That is extreme usage...
The operating informant should be added to common sense when considering the cabin filter.
IMHO based on servicing years of cabin filters they should be changed at least every seasonal change and more frequent in operating area's that dust, fire smoke and other air born contamination can affect their service life.
I might add that when you set the HVAC system cabin filter filters both recirculated air and also ram air. So if you like breathing you old air and anyone you have had in the car plus all kinds of other air born bacteria that does not filter out very well in most all cabin filters.... make sure your Health insurance premium is paid up. LOL

As for going 75k mils on spark plug it simp... they may fire but nowhere close to efficiently igniting the AFR as they did when new or even at miles beyond 10k. 15k max if you are desperate for money to buy new ones. LOL Testing by way of oscilloscope have verified this for decades. Spark plugs are the least expensive and often DIY friendly part to change that has more direct effect on MPG as well engine performance than any other serviceable engine part. Don't believe the spark plug ads but do read the "up to" often in them. Also DIY often claim ridicules miles without ever having an issue but them if you follow them when they do change them write about how well their engine now runs and picked up power lost, and MPG is returned. Go figure. LOL

How do I know this ...
Sold and or used likely 10 thousand or more spark plugs so far in my life. LOL

 

Am I understanding you correctly, suggesting spark plugs should be changed every 10-15k? If so, you are the only person I have ever heard this from. I change my cabin filter yearly, as it only costs about $10, and the process is so easy. Spark plugs are a bit more involved, so I am doing it at the recommended 40k interval.

 

As i said the scope does not lie.
Any person can go to a shop with an oscilloscope and run a baseline, then change ONLY ONE SPARK PLUG with a new one and do another run. You will be able to see the spark energy and even if you don't
understand the data on an oscilloscope scope would be able to pick out which cylinder had the new spark plug. The more spark energy the better and more complete the fuel witl ignite and burn the fuel.
As for you state I am the only one that is incorrect you are just asking the wrong people and reading the wrong information and or just not on the best forum for these kinds of Q&A because average owners would rather follow the crowd then the facts like you dont want to think they need .
I would also mention that most drive and race their vehicle's when they arrive at the track one of the things done is to change out the sparkplugs. Wonder why??? rolmao!

Going 40k miles will diminish the performance of spark plug energy output by 35% or more (depending on the rest of the condition of the engine and ignition supportive parts) increased fuel consumption and generally a slowly degrading of normal power output. FACT!!.
Your spark energy is from idle to max out at about 3500(under perfect conditions) because the coils used are not variable magnetic. So spark plug health is the upmost thought when considering getting the best performance from your engine.

So once again the most inexpensive and generally the easiest part to change that WILL make the biggest dereference in performance engine output and improve MPG is more frequently changing spark plugs.

Why do some religiously change their engine oil and filter and many before the service recommendation but disregard spark plugs?


As for cabin filters it your life and your health.....

 

It all depends on your vehicle engine, driving habits, fuel quality and what type of plugs you are using.
General science-based recommendation for passenger vehicles is copper 30,000 - 40,000 miles, platinum 60,000 - 100,000 miles and iridium 100,000 miles.
As with almost every manufactured item they can be faulty when new, fail at any time and start degrading the minute you start using them.
The only way to know is to have the equipment to monitor the performance on a daily basis which the average driver doesn't have or do.
And the main reason for replacement timing, unless the item has failed, comes down to money and how deep your pockets or bank accounts are.

Most people replace the typical refrigerator every 10-15 years, but they never do any maintenance or check the charge, and it is a certainty the peak performance is gone long before the 10-year mark.
And this is an item that runs 24/7 much like well pumps, freezers, sump pumps...you get the idea.

 

Any person can go to a shop with an oscilloscope and run a baseline, then change ONLY ONE SPARK PLUG with a new one and do another run. You will be able to see the spark energy and even if you don't

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
It so hard to post experienced and fact-based information based on real world testing on forums. To much finding what you want to be the answer on the internet.

 

Actually they do...(at least those that participate of forums like this) and so many on this forum alone have them ... cheap Bluetooth scanning tools.

In the end as always on forums like this its your vehicle your money and it's also your problem when things happen you could have had control to prevent if you only trusted what some members post?

 

This is what confuses many (including me!). The 2.5T's plugs are iridium from the factory, yet the change interval is 40k.

 

The main reason for those spark plugs is the TURBO charger when booted can increase the EGT and combustion temperatures which play a direct effect of the life stan of a spark plug.
So, its easier to use a spark plug that will last longer overall usage when using a boosted engine. Heaven forbids suggesting that sparkplugs need to be changed more often the basic internet information or even from the auto manufacture. Buty hey they also print that automatic transmission is lifetime no service as well. LOL
There is more technical information but that is the short version for best understanding of most reading this.

And I will repeat again that using diagnostic equipment and DATA logging ignition and fuel injection activity can easily make believer about what I have been saying. LOL

This is that same sort of responses when I try to suggest that most are doing it incorrectly when reading the spark plugs using those charts dating back from the 1950"s even if they have a ilustrated date in the 20"s (2010-2015-2022 etc.)

From my earlier response:
As I said the scope does not lie.
Any person can go to a shop with an oscilloscope and run a baseline, then change ONLY ONE SPARK PLUG with a new one and do another run. You will be able to see the spark energy and even if you don't
understand the data on an oscilloscope scope would be able to pick out which cylinder had the new spark plug

 

Hahahahahahaha...good one.
There are 242,293,001 current drivers just in the USA.
How many of them are on this forum, or any vehicle forum, and how many could even explain what Bluetooth is let alone use a scanning app, including some on this forum?
Doing service for as long as you have you must know the average driver has no idea how any engine even works let alone anything about maintaining the parts involved.
The majority of US drivers (and most every other country) have zero mechanical aptitude or abilities and have no pretense of learning any.

The average person should get a physical every year but just like the average vehicle driver, most never do until something goes wrong.
As a species, we collectively aren't all that bright and anyone (like me and yourself) that has worked in any service to the public, can attest to that

 

agreed...people are capable of learning to maintain a vehicle but it depends what makes the most sense to the individual...i would say people fall into a few categories....1) if you have the time, money, capability and drive to learn, 2) lack of money and it's necessary to learn, 3) you have money but no time and just pay someone to take care of it and worry about other things in life instead of adding another job description to your resume and 4) a little of all those approaches, fix/maintain what you have the tools for and are capable of yourself and let a shop/dealer handle the rest...another thing that is currently helping people diagnose, fix and maintain their vehicles while saving money without necessarily having to retain information or read up prior to maintaining/fixing is AI and it will keep getting better