“The first model year is the one to avoid,” is the conventional wisdom about when to wait to buy a car and when to pull the trigger. In reality, things can be more complicated than that. Take my BMW i3, which I bought because it was cheap due to it having 135,000 miles on the clock and being the first model-year, 2014. These early i3s suffered from all sorts of first-model-year growing pains, but you know what they didn’t suffer from? Bullshit Technical Cost Reduction (TCR) like removal of a fill-plug, justified via the concept of “Fill For Life” transmissions. Let’s talk about this.
If you pop the hood of an automatic car from the 1990s, you’ll most likely see a second dipstick to allow you to check the transmission fluid quality and level. Move on to the 2000s, and you may have a fill-port on top of your transaxle, along with an “overflow” plug down below telling you when the transmission is full. Check underhood of a modern automatic-equipped vehicle — even an off-roader like the Jeep Wrangler JL — and you’ll see no dipstick at all and no fill port. That’s because modern automatic transmissions are what’s called “fill for life” transmissions.
Basically, the automaker (and transmission manufacturer) decided that, given the driving conditions the vehicle was designed to withstand, the transmission will last however long the automaker determined is the life of the vehicle. I’m sure this involved lots of life-cycle analysis and looks at warranty data, with the conclusion being: “It’s honestly just better for warranty costs if people just don’t mess with their transmission.”
I’m not saying this is unsound, as I’m sure it’s backed by loads of data. What I am saying is that I hate the whole concept of being unable to drain fluids that are actively suspending more and more wear particles with every mile I drive, and that could become contaminated under certain conditions. Take my 2014 BMW i3. It’s got 143,000 miles, or way, way more miles than any automaker’s differential fluid change interval from just a few years ago. Yes, gear oils have changed, modern machining tolerances have improved, materials have become more advanced, and on and on. But here’s the thing: BMW i3s are failing their rear motor bearings:
I cannot conclude that these failures could have been avoided with clean fluid, but the reality is that fluid cleanliness affects bearing life, and I don’t want my car’s longevity to be limited by by $20 worth of fluids. So I drained my oil and filled it via a 2014-model-year-only fill plug. Here you can see what 10 year, 143,000 mile gear oil looks like as it drains from my rear drive unit:
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As you can see, the fluid looks OK, but it’s not perfect, especially not at the bottom, where sediment has settled:
Luckily, my drain plug is magnetic, so it’s picking up all the metal shavings associated with any geartrain wearing at a normal rate:
Unfortunately, in early 2015, BMW deleted the fill plug from the drive unit. Why? Maybe to avoid incidences of folks filling it with the wrong fluid, but also maybe because it will save them a little bit of money per car. Here’s how much that fill plug costs to manufacture, per automotive benchmarking firm Munro & Associates:
That’s 26 cents per car. BMW made a quarter million i3s, so we’re talking over 60 grand potentially saved (minus costs associated with making the change). But it’s not just the cost of the drain plug that’s being saved, it’s also the cost of the gear box cover, which Munro says costs BMW almost $18 to make; having that threaded hole there definitely adds to that price, so you can expect savings on the cover when that fill plug is gone.
And every penny matters to a “Technical Cost Reduction” engineer whose sole focus is to find ways to pull cost out of the production of a car in a way that — at least in theory — doesn’t negatively affect the customer. I guarantee some genius TCR engineer — whether at the manufacturer or supplier — asked “Isn’t our rear diff filled-for-life? Then why do we need a fill plug?” And before you knew it, the plug was gone.
This leaves 2015+ BMW owners in a lurch, as many want to drain their gearbox oil for peace-of-mind. Listen to what owners of BMW i3s equipped with range extenders have to do to drain their rear diff oil, via :
Apparently, BMW deleted the transaxle’s oil filler plug on BEV models beginning in 05/2015 and on REx models beginning in 04/2015. For models without an oil filler plug, oil must be added through the output shaft hole after removing either output shaft. Not very convenient! To me, this suggests that BMW doesn’t intend on the oil being replaced during the life of an i3.
Yes, they have to remove the halfshaft to add gear oil to their gearbox, and all because BMW removed a fill-plug to save a few cents! How frustrating! Just look at this poor bastard trying to do routine service on a post-2015 i3:
Some folks have found workarounds. Non-range-extender i3s can use their breather as a fill-plug, but with the range extender, that’s impossible to get to, so many folks are — and no I’m not kidding — filling their rear differentials through the drain hole. Just look at this madness:
They rig something up that allows them to seal the drain hole while pumping gear oil in, then they quickly remove their threaded contraption, shove their thumb over the hole as quickly as possible so as not to spill too much gear oil, then remove their thumb and quickly try to thread the drain plug back on. What a nightmare.
