Winter of 2016 my 2009 Escape V6 started a slight knock when cold. I'll take the kicks in the rear for this, but we had a cold spell so I went from factory 5w-30 oil to 0w-20. Noise started after I switched back to 5-30 in spring. This worked on my older vehicles every year with no ill effects. Fast forward to this winter. It knocks quietly when cold only now it doesn't stop. Engine has 114k miles and Ive always used Castrol Edge 5w-30 with oem filter. These escapes are a pain in the winter because the transmission doesn't like to shift when it's cold. This makes it VERY difficult to keep the engine under 2500RPM until it warms up. My wife will let it run until the idle drops down, but she just puts her foot down and doesn't bother with how high it revs. I'm wondering if that accelerated some kind of wear or it was the thinner oil last year, or both. Anyways should I put 5-40 in it or just keep 5-30 in it? I'm putting a can of Restore to seal any wear.