I have no doubt that in specific circumstances and conditions, that oil can "last" 20k miles. As you say, companies tend to boast the capabilities of their products. I'm guessing the 20k mile claim is based on the additive package concentration and detergents in the clean oil being reduced/consumed at some average and assumed rate. Its probably a strong oil anyway.

Now that I'm driving more than ever, I, too, am interested in extended OCIs. I used to do 6-7500k miles because my trips and use were of shorter durations. Now that I'm driving an hour to and from work, I've pushed my OCI to 9k miles and looking to try 10k miles. I've had my used oil analyzed every time. 20k mile OCI in an auto diesel of our type is too long but 11k is probably safe.

Fram filters get a bad, often deserved, rap. Their cartridge filters are probably better than their canisters. I get OE filters at my dealer for $8 so that's what I use.

To bring this back, it's not your cat!

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8/2011 X5 xDrive35d Sport, Black Sapphire Metallic, Black Nevada Leather, Fine Burr Walnut Trim
2/2001 M5, Jet Black, Exclusive Complete Black Walk Nappa Point Heritage Leather, Black Cubic Trim