When Do Frequent Maintenance Intervals Make A Car Unreliable?

So I am the first to admit that I am an abuser of car. I select them based on their ability to put up with abuse.

A friend once remarked that an air cooled two stroke is the perfect motor for me. No oil changes needed and no cooling system to maintian.

For a car if you have to crack open the motor for anything sooner than 150K I deem them unreliable.

I was recently stunned to learn of the changing the rod bearings in a BMW before 100K was a thing. While it was pointed out that you can drop the pan in the car I still would this a flawed car / unreliable. There are plenty of other examples like having to change cam belts at 30K. 

So where is the dividing line for the hive?

For me it's more about predictability. If I know when things need to be done, I'm happy to do them. 
 

But if it breaks unexpectedly and leaves me on the side of the road, I'm done. 

IIRC Ducati expected you to bring one of their machines in for a major service every 5000km or so.

It depends on how complicated the maintainance is, like a timing chain that doesn't last well over 250k with no attention is ridiculous, or wet timing belts that last 100k.  The biggest one for me though would be when original quality parts are no longer available and you have to use a poor quality replacement that doesn't last near as long.  At that point I'm ready to get a different car.

I think you have to contextualize the severity of maintenance with what the engine is capable of to determine if it should be called "unreliable" or "flawed".

The BMW engine that has the rod bearing issues - the S54 - is an 8,000 RPM screamer that makes 107 HP/liter without forced induction. That's gonna put some stress on the rotating assembly and I don't see such an engine needing bearings at 100k as flawed or unreliable. Exotics like Ferraris need similar maintenance and it's just part of the process, when you want exotic performance and crazy power for a given displacement it's gonna be hard on stuff.

Now, the Land Rovers that used to drop cylinder sleeves into the block for no good reason, or the Audis with the self-destructing timing gear that let go before the first inspection interval...that's a flawed/unreliable engine.

I don't know but, I do know that I'm very unhappy that I'm going to have to do a head gasket on on my truck at just 125k miles.

If I have to enter the engine's internals before 200k, it's not up to par with most modern vehicles.

Tom1200 said:

So I am the first to admit that I am an abuser of car. I select them based on their ability to put up with abuse.

You may want to look at modifying your driving habits - driving a car hard isn't necessarily the same as abusing it.  A little mechanical sympathy will go a long way in extending the car's service life.

In reply to pointofdeparture :

But to that point so is my Mitsu. It's a 8500 RPM screamer putting out 106 HP per liter and there is no required bearing replacement in it. I've seen more than a few over 100K miles and never cracked open. 

There are ways to make things reliable and long lasting. 

it's lines of thinking like this that got us transmissions with "lifetime fill" and no dipsticks to check. How soon will they be clamoring for engines that never need an oil change?

I think it's the old school way of you had xyz due at 15k miles, then at 30k, then 45k, but then at 50k was a whole different list of things then 60.... so what happened, everyone ignored it. So everything got better and largely because if it beeps at you fix it. Doesn't fix the need for shocks and or struts at 60k.....

I mean NASCAR can run 78-8400 for 4+ hrs pretty much continuously. They idle at 2-2500... Hell they ran it at LeMans with a similar spec engine. The pistons actually kiss the cylinder head every revolution. How many engine failures do you see? A handful maybe per year instead of half the field for one race. Now they are getting upto 3 races per engine.

In reply to ShawnG :

Valve service intervals on Ducatis have grown, but in the past some have required a lot of maintenance; my old MS4R, for instance, required valve clearance checks every 7,500 miles and cam belts every 15 or so. 

I'm wondering if the Waddington Effect (during WWII, Waddington found that preventative or scheduled maintenance actually increased breakdowns of aircraft) is applicable to this thread.

https://resources.savvyaviation.com/wp-content/uploads/articles_eaa/EAA_2011-03_the-waddington-effect.pdf

Frequent service intervals do not make a car unreliable, because you know they're coming and you can rely on them. They might make it more work to own, but that's not the same as unreliable. Unreliable is unplanned/unexpected failures. 

Now, you can make a reliable vehicle unreliable by skipping those maintenance intervals. But that's a choice.

I thought this was going to be about the Waddington effect as well, but the first post is mostly complaining about having to take care of your stuff :)

In reply to stuart in mn :

I am lazy about maintenance. The halfshafts on my Outback have had ripped boots for the last 10K.

ShawnG said:

IIRC Ducati expected you to bring one of their machines in for a major service every 5000km or so.

Even the Desmo RR did not have service intervals that short. Even my V4SP is every 15K miles now for valves and I am going to be honest even that is overkill. Don't get me wrong they are expensive and time consuming to do ~16 hour of book time for the V4 for the first major but you know that buying the bike. 

I would rather know up front and expect the price and understand why I need to do it over buying something with say a fully sealed transmission that you cannot buy even seals for and they just expect you to replace them. Looking at you Nissan and a few others. 

In reply to Keith Tanner :

You can look at that argument another way- car A requires work every X,y, and z miles or it will break down. Car b requires less work every y miles. Most people will agree that the car that needs less work is more reliable. 

In reply to pointofdeparture :

My Datsun puts out 100bhp per liter and turns 8200 rpm........rod bearings go forever.

Honda motors do the same.

Purely personal but I don't find that service interval acceptable.

For me noting the performance is an excuse a lot of performance cars use.

alfadriver said:

In reply to Keith Tanner :

You can look at that argument another way- car A requires work every X,y, and z miles or it will break down. Car b requires less work every y miles. Most people will agree that the car that needs less work is more reliable. 

They are using the term "reliable" incorrectly then. Lower maintenance, sure. Not less reliable unless car A also has unexpected failures when properly maintained.

Unless these are also the sort of people who use "literally" in exactly the wrong way :)

I don't mind too much as long as the manufacturer didn't do something stupid like put the belts on the back at the firewall. Seriously BMW and Audi? An engine out for what should be a simple job?

In reply to Keith Tanner :

I know what your position is, but what is the difference between lots of scheduled required work and a little unscheduled work?  $5000 of required head work every 50k miles to keep a car running is generally worse than a surprise $5000 bill once over 150k miles. 

In reply to Keith Tanner :

I am not complaining about taking care of my stuff.....I'd actually have to take care of them for that.

I buy cars that only need oil changes and air filters with first major service no less than 100K. 

Also note I am marginal mechanic so the less I touch them the better.

mad_machine said:

it's lines of thinking like this that got us transmissions with "lifetime fill" and no dipsticks to check. How soon will they be clamoring for engines that never need an oil change?

My lawnmower (2 yo) already has no oil change interval required, just top off .😬

In reply to alfadriver :

I think that depends on if that surprise left you stranded. If you buy a car knowing that maintenance is going to be expensive, that doesn't make it unreliable. A surprise repair, by definition, suggests unreliability.
 

from Cambridge:

Reliable: Someone or something that is reliable can be trusted or believed because he, she, or it works or behaves well in the way you expect.

In reply to No Time :

My mower is 17 years old...........I've never changed the oil. If belches smoke on the first start up if the year, I top the oil up now and again.