Explain like I'm 5 - sump capacity and extended intervals

[Vitamin Yoda]

The emergency diesel generator (250kW) in our condo has a sump capacity of 9 gallons!!! The engine was made by Deere.

Most semi trucks have 10 to 14 gallons sumps. Given how much the oil pans extend downwards beyond the lowest position of the crankshaft, they could have built most of them with 4 gallon sumps. However, there's a good reason they didn't.

 

[b_b]

That's a pretty short interval for a modern engine.

My ram is 7.5qt which comes out to 4300mi/7000km.

A 5qt sump would only be 3000mi/4700km.

While it may be appropriate for some situations, it sounds like old school thinking to me.

depends on use case. i follow this for the most part, i stick to 5k miles on a 9qt sump. that puts the average driver at two oci's a year. which i consider to be a nice middle ground between every 3 months and once a year.

 

[dfarr67]

depends on use case. i follow this for the most part, i stick to 5k miles on a 9qt sump. that puts the average driver at two oci's a year. which i consider to be a nice middle ground between every 3 months and once a year.

Work truck '19 k1500 chev 5.3L, run some dusty gravel, salt dust in the winter, service every three months at this interval mileage, semi synthetic used. 170k km, never a problem with DOD, trans had some programing updates, just putting in a transfer case now. I just don't believe in stretching it out new or old thinking- fleet policy tho not mine.

 

[BMWTurboDzl]

I didn't want to hijack another thread, but I gotta ask the collective wisdom here. Not the internet expertses, but the people that REALLY know what they are talking about.

Is it really just this simple? Aren't oil filters the trashcan? @Vitamin Yoda - sometimes I'm a smarty pants, but this one really has me thinking. I need more than oil just has heaps of trash in it, which it shouldn't, if a filter is doing its job. About all that comes out of my sump is used up oil darkened with soot and diluted with gasoline.

EDIT: and wear metals etc..... but measuring in ppm is still measuring in ppm.

View attachment 203462

Answer: Kinda.

Oil filters will only capture particles of "X" size. Smaller particles (ex, soot) which pass thorough it contribute to the dark color of used motor oil.

With larger sumps think of "The solution to pollution is dilution". Larger sump = greater capacity to dilute the same amount of wear/combustion byproducts over the same interval.

 

[KrisZ]

More oil doesn’t mean better. For short commutes, or not a lot of highway driving, a smaller sump will allow the oil to heat up faster.

So if you have a large sump and do lots of short trips, I highly doubt you could extend the OCIs based on capacity. If anything it could mean shorter OCIs when compared to an engine that holds less oil because the larger sump would also hold more fuel and moisture in the oil.

 

[dfarr67]

More oil doesn’t mean better. For short commutes, or not a lot of highway driving, a smaller sump will allow the oil to heat up faster.

So if you have a large sump and do lots of short trips, I highly doubt you could extend the OCIs based on capacity. If anything it could mean shorter OCIs when compared to an engine that holds less oil because the larger sump would also hold more fuel and moisture in the oil.

In NWT Canada, engines were destroyed due to owners not getting out on the highway for a duration to cook out the moisture. At winter temps of -25-45C the water at the bottom of the oil pan could and would freeze the pick up and starve the engine of oil. I had to drill moisture drains in the oe mufflers to relieve water build up as the exhaust would gurgle, worst case cars would not start due to iced up exhaust. So I would say short trips are severe duty.

 

[mr_boring]

@Vitamin Yoda and @KrisZ - I drive my F150 as much as 1300 miles per week, and many of those runs are between 75 and 80 miles at relatively high speeds. You both provide good feedback about fuel dilution.

I have fuel dilution. It doesn't matter if I pull my truck into my garage directly after an 80 mile trip or if I change it after I've hit up 3 short trips to a grocery store on a Saturday. It still reeks of gas. I think less burns off than we think, unless it burns off and still leaves the odor of raw gas. 2.7 with dual injection.

