Although the 6.4L Powerstroke is a powerful engine, it definitely requires some TLC in order to keep running strong. One of the most important aspects of keeping your 6.4L Powerstroke running smoothly is using high-quality oil with frequent oil changes.
While these engines are very powerful, they do have their design flaws, such as oil dilution due to the DPF system and premature rocker arm wear. Both of these issues can cause huge problems and cost a ton of money, but they can be avoided with frequent oil changes and frequent maintenance intervals.
In this article, we’ll be discussing the best oil for 6.4 Powerstrokes and giving you a few tips on how to properly care for your engine. Keep reading to learn more!
The 5 Best Oil for 6.4 Powerstroke
 Advertising | Best Overall 1. Shell Rotella T6 15W-40 |
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 Advertising | Best Value 2. Shell Rotella T6 15W-40 |
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 Advertising | Best 5W-40 3. Mobil 1 Turbo Diesel Truck 5W-40 |
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 Advertising | Best Value 5W-40 4. Schaeffer’s OTR Plus 5W-40 |
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 Advertising | Best 10W-30 5. Valvoline Premium Blue 10W-30 |
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1. Shell Rotella T6 Full Synthetic 15W-40 – Best Overall
Let’s begin with 15W-40, and what better way to start than with Shell Rotella T6? This is our top pick for the best oil for 6.4 Powerstroke engines for a few reasons.
Lubrication & Protection
Rotella T6 15W-40 exceeds the toughest requirements for the most recent and the strictest API-CK4 category. It demonstrated an 85% improvement in copper corrosion protection and a 98% improvement in lead corrosion protection, with nearly 50% more wear protection than required for the API-CK4 category. If this doesn’t convince you, nothing will.
But we’re not done yet. Rotella T6 knocked it out of the park during Volvo T-13 Oxidation Test and showed 70% more oxidation protection than required for API CK-4. Such excellent oxidation stability is exactly why this oil is capable of providing 1.5% better fuel economy without making any sacrifices when it comes to wearing protection.
Oxidation resistance is extremely important for the 6.4 Powerstroke, which is known to reach very high combustion chamber temperatures, especially in the 7th and 8th cylinders during DPF regeneration. By effectively controlling oxidation, Rotella T6 prevents oil molecules from “boiling off” and evaporating, thus the oil maintains viscosity for longer and minimizes power loss throughout the drain interval.
Bottom Line
We have nothing but good things to say about the Rotella T6 15W-40, and so do most other 6.4 Powerstroke owners. The Rotella T6 15W-40 is such an excellent full synthetic oil that it has become the go-to choice for many professional fleets and equipment operators.
If you’re looking for the best protection possible for your 6.4 Powerstroke, the Rotella T6 15W-40 is the way to go. No other oil comes close.
2. Shell Rotella T5 Synthetic Blend 15W-40 – Best Value
But what if oil changes are cutting into your budget a little too much and you’re looking for a more economical option? In that case, we recommend the Shell Rotella T5 Synthetic Blend 15W-40.
Lubrication & Protection
Yes, Rotella T5 is not a full synthetic oil, but don’t let that fool you. The synthetic blend formula of Rotella T5 still provides excellent protection and performance, all while being very affordable. Even with all the limitations of a synthetic blend, Rotella T5 meets the same strictest API CK-4 requirements AND even exceeds the maximum wear requirement for that category by 37%.
Now, while the T5 Rotella meets the same API category as the Rotella T6 and completely blows away conventional 15W-40 engine oils in terms of protection and performance, its synthetic blend composition does have a few downsides.
The first one is oxidation resistance to extremely high temperatures. Rotella T5 does meet all of the requirements, but it does not have the same level of thermal stability as the full synthetic Rotella T6 15W-40. As you probably know, extreme temperature oxidation stability is pretty important for the 6.4 Powerstroke, so it’s definitely something to keep in mind.
The second downside is that the Rotella T5 does not provide a 1.5% increase in fuel economy like the Rotella T6 above, although the difference is minuscule.
Bottom Line
The Rotella T5 15W-40 is definitely one of the best choices if you’re on a tight budget or want to minimize operating costs.
It’s a synthetic blend oil that still provides amazing protection and performance, all while being very affordable. The closest alternative is the Valvoline Premium Blue 15W-40.
3. Mobil 1 Turbo Diesel Truck 5W-40 Full Synthetic – Best 5W-40
Live in a colder region? Then you need oil that will flow easily in subzero temperatures, and the Mobil 1 Turbo Diesel Truck 5W-40 is just the ticket.
Lubrication & Protection
The Mobil 1 Turbo Diesel Truck 5W-40 is a full synthetic oil that’s designed for cold weather conditions. It flows easily in subzero temperatures and thus minimizes engine wear during cold starts, where most engine wear occurs.
