Trying to find "The One" 15w40 oil to use across my whole fleet (pre-emission diesel and gas engines)

I have 40 gallons of oil gifted to me, once they run out I'm going to use delvac 1300. It's so cheap at Walmart and the cold flow numbers are so great, I just don't see another oil that could take it's place.

I don't own diesels, only high mileage older gas motors and an air cooled skid steer.
 
Hey all. Long-time lurker but first-time poster. I apologize if I am beating a dead horse here, but I've been doing a lot of research (and have done virgin oil analyses on most of the major brands of HDEO available in my area), and still cannot come to a good conclusion. I would like to hear some opinions from the forum - maybe you can help me stop overthinking (and hopefully the info from the VOA's will help others here).

To start off, nothing in my fleet is newer than 2000 model year. I tinker with old tractors in my spare time, which have engines ranging from air-cooled Kohler single-cyl and Onan two-cyl gas, Yanmar & Kubota 3-cyl liquid-cooled diesels, two-cylinder gas John Deere's (which originally called for a low-ash SAE30), and some 50-60 HP three-cylinder diesels. Also have plans of collecting more antique tractors (both gas and diesel) in the future, along with old semi trucks (Cat/Cummins/Mack diesel powered). My tow rig is a Ford F-250 with 7.3L Powerstroke (pre-emissions). I've spent way too long buying different kinds of oils for all of my equipment and would like to find "THE ONE" 15w40 oil that I can use across my whole fleet - an oil that would fulfill the "low ash" requirement for my air cooled Kohler engines (splash lubed with no filter), but still provide good lubrication for the Onan air-cooled twins (with an oil pump), the small diesels, all my antique tractors, and my truck. Something I can easily buy in a 55-gallon drum that I won't have to worry about becoming obsolete (like JD Torq-Gard 15w40 or Mobil Delvac MX - both originally rated CI-4+ and getting harder to find here in the US). My machines all get used throughout the year (for work and play), and they all get a decent amount of hours put on them per year, but not enough that I can justify the cost of synthetic oil (or the need to deal with an independent sales rep - especially if I'm in a pinch).

I've had VOA's performed on the following conventional diesel oils which are readily available at most auto parts stores and dealerships around me (plus I work for a Case IH dealer that frequently stocks the Akcela No. 1 and Mobil Delvac 1300 oils). The exception being AMSOIL 15w40 which I used as the control. The results from the lab tests are as follows (and yes, I'm aware they are all decent choices, but if I'm buying a 55-gallon drum I want to make sure all my bases are covered):

View attachment 147854

From the results, it would seem that the Delvac MX, JD Torq-Gard, TSC Traveller, and Case IH/Akcela No. 1 (all highlighted) have the best combination of additives, detergents, and TBN. While my air-cooled Kohler engines typically require a low-ash, non-detergent oil, I don't know that I'll be able to achieve that without sacrificing some of the additives that the bigger engines need. I was leaning toward JD Torq-Gard and Mobil Delvac MX due to their high additive packages, but both of them are practically obsolete (and expensive if you can find them in a 55-gal anywhere). Working for a Case IH dealer I'm also leaning toward the Akcela No.1 since it's readily available, but it doesn't really qualify as a "low ash" oil. I've always used the Motorcraft 15w40 in my 7.3 Powerstroke, as I know Ford's WSS-M2C171-F1 spec is basically in a class of its own.

Am I better off just buying a low-ash SAE30 for my Kohler's and sticking with a 15w40 for everything else? Is there really a good all-around oil that fits all these categories? Am I just overthinking it??
GET CHEVRON OIL, OR NAVISTAR OIL.
 
I run Mobil delvac1 5w40 in every machine and vehicle I own but my maxima and tahoe. They get 5w30. Log splitters, two side by sides, three different generators, two tractors. Zero issues and do 15k oci on my maxima, tundra, and tahoe.
I feel obliged to share a story “from the trenches” based on one of the few field experiences I’ve had with a high-hour teardown of an engine run on Delvac 1.

A large mining customer of Cummins had an excavator with a QSK60 in it that they decided was at the end of its life at somewhere around 1.6 million gallons of fuel burn. This is a 60L V16 with typical ratings of 2750hp. This particular unit burned a LOT more fuel than most engines of this kind, which are typically ready for an overhault around 20,000 hours and 1M gallons of fuel burn.

