Q: Is it safe to switch from 5/30 weight formula Shell oil to a synthetic oil to store for the winter?

Hi, thanks for writing in. You should not need to change the oil from the 5/30 you have in order to store the car for the winter. I would recommend filling the car up with fuel and having the tire pressures checked and adjusted along with checking all fluid levels. The coolant should be tested to make sure it is good to minus 30 degrees. If it is not, I recommend replacing it or you may risk the chance of the coolant freezing and harming the engine in the process. If in doubt, then have the coolant changed out with new coolant at a 50% coolant to 50% distilled water. If you would like, when winter is over and you are ready to take your car out of storage, consider having an expert technician from YourMechanic come to your garage to perform a tune-up on your car.