The Mobil 1 Turbo Diesel Truck 5W-40 also provides excellent protection against extremely high temperatures, thanks to its full synthetic composition. This oil can easily handle the high combustion chamber temperatures of the 6.4 Powerstroke, even during active DPF regeneration. This means a cleaner engine and reduced likelihood of the pistons cracking or melting.
Because of its excellent performance and protection at both extremes of temperature, as well as compatibility with modern emission systems, the Mobil 1 Turbo Diesel Truck 5W-40 meets the requirements of API CK-4.
Bottom Line
The Mobil 1 Turbo Diesel Truck 5W-40 is our top choice for 6.4 Powerstroke owners living in regions with temperatures below 20°F. Even though 5W-40 is perfect for cold temperatures, it’s also recommended by Ford to be used for heavy-duty operating conditions and towing, so you can use it all year round.
4. Schaeffer’s OTR Plus 5W-40 Full Synthetic – Best Value 5W-40
If the Mobil 1 above is too expensive for your budget, then we recommend going with the Schaeffer’s OTR Plus 5W-40. Being an API CK-4 oil, it provides very similar protection and performance, but can be found for a much lower price depending on the time of year.
Lubrication & Protection
The OTR Plus 5W-40 is a full synthetic oil that’s designed for cold weather conditions. It flows easily in subzero temperatures and thus minimizes engine wear during cold starts.
When compared to conventional 5W-40 engine oils, the OTR Plus provides 71% better wear protection and 46% greater soot control, which is very important for the 6.4 Powerstroke. However, the main selling point of the OTR Plus, apart from price, is its additive package – Micron Moly and Penetro.
These two unique friction modifiers work together to provide an extra layer of protection for your engine, especially during extended oil change intervals. The OTR Plus is also a low ash oil and is compatible with all emission control devices, including SCR and DPF systems.
Bottom Line
The Schaeffer’s OTR Plus 5W-40 is a great alternative to the Mobil 1 Turbo Diesel Truck 5W-40 if you’re on a tight budget. It provides excellent protection and performance at temperatures ranging from -20°F all and well over 100°F, all while being very affordable.
5. Valvoline Premium Blue SAE 10W-30 Synthetic Blend – Best 10W-30
If the best viscosity grade for your 6.4 Powerstroke is 10W-30, then we recommend going with the Valvoline Premium Blue. It meets the requirements of API CK-4 and has the lowest price tag of all the oils on our list.
Lubrication & Protection
The Valvoline 10W-30 is a synthetic blend oil that provides excellent protection against wear and tear, even during extended oil change intervals, thanks to its healthy Zinc and Phosphorous content (around 900 ppm of both).
It also does a great job of controlling soot and keeping your DPF and SCR systems clean, which is important for the longevity of your engine and aftertreatment systems that are known to cause problems in the 6.4 Powerstroke.
Because of its low price and excellent protection, the Valvoline 10W-30 is one of the most popular oils used in the 6.4 Powerstroke, especially among fleet operators.
Bottom Line
When it comes to 10W-30 viscosity engine oils, the Valvoline Premium Blue is the best you can get for your 6.4 Powerstroke in multiple ways. It’s very affordable, meets the latest and strictest API standards, and provides excellent protection against wear and tear, as well as soot build-up.
How to Choose the Best Oil for Your 6.4 Powerstroke
Now that you’ve seen our top picks for the 6.4 Powerstroke, let’s quickly go over everything you need to know in order to get the best oil for YOUR 6.4 Powerstroke.
Get the Right Viscosity Grade for Your Driving Conditions
One of the most important things to keep in mind when choosing engine oil for the 6.4 Powerstroke is to get the right viscosity grade for your driving conditions and temperature. Failure to choose the right viscosity will likely reduce the life of your engine and might even destroy it.
The best way to do this is to consult your owner’s manual, but if you don’t have one, here’s a table taken straight from the owner’s manual that shows the recommended oil viscosity grades for the 6.4 Powerstroke depending on ambient temperature.
| Ambient Temperature Range | Recommended Oil Viscosity |
| 20°F to over 100°F | 15W-40 |
| 0°F to 50°F | 10W-30 |
| -20°F to over 100°F | 5W-40 |
| Over -20°F to 50°F | 0W-40/0W-30 |
Also, remember that 15W-40 and 5W-40 must be used for towing or heavy duty driving. Lastly, no matter which viscosity engine oil you choose, you must use a block heater at temperatures below -10°F.
Full Synthetic VS Synthetic Blend VS Conventional For 6.4 Powerstroke
The next thing you need to decide on is whether you want to go with full synthetic oil, a synthetic blend, or conventional engine oil.
As a general rule of thumb, we recommend going with a full synthetic oil for the 6.4 Powerstroke if it’s not too expensive for you. Full synthetic oil is better in every single way, and it can easily handle extremely hot temperatures that the 6.4 Powerstroke produces inside the turbo and during DPF regeneration.
