Mr.T

Aluminum (AL) 4 ppm
Iron (FE) 9 ppm
Copper (CU) 17 ppm
Lead (PB) 0 ppm
Tin (SN) 0 ppm
Chromium (CR) 0 ppm
Nickel 0 ppm
Cadmium 0 ppm
Silver 0 ppm
Vanadium 0 ppm
Silicon 9 ppm
Sodium 9 ppm
Water <0.1%
Soot <0.1%
Viscosity @ 100C 13.7 cSt [new oil reference, 13.7 cSt]
TBN 4.7 [new oil reference 8.0]

3300 mile UOA (used oil analysis) using 5w-40 (Amsoil AFL). The oil and filter are still in service, still plenty of life remaining. It's not a daily driver, the tested period included a wide range of driving -- From 4-Lo desert trails at 110 degrees, highway and city driving, and some snow this winter.

Comparing other 3.8 JK oil analysis I've found on the net, this is one of the best I've seen. It's noticeably quieter than 5w-20, and seems to run smoother -- both lugging at low RPM on a trail, and shifting quickly at 5000 RPM on a freeway on-ramp. No detectable reduction in MPG compared with 5W-20.

Bottom line is that this oil analysis with 5W-40 shows low wear, and that confirms a subjective opinion based on how it runs, sounds, as well as how clean the oil looks. Subjective opinions and arm-chair theories are not that reliable, but it's hard to argue with the numbers.

Edit: I've used Blackstone, but not for this particular analysis. One of the niceties of Blackstone is the "universal averages" for comparison in their reports. Below are some recent 3.8L averages for wear metals, similar can be found in this forum and others.
Al 4
Cr 1
Fe 17
Cu 21
Pb 1

ronjenx

Keep posting subsequent oil analysis results. That's where the story is told.

jeeper32

I know there have been some tests done on 10w-30 and like also. I've been using it and prefer it over the 5w-20 but i dont have any test analysis results to share.

zstairlessone

Did they check TAN,TBN and viscosity? The first two will tell you your RUL (remaining useful life) the third will be checked at 40°C or 100°C and will tell you if contaminants (like soot) are affecting the oils ability to do its job. You can also do a business card dispersant test to see if your oil has reached its end of life. These all tell something different about the oils condition and whether it should be changed.

zstairlessone

Edit: if the filter is doing its job don't extend the change interval for it (don't stretch it out) as it will bypass when differential pressure across the media becomes too great effectively removing the filter from the system - not a good thing, in case you are wondering

BacasJK

Ha!!! I can totally agree! I've been using the 0w-40 Mobil 1 in both of our Jk Rubicons 5,000 miles. Now at 17,000 miles on my JK and 15,000 on the wife's, they run quieter, smoother and no oil burning. I was laughed at on other Jeep forums and nobody believed me. IMO, these Mopar engines love the thicker oil at operating temp. Period.

To each his own.

Martin
Mine-2011 blk. Rubicon.
Hers-2011 slvr. Rubicon.

blw

I'm in Oregon, but near Portland, so I don't get the weather extremes you may get if you are on the Eastern half of the state. I moved to 5w-30 synthetic: are you using 5w-40 because of the extreme temp differences where you live, or just to have a thicker oil...

Mr.T

TBN and viscosity @ 100 C added to first post, didn't pay the extra for TAN & viscosity @ 40 C.

The old Business card / white paper test -- I can tell you're old school too Oil analysis is expensive, but I've done it occasionally for many years. To me, it doesn't make economic sense to do it very often. I mostly justify it as insurance against a hidden failure that would really ruin the day (and night, or longer).

Speaking of insurance bets, that's mostly how I see 5w-20 vs synthetic 5W-40. 5w-20 is fine 99.x% of the time, but Murphy and his laws eventually show up. Something like a hot day, the electric fan quits or a coolant hose springs a leak, and the engine gets hot but you can't pull over in traffic going 75 MPH. It's these rare events that ruin most engines, not normal wear.

Mr.T

Yes, to each his own. Also, the wear metals were about 50% less with 5w-40 sample. Two samples don't prove anything, there's too many other variables, but I'd bet on less wear metals if I had too.

El Dorado

A single oil analysis is only good for a baseline and some even believe the first two are a baseline. In order to get the most amount of info, you need to keep testing at regular intervals to see the wear trends. Another very good thing to do is cut open your old oil filter and pour the contents into a paper coffee filter. Try to wash the filter element with a bit of solvent to get everything out and into the filter. If no metal in there it is OK, but any and I do mean any metal in that filter is bad news. The very first oil change will probably show a small amount of metal but that is normal. From there on out, no metal. What I have described it pretty must standard in the aircraft industry. That trend info can predict many things to include the expected lifetime of the engine or upcoming catastrophic failure..........