly faster than conventional oil, reducing wear on the camshaft lobes. This is the most complete way to ensure your HEMI reaches high mileage without significant internal wear.

Selecting Professional Grade Oil Filters and Hardware

An oil change is only as effective as the filtration system accompanying it. For the 2018 model year, the Mopar MO-339 is the original equipment (OE) filter. This filter is engineered with a 22mm x 1.5mm thread pitch and is specifically designed to handle the high flow rates of the 5.7L V8. One of the most overlooked features of a high-quality filter is the anti-drainback valve. In the HEMI’s overhead valve configuration, a reliable silicone anti-drainback valve prevents oil from draining out of the filter and back into the pan when the engine is off. This ensures that oil pressure is available immediately upon startup, preventing “dry starts” that lead to premature bearing wear.

From a professional standpoint, I often see “budget” filters fail during cold weather. If a filter lacks a properly calibrated internal bypass valve, the thick oil during a cold start may be restricted, forcing the bypass valve to open and allow unfiltered oil into the engine. Premium aftermarket options such as the Wix 57060XP or the Fram Endurance FE10060 provide synthetic glass-fiber media that offers superior efficiency (often 99% at 20 microns) compared to standard cellulose filters.

Addressing High-Mileage Maintenance and Severe Service Intervals

While the official manual suggests oil change intervals can extend up to 10,000 miles or 12 months, professional mechanics understand that real-world conditions often fall under the “Severe Service” category. If you use your 2018 Ram 1500 for frequent towing, off-road driving, or extended idling (typical for job sites), your oil degrades much faster. In these scenarios, the oil is subjected to higher oxidation and fuel dilution. For a reliable, long-lasting HEMI, I recommend reducing the interval to 5,000 miles or 6 months.

For high-mileage engines (those surpassing 100,000 miles), monitoring oil consumption becomes a critical part of your maintenance guide. It is common for older HEMI engines to consume a small amount of oil between services. Checking your dipstick every 1,000 miles is a professional habit that prevents the level from dropping below the 7-quart requirement, which is the most frequent cause of lifter failure. If you are concerned about internal wear, consider an oil analysis program through a lab like Blackstone Labs. This provides a comprehensive view of wear metals like copper, lead, and iron, acting as an early warning system for your engine’s health.

Finally, a note on additives: In my professional experience, if you are using a trusted, high-quality full synthetic oil that meets MS-6395, additives are generally unnecessary and can sometimes interfere with the oil’s carefully balanced chemistry. The best “additive” for a 5.7L HEMI is simply clean, fresh oil at the correct volume. I have seen fleet trucks reach over 300,000 miles solely by adhering to 5,000-mile synthetic oil change intervals, proving that consistency is the ultimate key to engine longevity.

The 2018 Ram 1500 5.7L HEMI requires exactly 7.0 quarts of SAE 5W-20 oil meeting MS-6395 standards. Utilizing a high-quality filter like the Mopar MO-339 is essential for protecting the MDS and lifter assemblies. Regular monitoring of oil levels and adjusting service intervals based on driving conditions ensures long-term engine reliability. Ensure your next oil service uses only certified full synthetic fluids to maintain the professional performance of your HEMI engine.