Try this. Jack up the front end of your car top it off with fluid turn on your heat and let it run with the cars front end up high. Start this when the car is cold so you can remove your cap and top it off as it warms up.
What concerns me is the white smoke you keep talking about. My mind tells me the shop got an air pocket in the system and overheated your car blowing a head gasket.
But I always think the worst things... Check your engine oil to see what color it is though.
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Forged bottom end. AGP TT, Dual nozzle meth, ID850's, Livernois dual fuel pumps, ECS BAP, 25% UDP, 3 inch Magnaflow catback with X pipe, Mantic 9000 clutch, DSS 1000hp axles, DSS aluminum driveshaft, ZL1 rear end, solid subframe bushings, HE differential offset bushings, BMR Trailing arm, BMR toe rods, Lingenfelter LNC-2000,SJM Line Lock, and much more Built by, FSP, myself, and some a few others, Tuned by FSP and me 800ish whp