2024 6.7L SO Cummins 38.2k mi; VPBE 7.9k mi

[EveryoneIsAnotherYou]

UOA for 2024 RAM 3500 6.7L SO Cummins @ 38,207 Miles & 30% Towing Running R99 Renewable Diesel

• Just posting my latest UOA for others interested in comparing the same engine as mine (Cummins 6.7L Standard Output).
• ~30% of my miles are towing a 8,000lb travel trailer.
• I switched over to Valvoline Premium Blue Extreme Full Synthetic Motor Oil 5W-40 for the past 3 oil changes.
• My only comment/concern is that fuel dilution begins to creep into the 4% range after about 8,000 miles (possibly caused by ~26% idle time).
• I run mostly R99 Renewable Diesel.
• Will be changing my oil and filter next week.

 

[Bighorn2500]

Idle time will impact your fuel dilution for sure.

Cummins guideline states 5% fuel dilution in their service bulletin from years ago so you are due for a change IMO from the data provided.

 

[Danno]

Why renewable diesel?
I would run it on good old fashioned dino diesel and see if dilution and or other numbers change.
Sometimes the advertisements don't live up to the hype. Just saying.

 

[Hohn]

Why renewable diesel?
I would run it on good old fashioned dino diesel and see if dilution and or other numbers change.
Sometimes the advertisements don't live up to the hype. Just saying.

Renewable diesel is primarily from Hydrotreated Vegetable Oil (HVO). It's essentially almost a pure paraffin.

That means it has good lubricity and a host of other desirable features (high cetane, good cold properties, etc). But it also means it entirely lacks the lighter aromatic (benzene) constituent component of a petroleum diesel fuel.

@EveryoneIsAnotherYou:

R99 is a bit harder to "cook off" with loaded running. And simply put, your fraction of loaded running is both too low in proportion and too low in load. To cook off 5% fuel dilution, you'd need something closer to multiple Baker Grade runs at full throttle and max GCVWR.

Do your best to stop idling the truck. Skip the drive through and go inside-- it saves time, saves the truck, and burns a couple more calories. That kind of thing. Shut the engine off and crack the window if you need to.

Idling a diesel has never been harmless, but it's more consequential now than ever before. Make every reasonable effort not to do so. Your engine and ESPECIALLY the aftertreatment will thank you.

Keep using the R99, it's good stuff. Just be sure to avoid any blend of REnewable and Bio (R79B20 or similar). Renewable has poor solvency and cannot prevent the biodeposits. We've had a lot of field test probems on engines running renewable blended with Bio. Skip the bio, keep the renewable.

If you want to run bio, make sure it's blended only with petrodiesel.

More detail here:
https://mart.cummins.com/imagelibrary/data/assetfiles/0076899.pdf

 

[EveryoneIsAnotherYou]

Why renewable diesel?
I would run it on good old fashioned dino diesel and see if dilution and or other numbers change.
Sometimes the advertisements don't live up to the hype. Just saying.

@Danno Great question! There are several reasons why I go out of my way to hunt down R99 whenever I can.

Pros:

