So to preface this I am just going to talk about the importance of using high quality synthetic oil filters with synthetic oil. People will go out and spend $25 or more per 5 qt on good quality synthetic oil. They often forget all of that great oil is useless if it cant be filtered properly.
What is an Oil Filter?
So for those very few that are unfamiliar. An oil filter is a quite simply a filter designed to remove contaminants from engine oil, transmission oil, lubricating oil, hydraulic oil, or any other form of lubricating oil where metal on metal contact is occurring. The specific type I will be discussing today is the Mechanical filter. The mechanical filter is what is most commonly found on most vehicles.
Why do they need to be replaced?
Mechanical by design use an element made of bulk material such as synthetic fibers or pleated Filter paper to trap and sequester contaminants from your oil. As material builds up on or inside the filtration medium, oil flow is progressively restricted. As the oil flow progressively restricts it builds pressure and an bypass valve is opened allowing open, unrestricted and unfiltered oil to get to the engine in time to lubricate essential parts. Thus requiring the periodic replacement of the oil filter in order to maintain functionality and proper filtering.
What are the different types of Mechanical Oil Filters.
Mechanical Oil Filters are separated into two clear distinctions; They are synthetic and non synthetic oil filters.
What is a synthetic oil filter?
A synthetic oil filter is exactly what the name sounds like. It is a type of filter that uses synthetic media. Higher quality oil filters use synthetic media. This media is effective in removing roughly 50% of the particles in sizes ranging from 20 to 40 microns, and up to 24% of particles in the 8 to 10 micron range. These oil filters should be replaced every 7,500 to 15,000 miles.
What is a non-synthetic oil filter?
Typically, disposable oil filters have cellulose filter media. This
media can hold back particles 8 to 10 microns in size and can clean up to 40% of the motor oil. It is advisable to replace them at every 3,000 miles to 5000 miles. These filters are not able to live up to longer oil change intervals and they do not last long enough without breaking down to meet modern specifications.
Why is this important?
Well with the advent of most oil changes getting to or arriving at 10K miles in the US as well as most European manufacturer's OCI's reaching well past that; it is important to consider that even though you're maybe going to get fully synthetic for the life of your vehicle you cannot and I mean absolutely cannon expect a non synthetic filter to take you to that OCI without bypassing or falling apart. Consider this information on all of your vehicles.
A bit of money today is worth much more later down the road when avoiding costly oil and lubrication related failures.
NOT all Synthetic Filters are created equal
Here is the worst part about all of this. Not all of the filters are created equally. Some are constructed with some of the same poor quality parts as standard filters. Some have far less filter media. Some will bypass oil due to flimsy leaf spring bypass mechanisms. Check out the tear downs below to see what I am talking about.
Tear Downs
So these are the two filters are below:
* Both filters are synthetic.
* Both went exactly 10,000 miles in my Ford Focus (This is the only time I took them beyond 7,500 mainly for the purposes of comparison)
* Car Mileage: 298,000 miles
* Mechanical Issues since purchase: None
* Health of Engine: well within tolerance
* Maintenance Habits: Meticulous
The High quality Wix 51348XP
So let us start with the Wix. Its a fantastic synthetic filter according to reviews and marketing. Let's just cut her open shall we.
Using the Dremel tool I sliced it like a hot knife on butter.
So the only place on this filter where steel is used in its construction is the coupling. That being said its not very thick and it does not need to be. The outside skin is aluminum and not very flimsy and feels solid. as you can see there is a metal reinforced silicone anti drain back valve to insure proper functionality throughout the long life of the filter.
As you can see above and below. This is the construction of the bypass is sturdy and done with a spring to maintain the filters functionality. This is pretty essential to make sure the filtering occurs all the way until the filter absolutely is restricted. You will see in the fram that this is not the case with it.
The Media (Below). This filter has a large amount of pleats and contains a thick synthetic fiber glass media which is wire-backed on the other side and has been firmly and solidly pressed on either end to its metal contain. In fact it was so well constructed I could not pull it apart LOL. 
All in all solid filter. I would trust it to go the mileage.
The lower quality Fram "ultra synthetic" XG3614
So it looks nice from the outside. Feels solid and heavy. lets have a looksie
The media. Its terrible. I can push it in. It is not reinforced well. There is a low number of pleats. and I can pull it apart from the body. This is not looking good.
Nice to finally see silicone fram. Wait... Didn't the wix have something to reinforce it. Yes it did. The fram has no such feature and can allow for the mixing of contaminated and filtered oil. This is not something I would be willing to sacrifice my engine to.
