FX 45 oil use

Recently my wfie had her oir changed and they used a blend. I had always used synthetic and never had a problem. I immediately notice sometimes when she started the car ( it has 79000 miles on it ) it would puff out some white smoke. Later the car started clattering and was found to be 4 quarts low on oil. I changed the oil and two months 3000 miles later it did it again. It appears it is not as bad now. There are no leaks. Could the oil service person have disconnected something or could pcv system be causing this. Infinity has no idea:runaround:

My 2004 Murano does the clattering thing. I change my own oil with 5w-30 synthetic and I know I do it right ( light end mechanic for 5 years) Mine will do the same thing and use oil. I'm switching to a little bit thicker oil next oil change and see if that helps.