The internet is full of aftermarket companies trying to sell you products to solve your automotive issues. They’ll tell you there’s something wrong with your car, and they’ve got the product to fix it. Banks Power likes to go a little bit further, though. They don’t just tell you what’s wrong—they’ll show you! It’s then up to you to decide on what you’re seeing.
Previously, Banks Power did a great job explaining what’s wrong with the Cummins 6.7-liter diesel. They showed us how a single nut can get ingested into the engine, causing terminal damage in many cases. Their video showed us, with specific examples, how corroded or weak grid heater components were causing all the trouble.
Earlier this week, Banks Power returned to YouTube to show us an issue with the 6.6-liter Duramax L5P engine, as used in the Chevy Silverado HD and the GMC Sierra HD. We’re told that GM’s oil pan design is trapping dirty oil in the engine, even after an oil change! The video presents this as an “engine killer,” which seemed pretty drastic to me. Let’s examine what’s going on.
Old Oil
Banks Power develops a wide range of accessories. In regards to GM’s Duramax-powered trucks, it has developed a range of upgrade parts designed for heavy-duty users. To this end, the company produces upgraded differential covers, transmissions pans, and oil pans. They’re designed to help keep the vehicle’s vital fluids within an acceptable temperature range during sustained high-load situations like towing, achieving this through the use of cooling fins and greater fluid capacities.
However, it was during development of the Duramax oil pan that the team found something curious. “There’s a quart of dirty oil trapped inside your engine,” says Erik Reider, special projects lead at Banks Power. “No matter how many times you change your oil, it’s not coming out,” he explains.
The cause of the problem is relatively simple. When GM designed its stamped steel oil pan, it had to make provision for the sump plug. Since the stamped steel is very thin, it doesn’t have enough thickness for the plug to thread into. To get around this, GM used a weld nut. It’s basically a little threaded nut that attaches to the sheet metal and provides enough thread engagement for the sump plug to work properly.
The thing is, the weld nut sits proud inside the sheet metal oil pan, by around 3/4 of an inch or so. Thus, it creates a lip, so that the the oil pan outlet is not actually at the lowest point of the sump. This means that when draining the oil, some oil pools around that lip without fully draining out of the engine.
It seems wild that the stock pan would work like this, which Reider readily admits. “You’re skeptical,” he says. “There’s no way that GM would allow this dirty oil to be trapped inside the pan for the life of the vehicle.” However, he has a way to prove it—Banks Power 3D scanned a stock oil pan and made a similar part in clear plastic. This would allow the engine to be filled with oil, and then drained, to demonstrate roughly how much oil remains in the engine after draining it.
[Ed Note: This type of oil pan drain plug design is pretty standard stuff.
Above is a look at my Pontiac Aztek’s new (aftermarket) transmission oil pan. -DT]
Between the oil pan and the oil pickup tube, around one quart (0.94 liters) — or 10% — of oil remains trapped in the engine during an oil change. That’s quite a bit of old oil to be left behind. In particular, because of the weld nut, the oil level remains high enough to stop air reaching the oil pickup, which leaves some oil trapped in there as well.
“I think disturbing is the right word for this,” says Reider, noting the amount of oil that was still left in the pan. “This means that if you have the stock pan, you’re stuck with a quart of dirty oil, literally forever,” he says. “It’s got metal debris, soot, it’s been oxidized, aerated, none of this is good for your engine.”
You’d think that any oil remaining in the pan is effectively diluted by the ten quarts of new oil that would be put in during an oil change. However, this does mean you may not be draining out stuff like metal particles, which instead may stay behind in the sump. That’s not ideal. At the same time, if you’ve got a significant quantity of sizable metal particles in your oil, you’ve probably got other problems, anyway.
It’s worth noting that Banks Power made this video for a reason—it’s effectively an advertisement for their own oil pan for the Duramax engine. Their design places the drain plug at the absolute bottom point of the oil pan. With no appreciable lip, it allows virtually all the oil to drain out of the engine during an oil change. It’s also got a magnetic oil plug for attracting any ferrous metal particles that may end up in the oil. The design also allows the oil level to drop beneath the level of the oil pickup when fully drained, allowing that part of the oil system to drain out, too.
The redesigned oil pan also has a greater oil capacity versus stock for increased thermal mass. With two extra quarts of oil in the engine, it takes longer for the oil to heat up to critical levels. “It holds two more quarts of oil over stock, which slows heat saturation thanks to the increased thermal mass,” says Reider.
