[its_ethan]

What if there's an efficiency in engine design by placing the filter in the middle that leads to a +2mpg improvement for the driver? Or that it fails, on average, 22k miles later into it's life? Not all hard-to-repair-yourself designs are malicious...

[csours]

If it is a part with a regular maintenance schedule, it should be designed for maintainability.

Most maintainability conflicts come from packaging and design for assembly.

Efficiency more often comes into conflict with durability, and sometimes safety.

[its_ethan]

Right but what I'm getting at is that there can be tradeoffs that might make designing for maintainability mean optimizing for something less important to the end user.

Do you optimize an engine for how easy it is to replace a filter once or twice a year (most likely done by someone the average car-owner is already paying to change their oil for them), or do you optimize it for getting better gas mileage over every single mile the car is driven?

We're talking about a hypothetical car and neither of us (I assume) design engines like this, I'm just trying to illustrate a point about tradeoffs existing. To your own point of efficiency being a trade with durability, that's not in a vacuum. If a part is in a different location with a different loading environment, it can be more/less durable (material changes leading to efficiency differences), more/less likely to break (maybe you service the hard-to-service part half as often when it's in a harder to service spot), etc.

[manquer]

Only TCO matters, that is the efficiency you actually optimize for, ie dollar per mile[1]not miles per gallon.

If the car is going to need to be in shop for days needing you to have a replacement rental because the model is difficult to service and the cost of service itself is not cheap , that can easily outweigh any marginal mpg gain .

Similarly because it is expensive and time consuming you may likely skip service schedules , the engine will then have a reduced life, or seizes up on the road and you need an expensive tow and rebuild etc .

You are implicitly assuming none of these will change if the maintenance is more difficult , that is not the case though

This is what OP is implying when he says a part with regular maintenance schedule to be easily accessible.

[1] of which fuel is only one part , substantial yes but not the only one

[quickthrowman]

> Only TCO matters, that is the efficiency you actually optimize for, ie dollar per mile[1]not miles per gallon.

You’d be surprised how few people actually consider TCO when looking at vehicles, the amount of people driving Jeeps and Audis and similar vehicles that depreciate 60-70% in 5-6 years blows my mind, I just assume anyone driving a car like that hates money.

I bought a RAV4 for $32,000 in 2021, a co-worker of mine paid just over $60k for a Jeep Grand Cherokee 4xe the same year, and the model years are the same. 5 years later, my car is worth more than his (around 22k, his is 18-20k), he ate over $40,000 of depreciation in 5 years, that’s just insane to me.

[its_ethan]

I'm just gonna copy and paste a response to another similar comment:

The point that I am making (obviously, I think) is that tradeoffs exist, even if you don't think the right decision was made, your full view into the trade space is likely incomplete, or prioritizes something different than the engineers.

Putting some random number of hypothetical mpg improvement was clearly a mistake, but I assumed people here would be able to get the point I was trying to make, instead of getting riled up about the relationship (or lack thereof) of oil filters and fuel efficiency.

[manquer]

I did read that before commenting, to be clear - the specific nature of your proposed optimization is not important and I took your premise to be true ie it will improve fuel efficiency and therefore save some money.

—

In general, the point was it is not operational efficiency in ideal conditions alone and serviceability is an important component because it can add to the overall cost of ownership significantly and individual car owners (in comparison to fleet) are typically poorer in factoring this in their buy decisions.

——

It comes down to numbers , if the proposed change, results in 10% improvement probably not worth it, 10x then definitely so .

I.e will the car become 22 MPGe or 200MPGe . Larger the gain more trade-offs like serviceability or life expectancy all can be sacrificed.

hybrids costs more upfront (both sets of expensive components - transmission/motor +engine/battery) but still work if driven enough miles, as the gain in efficiency makes up for the upfront.

Exact number of that miles is localized to you and me - depends things like tax difference including tolls, gas prices, MPGe diff, electricity prices, interest and purchasing power of currency other consumables costs like tires and so on.

[ww520]

If the engine failed due to missing oil change because of the difficulty, the whole car is gone. The waste in cost, material, and environmental impact far outweighs the savings in 2mpg improvement.

[its_ethan]

Glad to know in this hypothetical car scenario the owner decided to not get an oil change leading to the total loss of the vehicle. That seems very realistic and definitely something that car designs should be optimized around.

Or, we consider that 2mpg across 100,000 cars can save 3,500,000 gallons of gas being burned for the average American driving ~12k miles per year. And maybe things aren't so black and white. You're argument, in this hypothetical, is that negligent car owner who destroys their car because they're choosing to not change the oil is worth burning an extra 3.5millon gallons of gasoline.

[bena]

To be fair, you are constructing an entirely hypothetical car scenario where oil filter placement leads to a 5-10% increase in fuel efficiency.