@BMWTurboDzl - good answer, I'm inclined to go with "kinda" but that the difference is going to be minimal after a few k - leading to "not really" if we were talking about 15k.

Oil degrades at the same pace whether it's 5 quarts or 7 - that's somewhat dependent upon the vehicle and somewhat dependent on the oil used - shout out to Dave of course, though a few others definitely get honorable mention. Soot etc gets a bit more spread out but still circulates and by 10k it's all going to be as black as midnight (mines pretty dark by 3-4k and I have had a 9 quart sump and a 6 quart sump recently that confirm that. I doubt it matters if soot is 1100ppm vs 850ppm (just numbers I made up) as it's all circulating.

Appreciate the answers so far. Good stuff.

 

[mr_boring]

Most semi trucks have 10 to 14 gallons sumps. Given how much the oil pans extend downwards beyond the lowest position of the crankshaft, they could have built most of them with 4 gallon sumps. However, there's a good reason they didn't.

From what I understand, and I don't understand much, but a diesel mechanic for a local mine and I were talking about this very thing Saturday. He was familiar with HPL (they don't use it) from working in another mine out west (that used it) and he casually mentioned the enormous amounts of waste oil they generate and how some of that equipment almost literally takes a drum to fill. I asked why, he said that the trucks move so much weight that it does help keep the oil cool.

 

[KrisZ]

I doubt it matters if soot is 1100ppm vs 850ppm (just numbers I made up) as it's all circulating.

Appreciate the answers so far. Good stuff.

Good discussion so far for sure

The soot concentration matters because at certain point the oil will not be able to hold it in suspension and it will start depositing in the engine.

But as far as wear, yeah it probably doesn’t matter.

 

[Vitamin Yoda]

The soot concentration matters because at certain point the oil will not be able to hold it in suspension and it will start depositing in the engine.

It will polish bearings and stretch the timing chain(s).

I have fuel dilution. It doesn't matter if I pull my truck into my garage directly after an 80 mile trip or if I change it after I've hit up 3 short trips to a grocery store on a Saturday. It still reeks of gas. I think less burns off than we think, unless it burns off and still leaves the odor of raw gas. 2.7 with dual injection.

From what I've seen, installing an oil catch can correctly on the EcoBoost helps greatly with keeping the oil clean and the engine in good health. I'd advise you to look into that.

 

[BMWTurboDzl]

Oil degrades at the same pace whether it's 5 quarts or 7 - that's somewhat dependent upon the vehicle and somewhat dependent on the oil used.

All else being equal I would say "not really" because when making these comparisons you must control for the oil and the engine. Remember larger sumps have more capacity so the oil will reach condemnation further down the line compared to the same engine with a smaller sump. Extrapolate this out to extremes. Say your engine could have a sump of 1 liter or 10 liters. 1 liter may last 2k miles. 10 liters of the same oil could last 30k miles. Now I don't know how an actual condemnation curve would look like going from say 1 to 10 liters but I think you get the jist of what I'm saying. In any case there are packaging restraints that automakers must also deal with. Sumps can only be so large.

 

[D1sc]

Hope this helps strainer on oil pickup keeps large crap out of the filtering system or stuff like this I fished out through my drain plug would cause problems

 

[dfarr67]

It will polish bearings and stretch the timing chain(s).


From what I've seen, installing an oil catch can correctly on the EcoBoost helps greatly with keeping the oil clean and the engine in good health. I'd advise you to look into that.

I run catch cans on everything- there are many detractors....but the crap I dump at each oil change is proof enough for me, especially on the Honda DI engine.

 

[Vitamin Yoda]

I run catch cans on everything- there are many detractors....but the crap I dump at each oil change is proof enough for me, especially on the Honda DI engine.

IMHO the inconvenience is worth it. Not to mention that the ECU doesn't have to pull back timing, and you keep your valves and pistons clean.