Interesting read. I always thought you needed to run at least two to three runs of the same oil/grade, in a mechanically sound engine then make the switch and repeat before coming to any conclusions. The problem is it would take a very long time for most of us to complete the testing. I'm with Shannow on this as well.
You've run UOA on a 30+ year old engine with mechanical problems and 260,000 miles on it?
There are so many uncontrolled variables here that your UOA don't demonstrate anything. Certainly, a few PPM on one metal in this older, failing engine are not the "final verdict".
Did you not note my End Of Discussion post...hmmmm???
The copper levels in those UOAs look horrifying to me, particularly with the M1 when the engine is new. I know some engines will read high copper when new, but they still look nuts with Amsoil when the engine has over 30kmiles on it. Was that just the nature of that engine, maybe due to an oil cooler or something like that?
Interesting that they found that Amsoil thickened so much...M1 has the (deserved?) reputation for shearing, and it seemed that even the promotional materials for M1 AP showed it losing viscosity faster than the oils to which it was being compared. But, XOM claimed that the catastrophic thickening would occur much later with the AP, hence the 1 year/20kmile claims.
Oil consumption with TGMO 0W-20 SN was small thanks to new valve-stem oil seals -- about 0.3 quarts in 5,000 miles. The last fill was Mobil 1 (M1) 0W-40 SN (older, non-FS formula). Oil consumption stayed the same or perhaps increased slightly to about 0.4 quarts in 5,000 miles. I was surprised that thicker oil didn't improve the consumption -- in fact made it slightly worse.
Did you replace PCV valve and piston ring when valve-stem oil seals replaced ?
I used M1 5-20 in an engine calling for 10-40 in 1978. Engine started much better in cold temps and ran smoother as well in all temps.
AND we've been over (and over) that the M1 5W20 was VII free, all basestock, and was more like Redline 5W20 n reality, with it's 2.9HTHS (which some would call "really a 30, including Dr Haas and CATERHAM, in spite of what J300 states)...and that was in an Era when 10W40 had no HTHS minimum, and may of them were woefuly inadequate....which lead to some OEMs decrying 10W40, and denying warranty should such oil be used.
Industry then started investigating "apparent" viscosity in high shear, and assigned 0W, 5W, and 10W 40s the same HTHS minimum of 2.9 as they assigned the 30s...that's how "good" the 10W40s were back then.
And so, when Mobil stated that their 5W20 monograde (no VIIs) gave the same protection as a 10W40, they weren't telling fibs...but they aren't (and we've been over this more than a dozen times) the same measures...and TGMO has nearly nothing to do with M1 5W20 the way it was originally made, in any way that you cut it....
Interesting results, and I agree more testing is needed. I am currently performing a thick vs thin test of my own; it will be awhile before it is finished but I'll try to remember to post here when I have the results.
Tig has about 3 posts over and over again don't even bother.
Gokhan, great information and very interesting post. Thank you for taking the time to do so. I personally don't think you have the data to make the conclusions you did, but I am not going to sit here and throw internet rocks either.
It would have been nice to have seen the exact same oil brand and formulations compared against each other except in different weights.