We're already in the land of the fucking ridiculous. Let's have fun with it.

[its_ethan]

I'm using this hypothetical to illustrate the point that: tradeoffs exist, and that you (we) may not have full insight into the full complexity of the trade space that the engineers were working with.

Putting some random number of hypothetical mpg improvement was clearly a mistake, but I assumed people here would be able to get the point I was trying to make, instead of getting riled up about the relationship (or lack thereof) of oil filters and fuel efficiency.

[bena]

And he's using his hypothetical to illustrate the point that: even while some benefits may exist, there are other considerations besides one measure of efficiency.

That's the point you're not getting. People get your point. They're just pointing out that sometimes the juice isn't worth the squeeze. And for something that needs to be regularly accessed, it's better for it to be accessible than strictly optimal.

And during the whole debacle, you've demonstrated that you don't have much insight to the trade space at all. And you're so dead set on "not being wrong" here that now you're accusing everyone around you of being riled up. We're chill, dude. We're starting to worry about you.

[its_ethan]

> there are other considerations besides one measure of efficiency

Bruh that's literally what I was saying? Instead of how efficiently can you replace a filter in an engine, another benefit might exist instead. Said another way, maybe the "juice" gained from redesigning a fuel filter system instead of using an existing one form another car wasn't worth the "squeeze" of cost and development for the company.

Kinda feels like maybe you (the majority of replies to my original message) didn't get the point, and instead took this as some literal suggestion that I think engines need to have filters in certain spots.

The fact that so many people took this as literally as they did, and seemingly chose to ignore the underlying message of "hey maybe consider tradeoffs exist" makes me start to worry about you too.

[carefree-bob]

This is like saying you can get a 10% improvement in battery life by changing where you position the RAM on your motherboard.

There is just no universe in which placing an oil filter in one location or another is going to make such a difference. You'd have to mount it completely outside the engine, say sitting as a cylinder on top of the hood, and even there you are not going to get a 2mpg improvement.

[its_ethan]

Sorry we're talking about a hypothetical car engine, and as an analogy to software development. I'm not an expert in designing car engines like you, but acting like this example being not fully realistic is some kind of "gotcha" for the point I'm making is really frustrating.

The point that I am making (obviously, I think) is that tradeoffs exist, even if you don't think the right decision was made, your full view into the trade space is likely incomplete, or prioritizes something different than the engineers.

Based on the replies, saying there's a hypothetical 2mpg improvement to be had was a mistake, everyone is latching on to that like there's some actual engine we're investigating.

[Arch-TK]

You made a "well actually" comment in which you demonstrated your lack of knowledge on the topic, _and_ stated a truism which didn't apply to the thing you were replying to.

Yes, I'm sure most people on this website have ran into seemingly bad design choices which made sense once they knew more context. But that doesn't mean that all bad design choices are like this.

Specifically dumb oil filter placement is an example of such a case where the _only_ legitimate justification is design cost saving for the manufacturer (re-using an existing design meant for a different car).

You can maybe argue that saving on design costs (and I guess also re-tooling costs) is a saving that gets passed onto the consumer. But that consumer is unlikely to feel like they're saving much money when cars depreciate faster than ice cubes in the desert, and when their oil change is 2+ times more expensive every 6 months. Really that cost savings will only really benefit the manufacturer (well, at least until they tarnish their reputation).

[its_ethan]

> Yes, I'm sure most people on this website have ran into seemingly bad design choices which made sense once they knew more context. But that doesn't mean that all bad design choices are like this.

I'm literally just saying the yin to this yang. Just because you run into a design that feels malicious doesn't mean that it always is.

Again, sorry for the sin of trying to make an analogy/example of something I'm not an expert in. You can rest easy at night knowing I'll never do it again.

You also pretty neatly laid out how re-using an existing design meant for a different car leads to some benefits to the end customer. Sure the full cost savings don't ever make it to the buyer, but there's still net wins in not spinning up new manufacturing processes (as you say). So I'm not sure why you're coming at this so combatively? Because I dared float the idea that maybe it's an engine efficiency thing we're unaware of, instead of part re-use cost/lead time efficiency improvement? Again, sorry for stepping outside of my lane...

[rixed]

Option 1: "I am so much smarter than these stupid engineers"

Option 2: "Certainly, I do not understand the various trade offs that led to this design"

I wished at least in software tech circles there would be more of option 2 kind of thinking.

[Arch-TK]

Option 3: "Engineers have discussed this at length and all agree that the only justifications for this design are based in extremely short-term thinking."

