My singer built in the 1950's ... I oil about every two weeks. My newer Viking.... I can't oil.

My mechanical machines I keep doused in clear new machine oil. I have a Brother 1500 and oil it every few hours of sewing.

Each machine is different. I have a BabyLock & an Elna. Neither gets oiled until they are serviced. That's what the tech told me.

I have 3 different brands of machines, all 3 have different oiling requirements. I oil them as often as their manual says to.

It depends on the machine!!

My Huskvarna ... NEVER.
My Janome ... I put one drop of oil in the wick under the bobbin, one drop on the needle bar, and one drop on the edge of the bobbin race - every time I clean the bobbin area, which is about every two bobbins.
My vintage Singer machines ... I don't use them very often, so I oil them with each use.

My sewing and sergers are all electronic so self oiling................at least I hope they are. My quilt machine after every bobbin change and then after I'm done with a quilt, I clean and oil it as it may sit for a day or even a week/month.

I have been told that if a machine that needs oil sets long times, it should be oiled before use as the oil runs down and leaves dry spots.

I try to follow the direction in manuals or when I forget, I oil when the machine sounds a bit loud.

Follow the manual. I have older machines that I oil as suggested in the manual. I also have three new machines and they do not need oil at all. And I never use can air on the enclosed machines. Big no no. I do have a long arm, APQS and it gets oiled every other quilt. I do put oil on it when I do not use it for longer than a week. Then I clean in completely before using it. Good luck

I oil any of mine when the mood strikes; but don't use that as a guide you should follow. DH and DS can both service machines, so I let them have that little worry--one less grey hair for me--but I can tell when my FW needs oiling; it gets noisy in the bobbin area, and so does my Elna (1985 model) and those are mostly the only machines that I use with any kind of regularity. My LA gets cleaned and oiled before every use.