The Mazda 6 is a 4-cyl (sump 4.? qts - will look up tomorrow in my manual). Zero make-up oil - oil was still at full mark. Dipstick sample (20-30 minutes to acquire - hopefully no dust). Very gently driven about 98% of its miles (wife with kids in tow). Eight mile round trips to elementary school, and lots of 1-4 mile errands & occassional 30-70 mile hiway trips. On a typical day the car doesn't have much time to cool down - homemaker wife has places to go, things to do. To some degree this UOA is moot (the sodium issue nothwithstanding). I've already decided to go to a higher visc oil. As stated in previous posts, this car has a more masculine/quality sound from a visc approaching a w30 than the screaming banshee sound (at slightly sub-WOT and WOT) with the 0w20. I have a hard time believing this Wisk filter (from Amsoil) is getting loaded in 11k. (but ?) Concerning the sodium - after sending the sample off I was chking the coolant level on both of my vechicles (pre-summer travel) - and I noticed the Mazda 6 was well below the "low" level in the reserve tank. I can't say for sure if/when I chked it last (since buying it last summer) - so I'm not sure what's up. But will monitor closely starting now. TBN at 1.6 at 11k. I didn't expect this result. Could the "elevated" sodium be affecting this? Meanwhile, since I'm departing from the xxw20 class, all xxw30 options are now on the table. I called my local Schaeffer rep last week (before the UOA results came in - I was also in the process of acquiring some Neutra 131 for my Sienna) - described my Mazda app to him (1 yr OCI/~12k miles) - asked him if 9000 5w30 would handle this (btw, he's old and wise in the ways of lubricity - operates a fairly significant oil distribution ctr - full warehouse operation). He stated that, indeed 7000 5w30 would be fully up to the task - he stated that his OCI is 1 year and about he same miles as mine - and 7000 5w30 has proven itself for him - "good TBN retention" etc. (In the past he has also pushed (marketed) 7000 instead of 9000 - except in "extreme cold apps"). While taking dipstick sample, I drained a full qt and replaced with Mobil 5000 10w40. I was wanting to test difference in acoustics with the increased visc. Very pleased with the results as stated above. I'm comfortable leaving this present fill in (given the refresh with the 5000) till I can find time for OC (and decide on next oil). Thanks for any input!