Of course, that’s not all that matters, though. “Once all of that oil is hot, it’s hot,” explains Reider. “What really matters is how you reject that heat. ” To that end, the pan also features large fins to improve convective cooling—it’s designed just like a heatsink you might find inside your computer. The idea is to help keep oil temperatures lower during heavy-duty running, such as when towing uphill. By keeping oil temps below set thresholds, the Duramax ECU will allow the engine to keep running at maximum output. Banks Power isn’t the only game in town, either; as covered by Diesel World, aftermarket manufacturer PPE has an oil pan of its own designed to similar ends.
Is this a problem that requires aftermarket parts to solve? I’m not necessarily convinced. As covered by repair shop ProSource Diesel, the L5P has a pretty good reputation, mechanically speaking. It’s been in production since 2017 and hasn’t had any major recalls for oil system issues or the like. Ultimately, if this “trapped” oil were a big problem, we’d see lots of evidence by now—owners complaining of sludged-up engines, or common problems with bearings and valve trains and the like. Ultimately, Banks started developing this part to improve cooling—solving the oil drain issue was just a nice bonus that makes the part a lot more attractive.
From my professional standpoint as an engineer, two things are true. Yes, the stock oil pan design does leave some oil trapped in the sump after an oil change. At the same time, this isn’t necessarily a big deal. Obviously, it’s ideal to drain all the oil, particularly if there is any particulate matter in it. But for a properly-running, undamaged engine… leaving a quart of older oil in the sump isn’t going to particularly hurt anything. After all, the engine was running just fine on that oil immediately before the change! It’s also a little disingenuous to say that the oil is “trapped forever.” You’re not left with one single bad quart for the life of the engine. That quart of oil is mixed with the new stuff as soon as the oil pump runs the first time. It’s just that on each oil change, some of your current oil is left behind. And as for particulate matter, capturing that is what the oil pickup screen and especially the oil filter are for.
I’m not the only one that thinks this way. Head over to the r/Duramax page over on Reddit, and many owners and techs feel the same way. “This video is a perfect example of scare tactics,” says Kennel_King. “If that quart of oil being in there was that big of a deal, these engines would be failing left and right.” Others note that this story has played out with previous generations of Duramax engines before, too, which similarly trapped some oil in the sump. “My ’01 LB7 is at 1.48 million miles and I’m about to tow across country,” says tuskenDMAXer. “Still got the original oil pan for the original engine and rear differential cover for the original gears and bearings, even though Banks says they’re no good.”
If you’re changing your oil regularly as you should be, that last bit of oil will be diluted by the new stuff each time. The fresh oil will do its job, and it won’t be unduly harmed by the quart or so remaining from before. You can buy an aftermarket oil pan if you really want one, but I wouldn’t unduly worry about it.
Image credits: Banks Power via YouTube screenshot
While I agree that the amount of leftover oil is trivial, it seems possible to me that having a reservoir at the lowest point in the engine would accumulate debris that couldn’t be drained out.
If it’s neither drained nor sucked up into the pickup tube, does it matter?
My suspicion is that even if the pan can drain completely, due to oil viscosity and other factors like sludge accumulation that debris isn’t going to come out anyway.
Are you guys not rinsing out the old oil with a garden hose in the oil fill before putting new oil in?
I thought squirting a little bit of Dawn dishwashing soap up in there was the preferred method for cleaning out the pan?
People think an oil change replaces every last drop of oil. Using an extractor leaves about a cup of oil in the GTI and that’s enough for some people to lose their minds over. Marketing scare tactics to sell a $500 oil pan.
Wow, the fins on that Banks oil pan. It has indeed jumped the shark.
With any aftermarket upgrades like this, my response is: if it makes you feel good buying it, that you’re treating you engine extra nice, by all means do it. It’s a small price to pay for happiness.
Currently having this debate with my son, who wants to buy a “cold air” intake for his car.
If price is no object, I’m sure every part on a production vehicle could be improved upon. Whether it’s necessary and worth it is the question.
Hi!
I design intake systems for OEMs. Unless your son’s cold air intake is the result of a dozen iterations of CFD and design which is then validated by a-b-a testing on a calibrated flow rig, it’s is wildly unlikely to be as effective as the OEM intake (which is also already a cold air intake).
Maybe he’ll get lucky and buy a car engineered by blind morons who hate free power and are employed by a company that has no emission, power or economy targets, but chances are they did their job properly.
CAN I GET AN AMEN?!
Thanks Captain! It’s awesome to get input from an expert.
