So since gas prices have gone up, I have been putting the cheaper gas in my 2018 XC60. I spoke to Volvo and they said that is probably what the problem is since my check engine light is not coming on. It’s like a rumbling noise that increases and decreases in loudness. Problem is they can’t get me until the 30th and today is only the ninth. Has anyone experienced this and is it OK to drive it In the meantime?

 

Put the correct gas in and see what happens. Go with the highest Octane available to fill your tank to hopefully correct the lower octane gas already in the tank. It is perfectly fine to mix them.

Octane rating on gas is to prevent pre-ignition (cylinder firing before it is supposed to.)
Video below on a sample of noise and useful info in the comments too.

 

Thank you so much for taking the time to reply. Turns out I hit a pothole so hard the other day that the black plastic that goes underneath the engine block on the bottom of the car got hit pulled back so when I was reaching higher speeds, it was literally flapping in the wind. Although this experience did scare me back into making sure I put the correct gas in my car because I thought that’s what the issue was.. thank you!!