Smoking exhaust - oil too thin?

I'm trying to isolate intermittent smoking and oil burning. I used to religiously use Mobil 1 10W30 Synthetic, but late last year I switched to German-made Casterol 0W30.

I've used GC the last three oil changes, about 4K miles each time. I bought my shortblock used so I'm not sure what sort of rings are used with the Wiseco nitrous pistons. I've always put in six quarts of oil regardless of brand. This last time the oil was at the top of the hash when the oil change was complete.

I have ~500 miles on this oil change and the oil level is at the bottom of the has when cold. Since the reason I bought this used shortblock was a pair of spun bearings, I'm trying to avoid revisiting that point in my life :) The shortblock was originally installed last Easter, but didn't have any smoking until late fall, about the time I switched to Castrol. It originally only smoked under race conditions, but as time has gone by it's begun to do it under idle and/or mostly open-loop conditions.

For peace of mind I'd like to do a compression & leakdown test, but is it possible this oil is too thin and getting past the rings?

I have an oil consumption issue on my 2002 ss. It has 53k on the odometer, and i am going through 1 quart every 1k just like clock work. it is an irritating issue but if i keep adding(maintain level) and use the big oil filter everything is ok, not fatal. i use penzoil synthetic 5w/30(switched from dino oil 1st oil change) and am going to try 10w30 next to see if it slows down a bit. i do not smoke or have any power loss. The newer cars all use oil to a degree i believe. if your smoking your valve stem seals may be failing, how hard do you drive your car? i baby mine since it is my daily driver, but i am also afraid to add power since i think it would accelerate the consumption. I am cosidering german castrol 0w-30 or mobil european car 0w-40, but have read the top end of the motor getting louder after a period of use, and mine is already chattery, and have got piston slap. i still am high on the ls1, but it makes the the lt1 other than it's opticrap look pretty decent to me. i wonder to how those after market pistons are working in the block. my post may not help you much, but please keep posting as i am very curious about what the compression test and leakdown test will reveal, and hopefully others will as well