I’m a mechanical engineer and totally get what you’re saying. Unless the intake filter system was indeed the bottleneck in the whole system from air inlet to exhaust tip, the aftermarket intake would likely do nothing and possibly make things worse. And these aftermarket systems look more like hot air intakes to me, big filters pulling hot air from under the hood, instead of from a duct in front of the engine.
I keep telling him that they design and build things pretty well at the factory and he has to appreciate all the engineering that goes into every single part.
He’s 17, his car has a turbo, and is only interested in hearing the turbo wind up and chatter, sigh… I was stupid like that and put a free flow exhaust on my first car only to get headaches from the noise.
So, understanding that it’s a balancing act (you mention emission, power, and economy). How much power is sacrificed for the other things? If Johnny down the street doesn’t care if it’s noiser, thirstier, pollutier are there really much gains to be had even with a tested intake that focuses solely on power assuming they make no other modifications?
Fortunately reducing emissions, improving economy and increasing power all benefit from reducing the pressure drop through the intake. We reduce the pressure drop by optimising flow (reducing internal aerodynamic drag) and optimising filter utilisation (basically making sure the flow is uniformly spread over the whole filter area, this is the tricky bit and the thing the aftermarket is terrible at).
Noise emissions can be a problem, but you design out features that add resonance, design in stiffness to the housing (this can add a bit of cost, but plastic is cheap) and if you have a particular problem with a frequency you add in a resonator to kill it (more cost, but it doesn’t affect flow).
So none of that has a negative effect on power.
Of course we’ve only sized it for the most powerful engine for that vehicle platform, but I’ve seen the engine dyno plots of one of my systems compared to a selection of aftermarket systems and most made less power, and none were higher. That was with a cooling fan blowing at the intake too, installed in a car they’d do worse.
I wish we’d done a run with no filter at all to give us more data, but the whole thing was done during a gap between projects, rather than as science.
I know we’re pretty harsh on “stupid” things around here but I say if it’s not doing serious harm and it gets someone excited about their car and mods, etc. Then it’s still a good thing. Cold air intakes included. Just make sure he keeps the old one for when he changes his mind.
I bought a Miata in 1990. Over the next 10 years, I replaced a whole bunch of things like air intake, header, exhaust in an attempt to squeeze out a bit more power. Fortunately I kept them all because as the aftermarket parts failed, the car slowly returned to stock. When I recently installed the complicated factory intake, and with 30 years of wisdom, I realized how much better the car was as the clever engineers designed it.
There is a similar debate with 7.3 Powerstroke owners and whether or not you should change your HPOP (high pressure oil pump) oil. It’s been explained on the site before but 7.3s use oil driven fuel injection. Basically there is an engine driven oil pump which pressurizes oil and that high pressure oil is used to push fuel into the engine through the injectors. Basically the injector acts as a plunger and the oil is pushing the back of it. So 7.3s have a few quarts of oil always trapped up in the high pressure oil pump and the lines to the injectors when you change the oil. A lot of people say the oil needs to be replaced in the HPOP, but that has since been written off as nonsense.
You might sometimes see an ad for one with high miles but the seller will assure you it’s fine because they changed the HPOP oil.
You know, I’ve never fully drained my gas tank either! That last gallon left over from the first time it was filled must be so close to ruining my engine by now! /s
When I breathe out I’m not sure I’m emptying all of my lungs.
There must be like a pint of bad air in there full of fibre glass and tyre particles.
Isn’t this something that basically any car that has an oil cooler does, much moreso?
Lots of fluids in cars are like this. When I drain the CVT on my Subaru, only like 60% of the fluid capacity actually drains out (I can’t remember off the top of my head). But it’s to be expected.
Draining the coolant out of my ’65 using the petcock, and you are only able to get like 80% of the coolant out.
If these things matter to the service you are doing, the manufacturers will typically perscribe a flush based process.
Many stamped pans with a welded nut inside position the hole at an angle, or even at 90 degrees, in order to avoid this problem.
Also, you really don’t want to remove ALL of the oil when you change it, otherwise you might do damage when you restart.
I would assume that cast aluminum pans don’t have this problem.
(Laughs in rotary) Between passages all around the engine housing of a Wankel, associated oil coolers, etc. A standard oil+filter change only replaces about half. 10% is nothing to worry about. Extra oil cooling is nice, though.
Oil capacity:
Source: 2004 Mazda RX-8 Workshop manual, section 01-11 (Engine Lubrication)
Every engine I have ever touched has always had old oil left, nothing new here. And 1 quart of the 11 is probably the average considering a car that takes about 5 quarts probably takes over a 1/2 quart more when completely dry. This is a classic case of making numbers say what you want them to say.
