I have 114,000 on my F-150 5.4L. I have been using Amsoil in it since it was new. I had an oil sample done once at the end of the 20,000 miles since the last oil change and there were no problems with the sample. The oil had not broken down at all. I did the oil sample at about 80,000 miles.
I truly believe in their product and run it in all my cars. My 1991 Ford Ranger had Amsoil in it and was changed every 20,000 miles and it ran for 295,000 miles before I finally sold it. It still ran good when it was sold and didn't smoke.

 

Its kinda funny to me, because someone is gonna challenge you or come up with some comment like "I've put xxx amount of miles on my xxx with regular oil. So synthetic oil is a waste of money" I disagree strongly. Anyone who says that has either never used a real synthetic (Personally I don't think Mobil1 or Penzoil count, but lets not go there), or has no understanding of how oil gets destroyed, or how lubrication works.

I would be interested, as would other guys here, of seeing your oil analysis. You don't have to prove anything to me however. I kinda view the oil analysis as a way to see if your situation justifies a synthetic. If the analysis doesn't look right, it means the engine is not in very good condition and either has leaking rings or seals already, or has some other problem.

 

I like synthetic and have used it in all of my cars. My truck gets mobile 1 5w30 with a motorcraft filter. I have 220k miles and still runs strong. I would never compare syntetic to mineral oil as there are some fundamental differances. But "dino-oil" is better than it has ever been and I think that dillegent oil changes is not a bad thing regardless of oil type.

 

I have no problems with synthetics, its the ridiculous miles that people run that make me cringe. But hey if it works. I just wont be doing it.

 

Is there any science behind the statement someone made here a ways back about picking a brand and sticking with it?

I have always used a known name brand and stayed away from "store" brand oils.

I have used Castrol, Valvoline, Havoline, Pennzoil, Quakerstate, Mobil (not Mobil 1), Exxon, and Motorcraft, but I have never stayed exclusively with any one brand. I always used whatever was cheapest and name brand.

In more than close to 800,000 miles on various vehicles, I have had only one failure that I suspected was lubrication related.

At 160K, I tore down my 84 Mustang GT 5.0 and found the rod bearings down to the copper. The motor never actually failed, I just tore it down before it did because it was getting noisy.
I suspect that the wear was lube related because I had been running 10W30 in winter and 20W50 in summer and I had a bad habit of going well into the cold weather in the fall with the 20W50. Sometimes until I had trouble cranking it over in the morning.
I was also using Fram HP1 filters because I got them for free.....
I suspect those filters were too restrictive and were bypassing most of the time.....

All my oil changes were done more or less religiously at 3K unless the manufacturer recommended otherwise. I still cringe a little at the wife's Windstar's 5K interval, but that's what's recommended....

 

I have been told that "Walmarts" supertech, or whatever it's called, is very good oil. I n fact he told me that lots of independent tests concluded the same. I still don't buy it for anything I own, but its said to be good.

 

i use Havoline or Mobil in my trucks. I but the SuperTeck at Wal Mart for the old truck and tractors. There motor oil is made by Exon-Mobil

 

Same. The oils today are 10 times better than the stuff made in the 90's and so on. I have no loyalties to any specific brand...I just purchased 30 qts of Mobil 1000 5W20 because it was about half price. I usually by MC filters exclusively but the price at the dealership was getting kind of steep....I'm trying the Wix filter this time because I heard it performs just as good as the MC.

To answer the question about differences between the 20 and 30 weights, 5W30 will shear down to a 20w when the engine gets hot anyways...during the summer time it really doesn't matter between the 2....winter is a different story. 5W20 is one of the most shear stable oils out there, it really is a no brainer for our engines.