I'll put in my two cents...
I always said, "If you want to start something, talk about oil."
The oil can't be too good
The filter can't filter too clean
The oil can't be changed too often (if you are looking for engine nirvana)
Most people don't realize that the reason that car companies have made recommendations for extended oil changes is not because the oil is so great or the filtering is so improved, but because of EPA regulations and conservation efforts (different countries, different rules, but tending the same way). Everybody is wanting to be GREEN and throwing away oil after 3,000 miles doesn't fit with making the world a cleaner place.
I guess the difference is whether you are an oil company, trying to sell oil or a tree-hugging Sierra Club member trying to save the whales and sequoias, whether you change oil and filters more frequently or less frequently.
There is a 'best' oil, but a whole lotta 'great' oils. Just pick a good synthetic, because that will protect your turbo much better, especially in stressed situations.
As for filters, I believe there is very little difference between the makes of filters that go into the canisterless 'green' style modern VW diesels. Mann, VW's OEM, Bosch... I wouldn't doubt they don't use the same media. But eventually, they all start to become clogged and inspite of a comment to the contrary, it is not a matter of engine oil starvation, but whether your pressure relief valve opens, allowing infiltered oil to bypass the filter... don't every do that. Don't even risk it.
If you are changing filters every 20,000 miles, you will buy 10 filters over an average life expectancy ownership of 200k, or about $100, give or take.
If you change in 10k it's another $100... or if you figure it out, do you want to spend 1 cent a mile or 2 cents.. or 4 cents?
I put in my two cents.