When I want to drain the most on an engine I let the engine do one crank (not start) after I drained. I also add unused oil from the last oil change to flush out as much of the old oil as possible. Then may stick an oil vacuum in the drain plug and oil filter housing. Still costs only a fraction of whatever they want for their oil pan.
It’s quite common with oil pans to retain some oil and, with the large capacity of oil these engines take, even less of an issue than it is with everything else that doesn’t have problems. My pickup is on the side, so I jack it up from the other side to drain slightly more thoroughly. I don’t think it’s actually necessary to do so, just that I only have to jack it up and block it on one side to get underneath, so I might as well choose the offside. So much about what car accessory companies sell is unnecessary overkill to paranoids who enjoy throwing away money or straight up snake oil. At least this is functional, if unnecessary.
Another reason this is kind of stupid?
“There’s a quart of dirty oil trapped inside your engine,” says Erik Reider, special projects lead at Banks Power. “No matter how many times you change your oil, it’s not coming out,” … “It’s got metal debris, soot, it’s been oxidized, aerated, none of this is good for your engine.”
They obviously want to imply that it’s the exact same quart of oil that always left in the engine.
Clearly, in reality, this is a high school math mixing problem.
Any given quart is only 10% after one change, 1% after two changes, 0.1% after three, etc., etc.
It will be okay.
It should be obvious why the guy selling the “solutition” to this “problem” suggests otherwise.
1 qt at < 10%? Big whoop. I think 3 or 4 quarts are left in the torque converter when I change the AFT on my van (gravity draining with transmission pan removed.
Nah… we want to keep some of the old oil in the pan. It’s good to do that!!!
It helps ‘season’ the new oil which helps the engine last longer!!!
/jk
I usually add a pinch or two of salt. Got to get the seasoning just right.
I hear that you add salt for more mileage and add pepper if you want more horsepower… LOL
If they’re worried about this, wait until they hear about the 7.3 and 6.0 Powerstroke. Both have a separate reservoir for the HP oil pump that holds about a quart and does not drain during oil changes. On the 7.3, it does have an access plug that you could probably get a vacuum pump in there to change it if you really wanted to but the 6.0 reservoir is inaccessible without removing many other components first. But when an oil change calls for 15 quarts of oil, that extra quart of the old stuff really doesn’t matter once it gets blended in with the fresh, new oil.
I wouldn’t own one of those ugly trucks, so the specific point is moot.
However for that much oil to remain is mildly concerning. Yes, that’s what the filter is designed to address, and the pickup tube has a mesh screen. But I’ve also seen a lot of damage occur in very little time from seemingly very innocent particulate.
So if I had an oil pan that left that much oil behind, I’d probably use a suction tool with a U-shaped straw/nozzle on the end to slurp up as much of the remaining amount when doing a change. Seems a lot less involved and cheaper than a new oil pan. But if something happened to a factory pan, then I might consider an aftermarket option like this.
You say “that much” like 10% or one quart is much at all. You’d be hard pressed to find many cars that don’t retain at least 10% old oil after a drain. 10% of five quarts is only half a quart, and that is a very average amount.
If you have significant particulate in your oil, that’s why you have an oil filter that filters all oil before it gets to the bearings or lifters.
You’re essentially repeating what I already said.
You’re essentially repeating what I said, that you’re replying to. *shrug*
Someone can feel free to correct me if I am wrong, but the entire volume of oil doesn’t immediately return to the pan the second an engine is turned off. If a small volume of old oil was a problem, wouldn’t you need to let the vehicle sit for a prolonged period prior to changing the oil? Customers of quick oil change establishments would be destroying their engines with their impatience. Merely driving the vehicle into the service bay would move engine-killing used oil out of the pan and into other parts of the engine.
I’m not very familiar with Banks Power, but their claim seems obviously ridiculous to the point where I would question anything they say. This kind of kills their credibility.
It came from the internet so it’s got to be true.
Ideally you would drain the oil pan and then run the engine for a minute so the oil pickup only gets air. That way you really empty all the old oil out of there.
While the old oil may not be an issue, the other benefits (better oil cooling and greater oil capacity) would be enough reason for me to upgrade to this pan over the old pan.
But do you need “better cooling”, or will it just take longer for the oil to reach its proper operating temperature?
Good point, For me I wouldn’t need better cooling, but having the engine debris further diluted by extra oil would be nice.
This is why I always start the engine for a minute or two after draining the oil.
Both diesel and gasoline engines. Even my hybrid Toyota.