The fuel system parts were returned to us because we were interested in their condition as this was a very rare data point for us at the factory.

Not only was the engine run on Delvac 1 oil, it was using GTL diesel fuel because the location of the site made it very practical to do so. So, synthetic fuel and oil. This particular fuel was notably higher lubricity than most (HFRR< 400)

At about 50% beyond the intended component life, the injectors were barely worn. They’d lost a bit of fueling (typical) but were just barely out of spec for *brand new* injectors.

But the most amazing part was the inside of the High pressure fuel pump. On these engines, the pump’s roller cam followers are typically the highest loaded oil film in the entire engine. And in this particular era (early 2010s), there were lubrication-related failures occurring on the pumps in some applications.

Yet this pump which had gone FAR past its intended lifespan looked immaculate. The cam followers had almost no perceptible wear. The cam itself, front and rear bearings, etc could have passed for new parts. All of us back at the factory were stunned not just by what we saw in the teardown but what we knew it had been doing: Excavators have an average duty cycle of nearly 90%.

What I took away from this experience:
1) Delvac 1 is one heck of an oil— or was in its CI-4+ formulation
2) high lubricity, high purity fuels are wonderful for injectors
3) Do not fear prolonged operation at higher load. It’s low load and cold start that kill engines, it seems
 
I feel obliged to share a story “from the trenches” based on one of the few field experiences I’ve had with a high-hour teardown of an engine run on Delvac 1.

A large mining customer of Cummins had an excavator with a QSK60 in it that they decided was at the end of its life at somewhere around 1.6 million gallons of fuel burn. This is a 60L V16 with typical ratings of 2750hp. This particular unit burned a LOT more fuel than most engines of this kind, which are typically ready for an overhault around 20,000 hours and 1M gallons of fuel burn.

The fuel system parts were returned to us because we were interested in their condition as this was a very rare data point for us at the factory.

Not only was the engine run on Delvac 1 oil, it was using GTL diesel fuel because the location of the site made it very practical to do so. So, synthetic fuel and oil. This particular fuel was notably higher lubricity than most (HFRR< 400)

At about 50% beyond the intended component life, the injectors were barely worn. They’d lost a bit of fueling (typical) but were just barely out of spec for *brand new* injectors.

But the most amazing part was the inside of the High pressure fuel pump. On these engines, the pump’s roller cam followers are typically the highest loaded oil film in the entire engine. And in this particular era (early 2010s), there were lubrication-related failures occurring on the pumps in some applications.

Yet this pump which had gone FAR past its intended lifespan looked immaculate. The cam followers had almost no perceptible wear. The cam itself, front and rear bearings, etc could have passed for new parts. All of us back at the factory were stunned not just by what we saw in the teardown but what we knew it had been doing: Excavators have an average duty cycle of nearly 90%.

What I took away from this experience:
1) Delvac 1 is one heck of an oil— or was in its CI-4+ formulation
2) high lubricity, high purity fuels are wonderful for injectors
3) Do not fear prolonged operation at higher load. It’s low load and cold start that kill engines, it seems
This mirrors @Doug Hillary's experience with Delvac 1. @Pablo shared some bearing and liner pics for him here at one point. He ran OTR truck trains through the Australian outback testing Delvac 1 for Mobil and at 1.6 million km, they did a random tear-down of one of the engines and it was pristine. No liner wear, bearings measured "as new". It was impressive.
 
This mirrors @Doug Hillary's experience with Delvac 1. @Pablo shared some bearing and liner pics for him here at one point. He ran OTR truck trains through the Australian outback testing Delvac 1 for Mobil and at 1.6 million km, they did a random tear-down of one of the engines and it was pristine. No liner wear, bearings measured "as new". It was impressive.
I really wonder if the current Delvac 1 formulas can pull off such feats or if CJ and later versions with <1.0 SAPS have been neutered.

I’d be tempted to think the only real impact of lower SAPS would be shorter max OCIs, you’d think the basic wear protection and cleanliness should hold.
 
Here's another 15/40 story :

20250213_124953.webp
 
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