That being said, a synthetic blend can also be used in the 6.4 Powerstroke to cut down costs as long as it meets the requirements of API CK-4. Just keep in mind that it might be a good idea to change your oil more often with a synthetic blend if you haven’t deleted the DPF.
As for conventional oil, it can be used, but we certainly do not recommend it. The fact that it’s not as good as synthetic oil in high temperatures is a big issue for the 6.4 Powerstroke, and it doesn’t do as good of a job protecting your engine against soot either. The risk of clogging up your DPF sooner and poor high temperature thermal stability outweighs the low price.
API Standards For 6.4 Powerstroke Engine Oils
According to the owner’s manual, the 6.4 Powerstroke needs engine oil that meets the requirements of API CJ-4 or newer. Ideally, you should go with the more recent API CK-4, because that category is stricter and provides better protection against wear, and even helps the DPF stay clean for longer.
Does the 6.4 Powerstroke Need Oil Additives?
Oil additives can be used in the 6.4 Powerstroke, but the engine does not need them if you’re using full synthetic or synthetic blend API CJ-4 oil.
It is more important to change the engine oil often (every 5000 miles) to prevent wear due to possible oil dilution by fuel if the DPF is still present.
Also Read: The Best Oil for 6.7 Powerstroke
6.4 Powerstroke Engine Care Tips
A lot of people say that the 6.4 Powerstroke is unreliable, but that’s not true, especially if you follow regular and proper maintenance intervals.
Sure, the engine does have its design flaws, but you can considerably reduce the chances of something going wrong by following these tips.
Severe Operation Maintenance Intervals Highly Recommended in All Cases
The single best way to make sure your 6.4 Powerstroke lasts a long time is to follow the severe operation maintenance intervals that are described in the owner’s manual, regardless of how you use your truck.
| Service Procedure | Recommended Interval |
| Replace Engine Oil & Filter | 5,000 miles |
| Replace Fuel Filter | 10,000 miles |
| Replace Air Filter | 10,000 miles |
| Replace Coolant | 50,000 miles/3 Years |
| Replace Automatic Transmission Fluid & Filter | 30,000 miles |
| Replace Manual Transmission Fluid | 100,000 miles |
| Replace Transfer case Fluid | 60,000 miles |
| Replace Front Differential Fluid | 50,000 miles |
| Replace Rear Differential Fluid | 50,000 miles |
As you can see, the maintenance intervals are pretty short, but they do make sense financially since once something goes wrong with the engine, you have to take the cab off to gain access to it.
We believe 100% that the 6.4 Powerstroke is worth the extra maintenance in the end. You can avoid a lot of problems just by following the severe operation maintenance schedule.
Should You Delete the DPF?
The DPF system on the 6.4 Powerstroke is definitely problematic. It’s poorly designed and uses the injectors in cylinders 7 and 8 to put fuel into the exhaust for regeneration. Ideally, you’d want to use a dedicated 9th injector, but that’s not the case with the 6.4 Powerstroke.
This tends to cause a few problems, mainly oil dilution and melted 7th and 8th pistons in extreme cases. During regeneration, some fuel slips through the piston rings and gets mixed with engine oil. It isn’t too much of a problem if the DPF regeneration happens infrequently, but if the truck is driven mainly in stop-and-go traffic with very long idle times, then it becomes a problem.
A lot of people delete the DPF, and while it’s illegal to do so, it does seem to help a lot. However, you can reduce the chances of those problems occurring by reducing idling times, minimizing stop-and-go driving, and changing the engine oil every 5000 miles.
The DPF needs some highway driving once in a while to properly get rid of the soot. If you mainly drive in the city, then the DPF will eventually get full and a regeneration cycle will be triggered. If this happens too often, it will lead to oil dilution and, eventually, piston failure.
Final Thoughts
While the 6.4 Powerstroke does have its fair share of problems, we still think it’s a good engine. It’s powerful, efficient, and, with proper maintenance, can last a long time.
Just remember to follow the severe operation maintenance schedule, change the oil often, and try to avoid stop-and-go driving as much as possible. Using full synthetic oil that meets API CK-4 is also extremely important if you want to avoid wear and tear on the engine.
If you do all of that and choose from our top 5 picks for the best oil for 6.4 Powerstroke, then you should have no problem keeping your engine running well for a long time.
Do you have any questions or tips for keeping the 6.4 Powerstroke running strong? Let us know in the comments below or contact us by email!
Eddie is the co-founder of CarCareCamp.com, and the site’s primary contributor.
Under his belt, Eddie has a bachelor’s degree in Automotive Electronics Engineering and almost a decade of experience working as a semi-truck technician (specializing in electrics).