I, meanwhile, drained and filled my fluid in five minutes flat, with no mess. All because my i3 hadn’t been out long enough to be TCR’d to death.
Now, it is worth noting that early BMW i3s are the ones most prone to bearing and compressor failure, according to BMW i3 experts, but I bought mine with 135,000 miles on the clock, so I like to think that the design weaknesses would have already reared their heads by now, and that at this point I have a nice, serviceable, relatively cheap, reliable car that that hasn’t been TCR’d to death. In fact, when I was debating trading my car for a 2019-2021 i3, a reader named Nick Nguyen sent me this:
Dude, keep the 2014. Did you notice the pile of cost reductions over the years? For instance, your giga wheels are directional forged wheels, they’re like a throwback to the 90s when Japanese bubble economy cars did separate designs for the left and right of the car. REx models actually have four distinct wheels for each corner due to the staggered setup. Also, the later models lose the handy net under the climate panel and some bungees in the rear. It is very easy to add carplay to an i3- since the display is separate from the brains of the infotainment, everything goes under the rear seat and it just intercepts the knob. Your 2014 also has the widescreen 1280×480 display that is so much nicer
Add to that the fact that I got a brand new battery in this machine, and I really feel like I scored the best of all worlds.
Still, I feel for those poor 2015+ BMW i3 owners.
Cars lasting too long is bad for business.
Ideally the original owner should have a hassle free experience, that includes reduced fluid changes. Just perfect.
Technical cost reduction is not an industry term, just FCA
yep, just fill through the drain hole.
I fill the gear oil in my boats jet drive the same way. Heck, you could probably use the same setup as I do. It’s a cheap hand pump that screws to the top of a quart, a long tube, and a tapered threaded bung that goes in the drain hole (costs $6 I think). You lose a drop or two getting the drain plug back in but it’s gear oil so it’s not running like water. Plus, you should already be set up to catch anything that drips out… because you just drained the whole case through that hole a minute ago.
So now David is finally starting to discover the insanity that German car engineering has become. But it’s timing belts that make a car actually unreliable, right? Transmissions designed to be disposable are annoying, but timing belts make a car truly unreliable /s
I was about to say—aren’t you glad you kept your existing i4?
I noticed something similar on my 2004 Z4. I swapped the diff for a unit from a later car to change the ratio and gone was the drain plug.
Fuck that.
Same goes with BMW transfer boxes and diffs. And if you want your xdrive machine to work past about 150tkm, you really, really want to change the fluids.
I went down the Magna/Kia DynaMax (aka Hyundai H-Trac) AWD system rabbit hole 1.5 years ago and one thing that annoyed me was that while the system worked well, it was filled for life and also directionally sensitive. No fluid spec was provided but some Russians(?) figured it out and rebuilt it – probably the best is the Redline MT-LV with the official fluid being a Shell TF-something. There is a fill plug, but no drain at all. Given it operates hydraulically, I suspect anything but a maximum possible fill would be trouble. But the programming uses AWD all the time and we see a number popping up occasionally with hallmark AWD clutch failure.
I saw an enterprising individual with a Kona drill and tap his own drain port but I have no idea how it went after it was posted.
Wait, if you had to delete one, why delete the fill port? It’s much easier to drain through the fill port than to fill through the drain. Might as well delete both ports and force customers to take the shaft (out).
I used to work for ZF, who I believe was the creator of the “filled for life” transmission. I believe Mercedes Benz was one of the first ones to fall for the “Filled For Life” marketing. Many Mercedes Benz had these transmissions, but they still had a dipstick tube. There was no dipstick, just a locking cap on top of the tube with a tab you had to break off to check the fluid, using a “special tool” Mercedes Benz dipstick.
Anyway… there was a joke with many of the Mercedes Benz and ZF service guys I worked with over the years… “filled for life” seemed to be *reliably* about 125,000 miles…. But many of the customers who insisted on getting a transmission fluid change every 50-60,000 miles, or whatever the previous Mercedes Benz service interval was, ended up having their transmissions last significantly longer.
All the core “filled for life” transmissions ZF received in their shop had the same issue… excessive wear due to dirty oil.
Rather than go “okay, we’re seeing a lot of failures between 100k to 125k miles, maybe we should reconsider ‘filled for life’” they doubled down on it.
As a man who has been on the receiving end of the 5hp30 fluid dumpster fire many times over, can confirm: zf is better at spinny things than slippery things
Shouldn’t be hard to design a drain plug with an integral check valve and cap.