The turbulence created by all those internal parts spinning is bigly helpful.
It gives the left over oil a chance to drain out. Works every time.
You run your engine without oil? Or just turning it over by hand when it’s draining?
it was a joke
bigly
Ah!
I only do this with my 2-stroke engines. I’ll have to try it with the others.
Yeah, oil changes on a 2-stroke are a real PITA. 😉
lol!
And I should have indicated my sarcasm in the original post.
Sorry/not sorry.
I just leave it running the entire time I’m changing the oil. Really scrubs the engine good.
It is surprising how much is left in that pan, but I agree that it isn’t necessarily a problem. But also agree that it would be nice if more oil drained out. I also think that magnetic drain plugs should be standard.
On most cars I’ve owned, they’ve taken a little bit over 4 quarts of oil. The 5 quart jugs tend to be cheaper than buying 4 quarts. If I historically had better storage locations and was buying the exact same oil every time, I could have just saved the leftover every time until I had enough for an oil change.
Instead after the oil was almost entirely drained out of the car I’d pour about a 1/2 quart of oil in the filler. Usually I’d get a couple more big glugs of dirty oil and then it would run nice and clear.
Was this necessary? No, and probably a bit wasteful even. But the oil pan they are pushing holds an extra 2 quarts, so pouring an extra quart in to “flush” the oil pan uses less oil overall if you think it’s an issue (unless you really want the extra 2 quarts of capacity).
I used to stick old hard drive magnets to my drain plugs. I still Have a few here and there. I think I have one one my air compressor’s oil drain plug too.
Yup burning a qt or a 1/2 qt is a good way to float the hot dirty oil out.
My immediate thought was that all of those particulates left in the residual oil should get caught in the filter if they get stirred up somehow. And if they’re not getting stirred up and are sitting at the bottom of the pan, then they aren’t causing trouble anyways. I guess if it really worries you, you could always drop the oil pan every X number of changes to get the rest of it out.
Good point. Their solution for having to drop the pan to drain all the oil is to have you drop the pan to replace the pan.
Alternately, drop pan, fetch BFH and a hardwood stick (hockey would work well) and divot the pan into a mini sump around the drain plug. Does wonders for venting the frustrations built up reading garbage on the internet.
Do they sell fuelsharks too?
Ask about our new OilShark!!
I’ll buy 3.
Good call. That will triple its effectiveness!
Well the oil pan does have fins.
Something that should be obvious but I didn’t see mentioned in the article is that of course the quart left over is not the same one each time!
It’s more accurate to say that an oil change replaces 90% of the old oil. And the oil mixes up thoroughly each time.
So after five 10k mile oil changes:
90% of the oil is 0 miles old
9% is 10,000 miles old
0.9% is 20,000 miles old
0.09% is 30,000 miles old
0.009% is 40,000 miles old
This is a big nothing burger.
My Viper has the drain plug on the side of the pan. There’s no way all the old oil comes out each time unless you jack the passenger side higher than the driver side. No one does that, it’s ridiculous. There’s just a little bit left each time that mostly gets changed out the next time.
Too late to edit, but 1.5 teaspoons is 30,000 miles old and less than 1 ml is 40,000 miles old under this scenario.
And this is how MacDonald’s does the French fry oil. /s
The jokes on you. They don’t change the fry oil at McDonald’s. They make Grimace bathe in it occasionally so that the fry bits and dead bugs get stuck to his fur.
It’s the Mc je ne sais quoi!
They mention the mixing of that leftover oil with the new oil above the Kennel King reddit imbedded image.
I’m imagining you flipping your Viper onto its driver side and using a giant shake table every time you change the oil. Sounds like quite an adventure.
Not to mention that the new filter that ideally accompanies the oil change will capture any remaining contaminants.
This is a solution looking for a problem (that doesn’t exist)
One thing immediately apparent to me is, that factory oil pan was designed for the front of the truck to be up on ramps with the back end on the ground, which would allow it to drain nearly completely. Also unless you are dissembling the engine and cleaning every part, there will still be old oil left in it every time.
If that was the intention, they should put it in the manual (and maybe they do? I don’t know). Most oil changes are done with a level vehicle, so I’m not sure it was their intention. That said, it would obviously allow more oil to drain and is a simple solution to this “problem”. That said, the annoying part about doing an oil change on a car that isn’t level is having to go back and check the oil level a second time after you’ve leveled it back out.
I’m guessing that might of been part of that, and they probably figured out the difference in quantity left in both ways so so minimal that they just left it like that since it probably cost less to make it this way