2004 Nissan Murano purring loudly

I have a 2004 Nissan Murano. I loved it until it started costing me lots of money, now I’m gun shy. Recently I noticed that the motor is noisy while running and idling both - no difference. I can’t really hear it outside of the car, but I sure can inside. It’s even worse when it’s cold. Is this something to be concerned about?We took it to a local mechanic who could hear the noise, but had no idea what was causing it.

The last time we had several trips to mechanics with no answers, we wound up replacing a transfer case that went kaplooey. We had at least three mechanics on that one. No one knew why it smelled like burned oil, or leaked a little. Until it went out completely. That was painful. About $3,000 later, here we are again.

Any ideas?

@Beeky72 you say can hear the noise inside the car, but not from outside?

Are you talking about a vibration?
If it is a vibration, you might have collapsed motor mounts.