[carefree-bob]

No, the point is that the GP statement missed the point. Say we hear about a company laying off 10% of workers, and someone says "What if they needed to lay off those workers in order to meet their HIPAA obligations and protect user privacy?" Now clearly that would be an argument that is either bad faith, or just spectacularly uninformed. We do not then go on to discuss the relative importance of HIPAA compliance versus employment. The reason companies lay off workers is because of a decline in market demand or efforts at cost cutting. That is the reason. It's not to help the environment. It's not to protect customer data. It's not because this is the year of the Pig. Anyone who makes those arguments should get responded to in a way to clearly points out it is a specious argument.

The reason why automakers place serviceable parts in bad locations is due to either incompetence (If you are, say, Bentley) or malicious design (almost everyone else) -- e.g. they do not prioritize serviceability. Car makers really hate that ordinary people can repair their own vehicles. There were proposals in the 1960s to try to lock shut the hood so that car owners wouldn't be able to open it and service the cars on their own. Hyundai just announced that they will not allow car owners to retract their own parking brakes when they want to replace brake pads. You need a login with a website and prove that you are a professional mechanic before you can retract your own parking brakes. This is done, ostensibly, for "cyber security" reasons. But the real reason is that Hyundai does not want people to be able to service their own cars, they want you to take the car to a dealer. They also are not fans of independent mechanics, they would prefer if everyone that touched the car had a business relationship with Hyundai and was under contract with them. The fact that you can work on your car is an endless source of pain for manufacturers, and when they repeatedly make it hard to work on your car, or try to lock down parts so that you can't pull an old seat heater from the junkyard and use it to replace your own failed seat heater -- that is all part of the war on independent repair.

So what should be discussed is the environment of hostility to serviceability, everything from insisting that transmission oil is "lifetime" to forcing you to pay money to the manufacturer if you want to read the data from your sensors, or making it extremely hard to do simple things like changing a headlight or replacing a battery. All of that is part of the same issue, which is hostility to end user repair. It has nothing to do with improving gas mileage, or ending world hunger, or celebrating the Year of the Pig. These are all equally specious arguments.

[rixed]

Serviceability by owner is less and less important as fewer and fewer owners actually do maintenance themselves, though.

[Terr_]

Even if 100% of owners choose to pay someone else to do it, they are still benefiting from the user-serviceable standard.

First, anything serviceable by the owner is also accessible to a local garage or independent repair shop. That means a competitive market for those owners, rather that being stuck paying extra to a local monopoly or to a rent-seeking manufacturer.

Second, it makes long-term repairability of the product much easier, things don't just suddenly become irreparable because the manufacturer closed down their "unlock codes for trusted affiliates" site. Their asset retains more of its value.

There are things which provide value even when nobody uses them.

[its_ethan]

ok, glad you seem to have everything figure out so definitively

[Arch-TK]

We don't have magic oil filters which last even 22k miles. You should be replacing them every 6 months / 6k miles, or 12 months / 12k miles depending on your risk tolerance (some people suggest even half my short interval).

Anyone who actually drives their car regularly will be doing an oil change at least twice a year. If an oil change takes more than 30 minutes of actual labour time of an inexperienced mechanic, it's going to be a serious financial burden which will likely outweigh any 2mpg improvement.

[bluGill]

> We don't have magic oil filters which last even 22k miles. You should be replacing them every 6 months / 6k miles, or 12 months / 12k miles depending on your risk tolerance (some people suggest even half my short interval).

We do - they are just a lot bigger.

You should replace the oil filter when it is no longer filtering. Replacing it early is a pure waste of money. Unfortunately the tests of do you need to change the oil filter is more expensive than just replacing the filter so just replace it before it can possibly be clogged is the right answer. Generally the manufactures recommendations are correct and you should follow what they say unless you have lab results that say otherwise.

[Arch-TK]

> We do - they are just a lot bigger.

Yeah, of course, but I am not aware of any regular car which comes stock with such filters.

The point was really that lasting 22k miles longer than stock would be an unrealistic improvement for a filter for a normal car.

> You should replace the oil filter when it is no longer filtering.

I was specifically referring to manufacturer recommendations. Of course they're conservative, they also have to account for engine wear.

And yes, you are right that ideally you'd test. Although testing the filter from what I've seen is destructive, and there's a nontrivial turnaround time.

I'd disagree that following manufacturer recommendations is a waste of money though. As you say, testing is _more_ expensive. Engine damage is even more expensive. Replacing the filter on schedule is the economical choice.

It might be strictly a waste of resources, but that's a separate concern.

[bluGill]

Cars are fairly easy to service, and and so get shorter oil change intervals. industrial engines often get bigger filters. A thermoking refrigerator has a massive filter for a tiny 2 liter engine (at least the one unit I've seen - which was at least 30 years old, I don't know what the latest do)

[bluGill]

Follow the manufacture recomendations. it sounded like a recomendation to replace more often. Maybe we are in agreement?

filter test can be inferred from flow rate and oil analisys. Destructive testing is best if you must know - but also not helpful.

