JWalker I was really hesitant about switching over to synthetic oils, even after several of my friends were telling me all the great things about it and how foolish I was for not doing so. I was just having a difficult time believing their tales. (being a certified mechanic I don't subscribe to the "mechanic in a can" theory LOL) Last year the rear end on my truck started leaking so I decided that since I was gonna take off the cover anyhow I would replace it with a larger capacity aluminum finned one. Bear with me... The place I ordered the cover from (Summit Racing) had Lucas Full Synthetic Gear Oil on sale cheaper than the regular gear oil, it even had the correct traction-loc additive in it. Just let me say this... I could instantly tell something had changed. (you know, that seat of the pants feel) So I took the truck out and set the cruise to 60 mph (the speed I usually drive). The "normal" rpm was right on 2000, to my amazement the rpm was now a tick below that. I immediately switched all my oil and lubes to Lucas synthetics, and have had nothing but wonderful results. Mileage has increased Slightly (1.2 mpg average), the engine is not as loud, but the best thing to me is the easier starts. Especially in the winter.
I'm still not a subscriber to the extended oil change intervals, but many are with no problems. I still change mine @ 5000 miles religiously (Oil is cheap insurance as far as I'm concerned) I will say that my friends that go beyond 5000 miles send oil samples to a lab for an analysis. This is just my experience concerning the subject, and I'm certainly not trying to push Lucas oils, I was a true blue "Motorcraft till death" man, but when something works it works. Hope this helps you some my friend.
Safe travels