And did you know that you could even add poor man’s autopilot (called Traffic Jam Assist by BMW) to your ’14 for a couple hundred bucks?
https://www.youtube.com/watch?v=X-zD3MtDyd8
I guess there’s your answer for whether or not to buy that i3 Sport you were looking at.
Fill for life transmissions are especially great when they come underfilled from the factory, like every Ford Maverick Ecoboost I’ve seen that had their transmission oil checked, and I’ve seen one underfilled Maverick Hybrid transmission as well.
See, I think this makes the transmission more reliable. A transmission that requires maintenance is unreliable.
A shockingly well-reasoned take from Mr. Timing Chains.
Still nobody had made a convincing argument that a car that blows up every 7 years unless you do invasive surgery is something I should consider reliable. I stand by that piece.
Most vehicles with timing belts have non-interference engines. Losing a timing belt usually does no damage to the drivetrain, and just requires that the engine be retimed.
Generally when the first of your belts dies from natural causes, it’s time to replace all the other belts, including the timing belt (if it wasn’t the first to go).
If you lose your water pump belt it’ll destroy any engine if driven long enough no matter what timing setup you got.
If you lose your fan belt it can lead to overheating which will destroy any engine if driven long enough no matter what timing setup you have.
If you lose your alternator belt you’ll run out of battery eventually, and taking your battery out to charge it before use due to not having a functional alternator is no fun.
So IMHO your critique of timing belts really only works in vehicles that have no other belts than a timing belt.
When my alternator belt went out on my 94 Toyota I thought it would be an easy fix. Nope, gotta remove every belt but the timing belt to get access to the alternator belt, and you gotta remove the top radiator hose at the minimum to be able to do so. When I realized all the belts were the original belts it came with in 94 I just paid a local shop to replace all of the belts including the timing belt. I will say though as I saw how much of a PITA it would be to get access to the alternator belt I wished the Truck didn’t have AC and didn’t have Power Steering so I would have 2 less belts to deal with.
That being said if I had an ICE vehicle that had no belts in it whatsoever and I got to choose what timing setup it had, I’d go with steel timing gears.
I’ll have to call down on the non interference engine thing; we live in a world of 12:1 engine running on 87. That is to say, modern engines are not going to give up that good good valve timing over a potentially broken belt
Yeah I’d put money on the majority of timing belt engines being interference
I’m not saying new cars should have timing belts. I was referring to the article David wrote that OP is referencing.
Most modern cars have EPS, electric fans, etc. in truth they really don’t need belts like older cars did.
You know, I just put a timing belt on my Odyssey last week and it was just enough of a pain in the ass that I may be starting to reconsider my position on the subject.
See, and that’s my point. If you lose a serpentine belt, your car will overheat, the engine will protect itself by derating and going into limp mode, then lighting up the dash-Christmas tree to get you to shut it down. If it’s an older car, you might overheat and pop a head gasket; it’s possible you’ll cause more damage, but not likely. You may lose battery charge due to the alternator not doing its job, but you’ll probably be fine, and the replacement job is usually 10 minutes.
A timing belt in an interference motor is catastrophic and often a major undertaking.
That’s why no interference engine should have a timing belt, those who make interference engines with timing belts got too many screws loose.
Yes, because a plastic guide breaking and causing a chain jam is much better.
Personally I prefer timing gears.
That time my Impreza popped the belt and bent 12 valves was sure fun. Subaru gave the 6 cylinders a chain, but not the 4s.
Our 2012 Forester has a timing chain. I think Foresters have had them since 2009. (If I’m wrong I’m sure I’ll be corrected.)
I still remember my mechanics’ dismay at learning they lost a regular service item.
We could solve the entire problem of timing belts and chains by bringing back sleeve valves! If it is good enough for Avions Voisin, it is good enough for Chevrolet!
Can you drill a hole in the 2015+ models?
With the right bit, you can drill a hole in pretty much anything
An appropriate response for someone with the username Cayde-6
Probably, but then you’ll have to remove and tear the thing down to get the chips out.
I would think that the gear oil flowing out through the hole you’re drilling would do a pretty good job of flushing the chips out. Id use a magnetic drain plug and not worry about it.
Why would the oil flow out of the fill hole?
Even if the fill hole wasn’t going to be in a location where the chips would fall IN and no gear oil would flow out, I’d only MAYBE take that chance if the case were aluminum and the internals were steel and simple, like a differential. A transmission has too many small passages to risk it.
There is a drain hole but no fill hole? Why?
