If you own a 2018 Ram 2500 or 3500 equipped with the 6.7L Cummins Turbo Diesel, keeping up with engine oil maintenance is one of the most important steps in preserving its power, fuel efficiency, and lifespan.
This guide explains the 2018 6.7 Cummins oil capacity, recommended oil type, change intervals, and tips to help you maintain top engine performance.
2018 6.7 Cummins Oil Capacity
The 2018 6.7 Cummins oil capacity is 12 quarts (11.4 liters) of engine oil when the oil filter is replaced. The recommended oil for this engine is 15W-40 for most climates or 5W-40 full synthetic for cold weather or maximum protection.
For best performance and longevity, the oil should be changed every 5,000–7,500 miles, depending on driving conditions such as towing, idling, and temperature. Regularly checking oil levels and using a high-quality oil filter helps ensure smooth operation and prevents engine wear.
Related Cummins Engine Oil Filters(Top 3 Best 2025)
Best Oil for 2018 6.7 Cummins
Click the Links Below to Check the Latest Prices on AMAZON
1) Shell Rotella T6 Full Synthetic 5W-40
- Full synthetic heavy-duty diesel engine oil.
- Excellent protection against wear, heat, and soot buildup.
- Performs well in cold starts and high-load towing conditions.
- Popular choice for year-round use in the 6.7 Cummins.
2) Valvoline Premium Blue Heavy Duty 15W-40 (Cummins Endorsed)
- Officially recommended by Cummins for the 6.7 engine.
- Designed for long engine life and stability under heavy workloads.
- Strong protection against thermal breakdown and oil oxidation.
- Great choice for towing, hauling, and hot-weather operation.
3) Mobil Delvac 1 ESP 5W-40 Full Synthetic
- Advanced full synthetic formula for extended performance.
- Provides excellent wear protection under severe duty cycles.
- Helps maintain cleaner pistons and reduces sludge formation.
- Ideal for trucks that run high mileage or frequent towing.
Related Cummins Engine Oil Capacity Chart(For All Models)
Recommended Oil Type for the 2018 6.7 Cummins
The factory-recommended viscosity for the 2018 6.7 Cummins is:
SAE 15W-40 for most climates
or
SAE 5W-40 Full Synthetic for cold temperatures or year-round stable protection.
Oil Change Interval
The standard oil change interval for a 2018 6.7 Cummins varies depending on driving conditions:
Diesel engines accumulate soot, and heavy-duty use can accelerate oil breakdown, so adjusting your oil change schedule to match your usage is essential.
How to Check the Oil Level
- Park on a level surface.
- Let the engine cool for 10–15 minutes after running.
- Remove the dipstick and wipe it clean.
- Reinsert fully, then pull it out again.
- Ensure the oil level is between the MIN and MAX marks.
If the oil is above the MAX line, drain some out. Overfilling can cause foaming and increased crankcase pressure, which may lead to damage.
Related Ram 2500 6.7 Cummins Oil Capacity(For All Model Years)
Symptoms of Running Low or Dirty Oil
- Louder engine noise or knocking
- Reduced acceleration or performance
- Higher operating temperatures
- Black exhaust smoke is becoming heavier
- Oil pressure warning light
Ignoring oil issues can cause serious engine wear or even failure, especially in a diesel work engine like the 6.7 Cummins.
Tips for Keeping Your 6.7 Cummins Running Strong
- Always use a high-quality oil filter, cheap filters can collapse or clog.
- Warm up the engine before towing or heavy hauling.
- Let the turbo cool down by idling 30–90 seconds before shutdown.
- Check oil levels more frequently if towing or driving off-road.
- Consider a bypass filtration system for extended engine life.
Related Cummins M11 Engine Oil Capacity Chart(For All Models)
FAQs
How much oil does a 6.7 Cummins take in 2018?
A 2018 6.7 Cummins takes 12 quarts (11.4 liters) of engine oil when the oil filter is replaced.
How much oil does a 6.7 L diesel take?
Most 6.7L diesel Cummins engines from Ram trucks require 12 quarts of oil with a filter change, though always confirm with the dipstick after filling.
Can you put 15W40 in a 6.7 Cummins?
Yes, 15W-40 is an approved and commonly recommended oil viscosity for the 6.7 Cummins, especially in warmer climates or heavy-duty towing conditions.
What oil does a 6.7 Cummins take in a RAM 2500?
A Ram 2500 with the 6.7 Cummins typically uses SAE 15W-40 or SAE 5W-40 full synthetic, depending on climate, usage, and performance preference.
How many quarts does a 2018 6.7 take?
The 2018 6.7 Cummins engine uses 12 quarts of oil with the oil filter changed.
Final Thoughts
The 2018 6.7 Cummins is built for strength, durability, and long service life, but only if maintained properly. Using the correct oil type, filling to the right capacity of 12 quarts, and sticking to regular oil change intervals can significantly extend engine performance and reliability.
Whether your Ram is a daily driver, a farm workhorse, or a hauler for heavy loads, giving your Cummins clean oil is the cheapest insurance you can provide.