[its_ethan]

I'm just gonna copy and paste a response to another similar comment: The point that I am making (obviously, I think) is that tradeoffs exist, even if you don't think the right decision was made, your full view into the trade space is likely incomplete, or prioritizes something different than the engineers.

Putting some random number of hypothetical mpg improvement was clearly a mistake, but I assumed people here would be able to get the point I was trying to make, instead of getting riled up about the relationship (or lack thereof) of oil filters and fuel efficiency.

[Arch-TK]

You can also read my reply in my other comment.

But to keep it concise: The core problem is that you are stating a truism in response to a famous counter-example to specifically that truism. The other problem being that you are stating a truism which everyone else is already familiar with.

[its_ethan]

Given how many people have seemingly jumped on misinterpreting the truism as me making some claim of a specific fuel efficiency improvement, I'd disagree with people being already familiar with it.

To be concise as well: it's been duly noted by me that contributing to a conversation by attempting to bring in nuance is not always well received when you make up a hypothetical for a topic people are very touchy about.

[quickthrowman]

> You should be replacing them every 6 months / 6k miles, or 12 months / 12k miles depending on your risk tolerance

You should be replacing your oil filters based on the manufacturer’s service schedule, there’s no rule of thumb. Look at the service manual, my car has the filter change scheduled every 10,000 miles.

[1970-01-01]

Except..there is never such reason. They can put the filter anywhere in the pipeline. Some even have it exactly where it should be: https://www.ifixit.com/Guide/2013+Subaru+Legacy+Oil+and+Oil+...

[eszed]

Mazda has historically been very good at designing for repairability. My (latest) Mazda is ten years old, so I cannot verify any model later than that, but it's one reason I've been brand-loyal for decades. The 2015 CX-5 puts the oil filter right next to the drain plug, slightly recessed (for protection, I assume), but with ample clearance around it for tool and finger access. It's the best thought-out oil filter location I've ever seen; I cannot think of any possible improvement. The advantage of that, over Subaru's choice, is that the oil in the filter can only ever spill into your drain pan (or I guess the ground, if you're a numpty), never into your engine compartment.

[datsci_est_2015]

I’m no mechanical engineer, but I would assume those extreme tradeoffs occur more often when repairability is not prioritized from early iterations. I.e. “boss we’re 90% into the design cycle why are you bringing up the position of the oil filter now?”

There’s definitely a programming equivalent as well…

[PunchyHamster]

That is fine if you are say building a race car that will be essentially rebuilt anyway in between races, or in general where 0.1% extra performace/less weight from non-repair-friendly placement might be worth it.

Not for normal car

[batisteo]

Most cars sold in the US are not aerodynamic so it seems a couple of mpg isn't the focus anyway

[carefree-bob]

The US is filled with bubble cars like everywhere else. There isn't really much difference between cars across the world. Well, China is unique with like 100 automakers all searching for customers, but for most of the world, it's Toyota, VW, Hyundai/Kia, Stellantis, GM, Renault/Nissan, Ford as the top global producers and they sell everywhere. Sure there are some special models in local markets, but those are mostly rebadged versions you can get elsewhere.

Fun Fact: Along with the "Bees are disappearing" scare, which was just measurement error, there has been an "insects are disappearing" scare, due to the fact people's windshields are not covered with bugs like they used to be. However that is because cars have gotten more aerodynamic so fewer insects are hitting the windshield.

[cableshaft]

> However that is because cars have gotten more aerodynamic so fewer insects are hitting the windshield.

According to this research the opposite is true:

"The survey of insects hitting car windscreens in rural Denmark used data collected every summer from 1997 to 2017 and found an 80% decline in abundance. It also found a parallel decline in the number of swallows and martins, birds that live on insects.

The second survey, in the UK county of Kent in 2019, examined splats in a grid placed over car registration plates, known as a “splatometer”. This revealed 50% fewer impacts than in 2004. The research included vintage cars up to 70 years old to see if their less aerodynamic shape meant they killed more bugs, but it found that modern cars actually hit slightly more insects."

Source: https://www.theguardian.com/environment/2020/feb/12/car-spla...

[9rx]

> Along with the "Bees are disappearing" scare, which was just measurement error

Or fixed? The suspected cause at the time was pneumatic planter dust-off and addressing that was as simple as adding a baffle to direct the dust to the ground, so it was quickly adopted once identified.

[coeneedell]

https://en.wikipedia.org/wiki/Decline_in_insect_populations?...

Um I’m pretty sure that’s not the only evidence for insect population declines.

[0x457]

I think oil filter located somewhere sinful usually in cars that are aerodynamically sound.