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

[mr_boring]

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.

 

[Vitamin Yoda]

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.

Here is what @High Performance Lubricants had to say about the sump size:

Yes the sump size matters. The sump is your trash can. The bigger the can the longer the drain. That can gets its trash from the fuel. You want to change the oil just before that can is full as long as everything else is working as it should. UOA trend data becomes a useful tool for verifying everything is working according to plan.

Link: https://bobistheoilguy.com/forums/t...-mileage-for-oil-changes.364235/#post-6355407

 

[bullwinkle]

More oil means it SHOULD take longer to break down (shear, oxidize, etc.) and will be able to hold more contaminants in suspension than less oil can. Unfortunately UOAs & particle counts are needed to see exactly how long that is…

 

[dfarr67]

My shop says 1000km per liter.

 

[Zee09]

More oil means it SHOULD take longer to break down (shear, oxidize, etc.) and will be able to hold more contaminants in suspension than less oil can. Unfortunately UOAs & particle counts are needed to see exactly how long that is…

Good to know as I only filled the sump half way on my vehicles because with less oil I thought it would filter faster...

 

[SC Maintenance]

I work in the manufacturing / industrial world, and there are tons of studies that say wear particles down to a micron cause a reasonable amount of machine wear. Lots of machinery is going to micron level bypass filters for lubricants.

I don't think its a stretch to infer this matters to engines as well, and the best filters based on testing take out around 50% of 10um particles.

So your oil filter is the trash can for the large stuff, and the sump is the trash can for the rest. Not to mention dilution and other crap.

 

[eljefino]

If your typical drive is ten miles and you don't get all that oil up to temperature, it's not going to boil contaminants out at any reasonable speed.

I keep my yard plow truck a quart low on purpose. It only runs 10-15 minutes at a time.

 

[DemoFly]

There's a lot of different tangential conversations about this. But the simplest reason is modern oil is a detergent which holds contaminants in suspension. There's simply more volume to hold contaminants, and more total detergent.

I imagine sump size of an engine has more to do with engineers balancing thermal efficiency of the engine and expected heatsoak.

 

[Vitamin Yoda]

If your typical drive is ten miles and you don't get all that oil up to temperature, it's not going to boil contaminants out at any reasonable speed.

I keep my yard plow truck a quart low on purpose. It only runs 10-15 minutes at a time.

You're forgetting about blow-by gasses, they're hot. That's where the contaminants come from, and are fed right back into the intake via the PCV. The bigger concern is condentation. If the engine doesn't run for long enough, you keep adding water to your oil. One of the first places that shows signs of this happening is the oil filler cap on some vehicles. Unfortunately, you gain nothing by running your yard plow low on oil. If you're worried about condentation the run any API SP "Resource Concerving" oil in it as they have lower amount of detergents and therefore tend to accumulate less water.

 

[Vitamin Yoda]

I work in the manufacturing / industrial world, and there are tons of studies that say wear particles down to a micron cause a reasonable amount of machine wear. Lots of machinery is going to micron level bypass filters for lubricants.

I don't think its a stretch to infer this matters to engines as well, and the best filters based on testing take out around 50% of 10um particles.

So your oil filter is the trash can for the large stuff, and the sump is the trash can for the rest. Not to mention dilution and other crap.

A few years ago I've read a Machinery Lubrication article about the relationship between oil viscosoty, HTHS, and contaminants. The jist of was that a motor oil with higher HTHS can keep small particles better in suspention and minimize wear than thin oil. Since then, especially in GDI and T-GDI engines, I try to run oils that have a HTHS of at least 3.5. Soot alone killed so many GDI and T-GDI engines due to the owners running 0W-20 and 5W-20 oils in them for an extended period of time. A lot of the time, even becore the soot manages to stretch the timing chain, it uaually gets the rod bearings first. Just ask Hyundai what happend with their Theta II engines. Nope, they won't admit it, but only North America had an issue with these engines.

 

[SC Maintenance]

A few years ago I've read a Machinery Lubrication article about the relationship between oil viscosoty, HTHS, and contaminants. The jist of was that a motor oil with higher HTHS can keep small particles better in suspention and minimize wear than thin oil. Since then, especially in GDI and T-GDI engines, I try to run oils that have a HTHS of at least 3.5. Soot alone killed so many GDI and T-GDI engines due to the owners running 0W-20 and 5W-20 oils in them for an extended period of time. A lot of the time, even becore the soot manages to stretch the timing chain, it uaually gets the rod bearings first. Just ask Hyundai what happend with their Theta II engines. Nope, they won't admit it, but only North America had an issue with these engines.

They had issues elsewhere also, but I don't doubt that thin oil certainly didn't benefit the situation.

South Korea Indicts 3 Hyundai Executives Over Theta II Engines

South Korean prosecutors raided the offices of Hyundai in February and removed large boxes of materials in a search for evidence of concealing defects and waiting too long to order recalls.

www.carcomplaints.com

 

[dubber09]

Like if you were 5?
Then imagine very little sump and how soon do you think oil will degrade. On the other hand, imagine infinitely large sump and how long it'll take to degrade.
You pee in a toilet or you pee in the ocean.

 

[Vitamin Yoda]

They had issues elsewhere also, but I don't doubt that thin oil certainly didn't benefit the situation.

In the case of Hyundai Theta II and Lambda II, running higher HTHS oil is a bandaid.

 

[racer12306]

My shop says 1000km per liter.

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.

 

[Hall]

Then imagine very little sump and how soon do you think oil will degrade. On the other hand, imagine infinitely large sump and how long it'll take to degrade.
You pee in a toilet or you pee in the ocean.

That analogy is pretty good. Just because the sump is bigger doesn't mean the oil is using more oil, it just has more to circulate.

 

[Snagglefoot]

Chevrolet displayed a liking of sump capacity as they changed the design of their LS and LT V-8 engines. They started with 5 quarts, moved to 6 quarts and when the LT came out they upped it to 8 quarts.

 

[IndyIan]

Chevrolet displayed a liking of sump capacity as they changed the design of their LS and LT V-8 engines. They started with 5 quarts, moved to 6 quarts and when the LT came out they upped it to 8 quarts.

Probably other than excessive short tripping and cold idling, there's no downside to a larger sump and lots of benefits? My 300 kingquad takes about 4L and my 40hp tractor takes 8L so they have lots of oil for their displacement and hp. The kids do more riding on the Atv now so it gets plenty warm everytime it get used these days...

 

[Shel_B]

There's a lot of different tangential conversations about this. But the simplest reason is modern oil is a detergent which holds contaminants in suspension. There's simply more volume to hold contaminants, and more total detergent.

I imagine sump size of an engine has more to do with engineers balancing thermal efficiency of the engine and expected heatsoak.

It may also be indicative of how much space is available for the sump.

 

[Marcozi]

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

 

[Vitamin Yoda]

I imagine sump size of an engine has more to do with engineers balancing thermal efficiency of the engine and expected heatsoak.

When vehicles come with engines that have small sumps (look at Honda 1.5L T-GDI with four quarts), it's because the manufacturer wants to artificially create a low cost of ownership at the expense of reliability. That engine is a know fuel diluter and soot manufacturer. If the oil is not changed often enough, it will eat its own bearings, and the turbo's as well. A six quart sump would have helped that engine greatly.