My experience's have led me to a conclusion similar to RH77. It didn't seem to me like the synthetic's did anything much, except cost significantly more.
Their is a full synthetic, which I think MetroMPG is using. It's rated to go 100,000 miles, which is good, but you still have to change the filter's and replace any lost lubricant, to a point where it just becomes pretty pricey, from a cash standpoint. It seemed to me that unless you had a new car, which did not use any oil and you were 100% certain you were going to drive it at least the 100,000 miles, that it just wasn't really worth the cost.
For me, I have been using generic Pep Boy's oil, 10-30 in the winter, 20-50 in the summer and all of the engine's I've torn down, I have been able to do a economy rebuild, where I just replace rings, rod bearings, main bearings, oil pump, water pump, gaskets and so forth, and although their has been some wear, it has been minimal enough, to work fine. I have a couple of cars that the motors have over 200,000 miles on and they basically don't use any appreciable amount of oil.
Consequently, my choice has been to just use regular oil, change it when it get's to dirty and I get around to it, get rid of all of any gunk, or whatever and leave it at that. As far as fuel saving's, I can't see that their was a appreciable enough different to really justify the additional expense.
Thanks for the link on that PCV catch device rh ! That's something I'm interested in . Maybe I'll start a thread to see how many people are doing this and their results .
Concerning the dino vs. synth issue - if it helps out on cold startups and reduces friction overall , even if it doesn't make up for itself in FE , I think it's worth it . I also own a Chevy truck with an LS1 aluminum block V8 transplanted , that has always had Mobil 1 in it . When I do use the truck it's very rarely for a 5 or 10 minute trip - it always warms up and stays warm for a while . I change the oil twice a year in it or about every 7-8000 miles . Once I change it , the oil always stays really clean , transparent and gold looking for at least 2000 miles , and then it slowly changes darker and less transparent , so I think the engine is clean inside and that this OCI is ok for this engine . And for a full size truck , I think 21/22 mpg is pretty fair . I estimate I'm spending about $60 / yr in oil changes. I use either Wix or Delco filters at about $6 a piece. Does this sound like too much annually ? THANKS! Jim