[naz]

guys check out my latest UOA for my sube. the first two samples (right columns) are using shell rotella T 15W40 conventional oil. the third (latest, and left most column) sample is using Castrol Syntec 0W30.. (sometimes called 'German Castrol' or 'GC'.. and supposedly a fantastic example of full synth oil tech.. according to the guys on bobistheoilguy)

some things to note: the GC was used about 1k miles longer than the other two.. the right most sample of rotella T was used during a lapping school.. the middle sample was strictly commuting.. the left most GC sample was used in commuting and in a couple of 15-20min 'mountain sessions'... (not quite full on effort like a track day since it is on public roads.. but certainly lots of full boost/high rpm usage and elevated (~1450F) EGTs (measured in the exhaust manifold near the #3 cyl of a 2.0L turbo subaru)... during the GC sample i am using a mix of 50% 91 octane and 50% 100 octane.. in the previous samples i used 100% 91 octane. (i think this explains the elevated manganese levels.. (blackstone says manganese is a trace element in fuel additives)

another interesting factoid is that GC 0W30 is very sheer resistant.. ie its viscosity is higher than some full synth 5W30 oils that i've seen reports for.

this is exactly what i was expecting.... no difference in engine protection between a good quality dino oil and a good quality full synth oil.... no difference in fuel econ between the full synth 30 weight and the dino 40 weight (avg mpg remains 21-24mpg depending on throttle usage)

the advantages of the GC as i see it are #1 potentially longer change interval and #2 (not really an advantage but more of a physical property) can be used in the winter

i have GC in my car right now, and i will get another sample, but at this point I can't justify the $6/qt for the GC versus the $2.5/qt... i will likely be going back to rotella T 15W40 in the summer since my extra $$ isn't giving me any extra protection anyway

any thoughts guys?