When i first got my VX the PO said he ran synthetic oil. I ran castrol 5w 30 synthetic. I went through around 2 1/2 quarts in 3,000 miles. I did not change the pvc valve. The last oil change I changed the pvc valve, switched to Valvoline 10w 40 High Mileage non synthetic oil. I have around 1500 miles on it and only used about a 1/2 quart. Not sure if it is the new pvc valve, (old one did rattle like it was not plugged up) or if it is the thicker oil, or if it is because of the high mileage non syn. oil, or the additives int the high mileage blend?
My VX has 120,000 miles on it and has the original engine as far as I know.
I have no problems with it starting parked outside in single digit weather with the thicker oil.