What’s the point of draining the fluid if you can’t replace it?
I had a car that the plug in the oil pan seized and the head rounded off so I pumped the oil out through a tube I stuck in through the dipstick.
I assume it is so that it can be filled during manufacturing
This issue could have been holey avoided.
Reading about this just left me drained.
I’m not filling too well, either.
A lot of cars don’t have fill plugs on transmissions anymore, they instead have a drain plug with a special tool/insert that allows you to fill it from the drain plug. Same goes for differentials, many of which have no drain hole and just a fill hole; you’re expected to vacuum out the old fluid before pumping in new fluid. The joys of working on newer cars…
Differentials lacking a drain plug is nothing new, the standard procedure for draining differentials since the 50s has been popping the cover off.
It’s new to me as a BMW owner, they’ve had separate drain and fill plugs on their diffs since the 70’s.
One neat trick I once saw off-roaders do after a trail-side repair with no fill plug was to put the needed amount of gear oil in a Ziploc bag and stuff it into the housing before putting the cover back on. The gears tear through the plastic once you start driving and the soft plastic doesn’t matter too much.
They’ve been screwing up the drive shafts and final drives off their motorcycles with this since the introduction of the K100 in 1983. ALL wet heads (water-cooled twins 2013-2018, and I think the shift heads, 2019 on, untill they updated the manual I assume for the current ones) get free regular driveshaft inspection with scheduled replacement periodically. Oops, bet they saved a ton of money with that. Love the bikes, but when Germans screw stuff up…
David Tracy you are so naively sweet I wish I could just hug the innocent out of you. Here is the 411. After a car lives out it’s warranty the manufacturer wants it to die. No cost for repair after warranty is over. They don’t want people buying cheap long lasting BMWs. Even EVs they don’t want reusable trade in, resale value. It’s called plan obscelenous. Plan or even program for vehicle to fail or have no parts available. When a BMW owner sells his used car he buys a new one. The same for all car manufacturers. They don’t earn on a resale. They want zero warranty repair then at the end failure zero value. No one gets a deal. Everyone buys news every 4 years, maybe longer with extended loan terms but Noone buys a car without the manufacturer getting coin.
This is one of those things it feels like car news outlets are afraid to say, for some reason. Like it’s a taboo to point out that car companies are deliberately sabotaging their cars to make more money, rather than something we should all be aware of.
Look, Toyota and Honda might be a little culty, but there’s just no denying that they’ve built companies on bucking this trend. Their business model is fundamentally different from the Germans and British and Americans. They make money because their customers drive their cars for 150k, then sell them for great resale value, and then buy another Toyota, and when enough people do that, they don’t need to gouge every penny out of each sale. They make less money on each car, but everyone buys them- Toyota is comfortably the biggest car company in the world by volume. Building cars the right way is *hard*, and nobody else wants to put in the time and effort when they can make lots of money from suckers.
People need to stop buying cars from companies that deliberately want to see those cars fall apart. And outside of Japan, that’s the model everyone follows.
You say that like Honda and Toyota aren’t currently manufacturing “filled for life” transmissions………
> plan obscelenous
*planned obsolescence
I agree to an extent. I was shocked to find out that my BMW/Toyota GR Supra didn’t even have a dipstick to check the oil. It drives me nuts that I have to run my engine for 30 minutes to check the oil. That is ridiculous to me. If the car is low on oil, running it for 30 minutes will crater the engine. How much money would it have cost BMW to put in a dip stick?
But, would I NOT buy the better range i3 that David has been drooling over for months because I couldn’t change the gearbox oil? NO! because all the the other benefits of upgrading outweigh the anti-anxiety benefits of being able to prophylactically change the oil in the gearbox.
I hate that we are being locked out of our vehicles in this way. but its because too many people are either stupid or taking advantage by suing the car companies.
Modern Porsche flat-six here. No dipstick.
I have no issue with the sensors, but I have issue that all you have is the sensor. It’s infuriating. as it just eats time. Now in a busy shop, you can just deal with this by cycling through cars in between other work, but now you’re legit planning around this reality in your every day operations. For a DIYer, you’re just spending way more time.
My engine is IDS, not true dry sump. On dry sump you admittedly have other potential concerns when measuring oil levels, but other manufacturers of high performance dry sump engines still have dipsticks. It just feels like rather than spending the effort on properly solving all the possible packaging and other bugbears to make a dipstick accessible, they just threw up their hands.
