I'm using high mileage oil because it has slowed the leakage of engine. When I switched from 10W-30 to 5W-30 for the upcoming winter, the leakeage increased noticeably. For future winters would I likely encounter any starting problems with 10W-30 oil at say -10 to -15 F which is usually our coldest winter temps? I have an unheated garage although it's no doubt a few degrees warmer in there.
Before the oil leakage became a problem I was running 5W-30 year round per the manual I know all the cars I had before were fine with a
10W-30 in the winter.TIA Jim