Sure Otto, synthetics are made by nature to have a longer useable life than petroleum based oils. However THERE ARE specific synthetics with additive packages designed to last longer than an average 100% synthetic. Obviously my diesel oil reference was hard for you to digest, it was simply an example to illustrate the point that there are two oils designed for a similar purpose(e.g. diesels) and one is a standard service synthetic, and one is an extended drain synthetic. Extended drain interval synthetic oils are in fact a reality...A person saying that they're not is either someone who is ignorant about the current oil industry, or someone who simply doesn't believe in the merit of extended drain interval oils.
"Because of the robust polyester base stock and high-performance anticorrosive additive package in Red Line oils, they are ideal for use in street-driven vehicles at extended drain intervals"(redline oil's website)

 

badprarie,
i'm not real hip on the fram filters, In preference from most expensive to least expensive probally is this:
mobile 1 or amsoil (lots better filter medium, not just paper)
wix or napa gold, or carquest (in the gold line about twice the paper filtration)
purolator

as far as oils, well I'm pretty cheap, but I have had good sucess with mobile 1 15-50 in my streetbikes, and I run it in the prarie as well,
I really don't buy into all the "atv oil" or "v twin oil" or "motorcycle specific" oils, for this one reason..
on my 15K streetbike I run mobile 1 15-50 red cap auto oil, about 4.25 qt, (yamalube is 4.0 qt) this is (or was the last time I changed it) a auto oil that is sf/cj without all the friction modifiers that would cause clutch slip since that time I guess they have changed the additives to it and came out with the "v twin" oil, still just like the old tri syn red cap 15 50, except it is over 7 a qt.. is it really 3 bux a qt better, not in my mind..
now on the extended drain interval.. personally I don't exceed 4K or so on my street bike, but that is me, specs call it to be changed at 6K miles with yamalube, but bear in mind that bikes are lots harder on oils than cars are, reason being the shearing action of the wet clutch & transmission..it loses some of the viscosity fairly quick after 1500 miles, no matter what brand you have in there..

on the prarie, since I don't go in the swamps, mostly hard pack, I haven't given it a lot of thought, it seems like contamination would be a larger problem than the oil breaking down..I have 300 miles on it, & have no reason to change the oil as of now (I changed to mobile 1 at 75 miles or so) I could probally double the milage of specs, but remember the contamination factor..as long as that is not breached, the oil won't break down.

yes, the 100% synth oils are good, they do what they are supposed to, but is 1 any better than the other? is 1 3$ a qt better than the other? common sense should be your guide. use the oil that meets the api specs, that you feel comfortable with, and change it according to specs, more or less, it makes no diffrence if it is crisco, olive oil, canola oil, dino oil, or synth, AS LONG as it MEETS the SPECS..and you are comfortable with it..

in the streetbike world, some folks use the 4$ qt synth oils or more, run them same milage, some longer, and some use fleet oils about 1$ qt, (rotella, delo) as these have higher phosphorus content, and change them sooner, who is right?..I'd say both of them..what ever feels more comfortable to you, that is what you need to do.

 

Just to further back up my point about extended drains with high quality group 4 synthetics, here is a reply from a lubrication engineer friend of mine I got today in regards to this topic...

"The extended drain capability of various formulations is determined by the quality of the basestock blend, plus the quality/quantity of the additive chemistry (including the VI modifier). Certainly, a top tier, 11-13 TBN, PAO/Ester formulation like the Mobil 1, 0w-40 is going to be capable of long change intervals. However, most OTC synthetics are Group III based and have TBN's in the 7-9 range. For example, the most recent data I've seen on the 10w-40 Syntec showed a TBN of 8.75. This latter class of lubes might last 50% longer than a 5-7 TBN dino oil, but not nearly as long as a 12 TBN, PAO/Ester formulation like Delvac 1.

In other words, there is quite a bit of variation in the quality of the sylubes out there, based on the market they're intended for and the price point at which they sell."