I don’t mind the sensors. In fact I think they are cool. I remember in the early 90’s I saw a oil level sensor readout in an Oldsmobile 88 (it might have also shown quality but I don’t remember) and if you can add additional data like that it is a plus. But not having a manual backup in something as critical as engine oil is something I don’t like sacrificing. I don’t say this just for time but for 20 or 30 years down the road when my Supra becomes a barn find and you have no way of telling if there is anything in the engine or in any number of other situations where the electronics aren’t the best way to see what the current status of the oil in the crankcase looks like and you don’t want to dump the whole thing into a pan (dry sump applications not withstanding)
Completely agree I like to actually see the fluid—and smell it.
I have a float and arm like for a gas gauge in the oil pan, the gas gauge does double duty reading oil level when a momentary switch is pressed. However a dipstick is also included and recommended to be used by the OEM.
Is that something you rigged up? I don’t see a way to retrofit a modern engine with that kind of setup. at least from most end users perspective. Besides, you are still not getting to see and smell the oil which is what I am looking for, not to mention that if the electronics are dead you still can’t tell how much oil is in the car.
Ok I’m curious, what car uses a fuel Guage tank float in its oil pan to give an oil level (+ a backup oil stick)?
With no fill plug, is there a breather hole somewhere in the casing? Or is there some sort of bladder in there to deal with thermal expansion, so that seals don’t blow out?
Would there be a thermal expansion issue if you are only filling the oil about two inches above the drain level? It isn’t entirely filled with oil, just the bottom.
Air expands and contracts, too. Perhaps if it’s a shallow enough pool of oil at the bottom, the shafts seals are not entirely submerged, and are also leaky to gas but not oil? Either that or I do think there would have to be a breather hole of some sort.
I’m not that familiar with auto gearboxes. On industrial gearboxes, there’s always a drain hole and plug at the bottom, a fill hole near the top which is generally fitted with a breather plug, and a level hole midway. Either the level hole is fitted with a sight glass plug, or far more commonly you fill the gearbox until oil comes out the level hole, and then you plug it. For boxes designed to operate in multiple orientations, there can be more holes, with their functions swapped according to the installation orientation.
These boxes are often operating in fairly controlled indoor ambient temps all the time, yet still require the breather in order to not blow their shaft seals when the box heats up from normal operation.
I stand corrected. Looked at the (extra) diff cover I have for a future LSD install on my car, and it has a very tiny pinhole in it near the top.
Yes, that’s all it takes. As I understand it, if you are going to be fording water in something that can go deep enough to get near the top of the diff, you either need to run a breather pipe up to over the waterline like a snorkel, or replace your water-fouled diff oil soon after.
Fording water? Not likely in my 1-Series. 😉
My GT6 (and most Spitfires) have a fill plug but no drain plug. You have to suck out the old stuff via fluid extractor and then fill normally. Early Spitties had a drain plug, and it’s not uncommon for people to drill and tap a hole and install a drain in the place where the early ones had it. Is it possible to do that on an i3?
Same with my brother’s ’66 Mustang. Only a fill port.
On the rear axle? You drain them by loosening the diff cover. (Never loved the whole Brown Stinking Niagara Falls situation that follows…) Or are you talking about the transmission?
Ford 8″ and 9″ rear ends don’t have covers in the traditional sense, the back cover is integral with the housing, and the diff assembly comes out as a unit. However, those rear ends are known for practical indestructability unless you mod the car for more HP. You can just tap the housing for a drain plug.
And as the owner of a car with a ford 9″ axle, I should have remembered that… it’s hell getting old. Thanks for the clarification, JumboG!
I don’t know where Munroe gets their pricing, but there is no way they can manufacture that fill plug for $.26.
Doesn’t sound that unreasonable to me considering it’s probably shared with many car models / brands, and is ordered in quantities of 100K+ at a time.
Exactly. It’s the scale of economics.
If their report dates back 8 or 10 years, it’s probably $.46+ in today’s money, if that makes it any more believable.
A quick Google search tells me I can buy an M14 pipe plug for $2, in a quantity of 1. It would not surprise me that I could order them in qty. 10,000 for a quarter a piece.
If you use slave labor in China you could build the whole car for 26 cents.
I know a famous musician that built his own car and it didn’t cost him a dime.
So I looked it up, I have know idea of the accuracy but apparently 30,000 parts is considered the average number for a car. Given a drain plug would be about the cheapest part I can imagine, that pricing seems reasonable for mass produced parts given car prices. I’ve often considered what a car would cost if you were to buy it piece by piece without the economy of scale.
Umm…… Why not? It’s a bolt. Bolts cost like $0.25.
Umm… Magnetic bolts with an internal hex head with a recessed neck for a washer/gasket?