1. My money stays in the USA. At Washington's 2025 fuel prices (~$4.70-5.70/gallon lately), I'm spending well over $11,000/year on diesel, and fuel is probably my 5th biggest expense besides taxes, mortgage, car payment, etc. R99 Renewable Diesel is made in the USA with American resources, labor, and ingenuity. My dollars are a vote for the regimes and politics I want to see more of in the world. I don't want my $11k going to support monarchies that dismember US-based journalists; make their daughters see the world through a slit in a veil and be prevented from driving a car; chop the heads off gay people in marketplaces on Friday mornings; or any of the other awful things that tend to happen when unethical minds control oil-rich countries the world over. Pick almost any petroleum-rich country, and you'll find a Mafia-like ruling class that controls the petrol at the expense of their working class. Yes, the US extracts petrol, but we also import it. For me, R99 is a way of (financially) rejecting those systems. A drop in the ocean, but what is the ocean but a multitude of drops?
2. My engine runs quieter and smoother. My Cummins 6.7L purrs just like a smooth gasoline engine under heavy acceleration. When it's switched over to petroleum diesel #2, I hear faint chatter under acceleration, even with Hot Shots EDT additive. Chatter means parts are vibrating, banging, or rubbing more.
3. Fewer regens and less soot. R99 burns cleaner with less soot, resulting in fewer regen cycles and DPF issues. At least, this is what is claimed.
4. It's close to carbon and methane-neutral. R99 makes use of above-ground resources in a closed loop. I'm adding almost no net new carbon or methane to the atmosphere. Crops and waste fats from animal rendering make R99. It is a sustainable fuel.
5. Future-proof for future generations. When petroleum runs out, future generations can bioengineer algae or hybrid plants to create diesel oil - it's easier to bioengineer a diesel supply chain because diesel takes less chemistry/refinery work than gasoline and diesel oil is less volatile to handle and transport. I want my $11k/year spend to support the engineering and systems that will create sustainable fuels tomorrow. “A society grows great when old men plant trees whose shade they know they shall never sit in."--Greek Proverb

Cons:

1. The price is the same (usually with 10% - but in Washington, I pay 10-15% more). In Washington, R99 is only available from a handful of commercial cardlock stations, and it costs 10-15% more than petroleum diesel gas station prices. I suck it up and eat the cost. In Oregon, the price is the same or less than petroleum diesel. In California, it's the same or less. When I use 76's Fuel Forward app to prepay, they give me a $0.30/gallon discount. For a Washington resident, though, it's not easy to hunt down and costs at least $0.70/gallon more than ULSD#2.
2. The BTUs per gallon are slightly less. If I recall, R99 has about 5% fewer BTUs per gallon than ULSD#2. I haven't done any extremely scientific tests, but I'm pretty sure I get about 0.5-1mpg less fuel economy when towing on R99 compared to petroleum diesel.
3. It's hard to find (outside of California). I have to use a combination of apps (Fuel Forward), Alt Fuel, and Google to find R99, but with my 55 gallon tank, I've been able to find it in Boise, Idaho, and rural Nevada and keep my road trips greener and cleaner.

The Pros outweigh the Cons for me. I hope some of the info above makes someone think about their fuel choices because the most powerful vote any of us has is where, how, and why we spend our dollars.

 

[Brons2]

@Danno Great question! There are several reasons why I go out of my way to hunt down R99 whenever I can.

Pros:

1. My money stays in the USA. At Washington's 2025 fuel prices (~$4.70-5.70/gallon lately), I'm spending well over $11,000/year on diesel, and fuel is probably my 5th biggest expense besides taxes, mortgage, car payment, etc. R99 Renewable Diesel is made in the USA with American resources, labor, and ingenuity. My dollars are a vote for the regimes and politics I want to see more of in the world. I don't want my $11k going to support monarchies that dismember US-based journalists; make their daughters see the world through a slit in a veil and be prevented from driving a car; chop the heads off gay people in marketplaces on Friday mornings; or any of the other awful things that tend to happen when unethical minds control oil-rich countries the world over. Pick almost any petroleum-rich country, and you'll find a Mafia-like ruling class that controls the petrol at the expense of their working class. Yes, the US extracts petrol, but we also import it. For me, R99 is a way of (financially) rejecting those systems. A drop in the ocean, but what is the ocean but a multitude of drops?

I agree with all that, and would add that the fiduciary responsbility of oil companies in the USA and friendly countries is to maximize shareholder value and IMO it can lead to questionable company ethics.

I like what you're doing here, carry on. I'm going to have to look more into R99.

 

[Brons2]

Wow. You can basically only get this R99 fuel on the west coast, even though there are companies that actually refine it in the South.

