paul uses oil on the threads so the plug can come out easier (or something like that)
The answer would be look for oil in the intake, top of pistons, combustion chamber, etc. I've always installed my plugs dry. thats just me. Or use antiseize on threads.. When I pull them and see oil I usually find oil other places. PCV is typically one of those area we get a lot of oil in the intake.
Race engines dont use a PCV. For this specific reason. You get oil in the chamber your like fried chicken.. done. As the oil ignites.
When it gets cold outside.. you retune for it. You cannot have a car tweaked out on a summer tune in the cold. Alcohol or not. This is Buick tuning 101. Way before alcohol kits where around everyone would add fuel when it got cold outside by turning down the FP regulator.
Now.. this is important.. if you use the alcohol purely for knock suppression.. meaning you've worked your way up tuning it and using just enough to no let the knock sensor go off.. whatever that is single nozzle, dual nozzle, etc.. and your flowing that amount.. you wont have any issues with distribution. If your trying to pummel the motor with methanol thinking that more is better.. then we have an issue.
Also.. most chips go into closed loop at 140 degree's. If your racing your engine at 140 you still may be in enrichment and the chip will add fuel your not thinking= bad stuff.
Big tractor trailers block off the radiators in the winter to get some temp.. something like this may be good for the Buick Intercooler. But not having temperature data.. all is just a guess. And guessing leaves you with mixed results.
Also remember that evry PSI boost =11df. 20 PSI is still 220 degree's plus ambient coming out of the turbo. So if its 40 outside thats 260 out of the turbo and the IC brings that down to ??? So the cahrge temp will be higher..
My personal thoughts.. way over-alcohol'd motor untuned for conditions in colder weather=kaboom. Cold weather and hurting Buick motors has been going on since 1987.