The bulk of the weight comes from this heavy duty steel coupling. It has smaller entrances. This can restrict flow which is not a good thing with synthetic oils.
Finally a flimsy leaf spring mechanism for by pass. I simply cannot allow my engine to have this on it for this long of an oil change. It was easy to press in and not nearly up to spec with either American or euro standards.
OCI Madness
So as many people have asked the question: Why are European cars having higher OCI's?
Lets begin with two things that have contributed the most. The oil has come an extremely long way from what it used to be. Gas To Liquid products are proliferating and the base stock is extremely pure and heat resistant. Another contributing factor is engine tolerances and technology. Gone are the days where manufacturers allow oil to sit in places that they would build up sludge. In fact those improvements coupled with tighter tolerances and oil that breaks down far less has allowed OCI's to go further.
So whats the difference between oil in Europe and oil in America? There isn't a difference. The oil is formulated in the exact same way. Volkswagen and Audi specify (as many other Euro Manufacturers including Ford Europe) very high quality, specific synthetic motor oils that have very different characteristics from your average cheap domestic motor oils. Its not to say you don't have the same oils available in America. You do and Despite having strict controls over what can be called ice cream (CFR - Code of Federal Regulations Title 21) the US has no standard for what is actually synthetic motor oil, and has left it to the industry and manufacturers unlike where in Europe its heavily standardized so the companies know what they don't know so to speak. Castrol Edge, as specified by VW Audi, is a fully synthetic oil capable of going 10,000 miles (or 12 Months) in normal conditions. Mobil 1 has both types of oil, follow the vehicle manufacturers recommendations and you will never go wrong in the companies view but if you know you have a synthetic motor oil like Pennzoil Platinum 5w-20 (Fantastic link to this really good oil Click Me! lol) Then you may use 10K service intervals on your American vehicle as well. It will not hurt the vehicle unless your vehicle has been designed poorly like many Chrysler's , dodges, and a lot of GM cars where the oil sits and heat cycles and sludge up in crucial spots. Many manufacturers like Ford, Merc, VAG, and Volvo as well as the Asian slew of manufacturer have designed this out of the vehicle and is not an issue with them. You just need to be informed of the oil your getting. The filter you are getting and the overall design of your engine and its oil passages.
Domestic manufacturers tend to use less expensive oils during their testing. So this leads to the companies not knowing what they don't know and being conservative on the interval to cover all their vehicles securely. Now oil is very thin (5w-20) to help it meet emissions and mileage goals (lighter oil = less internal resistance = less work = less emissions = higher mileage) and can typically be at end of life by 7500 miles. Other things that mess with oil life is how severe of service you have. Many manufacturers specify what these service types are (normal or severe) and alter their recommendations to suit the purpose. This can cause most of the disparity everyone tends to see. Its not that all American vehicles are shit. Its also definitely not true that all European cars are amazing. It comes down to a varying degree of science.
Conclusion
Well guys hope you enjoyed. I will answer any questions and comments if you have them so feel free to ask :)
Though I may refer to @MisteryAngel for some Euro Car information! LOL.
Good Products (as well as product links from here)
Pennzoil Platinum 5w-20 (American and Euro Spec) : AMAZON LINK
Pennzoil Platinum 0w-20 (Asian Spec) : AMAZON LINK
Pennzoil Platinum 5w-40 (For your EURO Big Engine Lovers) : AMAZON LINK
Mobil One Synthetic 5w-20 : AMAZON LINK
Shell Rotella (Best Diesel Oil money can buy); Works on most every diesel asking for 5W-40 CLICK ME
Fram Ultra Guard Filters (Still an okay filter LOL) : AMAZON SEARCH :: FRAM ULTRA GUARD CLICK HERE
Wix XP Heavy Duty Syn Filters: AMAZON SEARCH RESULTS
MANN-FILTERS (Mostly for mercs) : AMAZON SEARCH RESULTS
Use Search results to narrow your findings for your vehicle if you decide to browse
AND BECAUSE I KNOW YOUR CURIOUS
what does the OP Use? With his oil looking so good at that mileage (Hint its not because of the oil or the filter LOL)
Pennzoil Ultra Platinum 5w-20: LINK
(If the price is high on amazon its because it fluctuates between 20 and 43 USD depending on how many are in stock)
If your the kind of person that also desires to run high mileage oil that protects the vehicles seals. Here is another link that maybe useful to you: LINK (5w-30)