I have been looking at diesel pusher motorhomes and if we acquire one, I'd like to use this fuel. But it seems to be unobtainium in Texas.

 

[Hohn]

@Danno Great question! There are several reasons why I go out of my way to hunt down R99 whenever I can.

Pros:

1. My money stays in the USA. At Washington's 2025 fuel prices (~$4.70-5.70/gallon lately), I'm spending well over $11,000/year on diesel, and fuel is probably my 5th biggest expense besides taxes, mortgage, car payment, etc. R99 Renewable Diesel is made in the USA with American resources, labor, and ingenuity. My dollars are a vote for the regimes and politics I want to see more of in the world. I don't want my $11k going to support monarchies that dismember US-based journalists; make their daughters see the world through a slit in a veil and be prevented from driving a car; chop the heads off gay people in marketplaces on Friday mornings; or any of the other awful things that tend to happen when unethical minds control oil-rich countries the world over. Pick almost any petroleum-rich country, and you'll find a Mafia-like ruling class that controls the petrol at the expense of their working class. Yes, the US extracts petrol, but we also import it. For me, R99 is a way of (financially) rejecting those systems. A drop in the ocean, but what is the ocean but a multitude of drops?
2. My engine runs quieter and smoother. My Cummins 6.7L purrs just like a smooth gasoline engine under heavy acceleration. When it's switched over to petroleum diesel #2, I hear faint chatter under acceleration, even with Hot Shots EDT additive. Chatter means parts are vibrating, banging, or rubbing more.
3. Fewer regens and less soot. R99 burns cleaner with less soot, resulting in fewer regen cycles and DPF issues. At least, this is what is claimed.
4. It's close to carbon and methane-neutral. R99 makes use of above-ground resources in a closed loop. I'm adding almost no net new carbon or methane to the atmosphere. Crops and waste fats from animal rendering make R99. It is a sustainable fuel.
5. Future-proof for future generations. When petroleum runs out, future generations can bioengineer algae or hybrid plants to create diesel oil - it's easier to bioengineer a diesel supply chain because diesel takes less chemistry/refinery work than gasoline and diesel oil is less volatile to handle and transport. I want my $11k/year spend to support the engineering and systems that will create sustainable fuels tomorrow. “A society grows great when old men plant trees whose shade they know they shall never sit in."--Greek Proverb

Cons:

1. The price is the same (usually with 10% - but in Washington, I pay 10-15% more). In Washington, R99 is only available from a handful of commercial cardlock stations, and it costs 10-15% more than petroleum diesel gas station prices. I suck it up and eat the cost. In Oregon, the price is the same or less than petroleum diesel. In California, it's the same or less. When I use 76's Fuel Forward app to prepay, they give me a $0.30/gallon discount. For a Washington resident, though, it's not easy to hunt down and costs at least $0.70/gallon more than ULSD#2.
2. The BTUs per gallon are slightly less. If I recall, R99 has about 5% fewer BTUs per gallon than ULSD#2. I haven't done any extremely scientific tests, but I'm pretty sure I get about 0.5-1mpg less fuel economy when towing on R99 compared to petroleum diesel.
3. It's hard to find (outside of California). I have to use a combination of apps (Fuel Forward), Alt Fuel, and Google to find R99, but with my 55 gallon tank, I've been able to find it in Boise, Idaho, and rural Nevada and keep my road trips greener and cleaner.

The Pros outweigh the Cons for me. I hope some of the info above makes someone think about their fuel choices because the most powerful vote any of us has is where, how, and why we spend our dollars.

It’s worth mentioning the HVO/RD fuel has lower energy per gallon almost entirely because it is less dense. So each gallon of fuel is actually less MASS of fuel, on the order of 8%-12%.

So with no other changes, one could rightly expect a fuel economy loss of about 10%. The fact that you are experiencing only a small mpg loss is testament to the fuel’s high cetane index and clean-burning.