If you want thicker oil and the temperature only dips below 30 degrees F for a few hours a night in the winter, you should consider thicker oil. 20W50 isn’t it. You can use it, but use only three quarts and use straight 30 weight for the other two quarts and you might get less oil consumption. You will notice the difference with 30 weight right away. It won’t pour out like water as does the 10W30. It isn’t treated to just act thicker under certain conditions; it is thicker. See if Jiffy lube has straight 30. They would probably want to sell you some additive at a good markup. Find some other place that will give you the oil you want if Jiffy Lube won’t.