Can I use synthetic motor oil for a very old industrial sewing machine which has a oil tank

Foot pedal or speed control is sticking. Open it up and apply grease or do whatever you have to to restore smooth fluid operation.

Unless the machine is rusted, liquid Tri-Flow Synthetic Lube and heat from a handheld hairdryer (or setting in the hot sun) will most likely loosen things.

Has it been oiled lately? If not, it could be seized. Old oil turns to glue and then varnish unless it is regularly maintained. Make sure to use only fresh, good quality sewing machine oil or liquid Tri Flow Synthetic Lube. Slowly rock the hand wheel and apply a couple drops every place where metal rubs against metal--no oil on belts, rubber, synthetic parts! If it is still resistant, direct hot air from a handheld hairdryer into the internal mechanism and repeat the process until things are loosened and moving smoothly again.

A sewing machine should be cleaned and lubed every 40 hrs of working time or every 6 months if not in use.

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Is it an older mechanical machine (not computerized)? Bet it needs a good oiling. Old oil will dry out and turn to glue/varnish and actually prevents parts from moving and dragging on the motor. Use only fresh good quality sewing machine oil or Tri-Flow Synthetic Lube. Open the top, left side, and bottom of the machine. Slightly rock the handwheel and apply 1-2 drops of oil every place metal rubs on metal. Do NOT oil rubber, leather, or synthetic/nylon parts.

If it is still sluggish, you can direct hot air from a handheld hairdryer into the interior mechanics of the machine to help loosen things.

Older machines do need frequent oiling--ie, every time a new sewing project is begun or every six months if not in use. If a large project like a quilt, more frequent oiling may be needed. When you become familiar with the pleasing sound of a well-running machine, you will recognize when it needs some TLC.

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It needs testing the power supply.

You need to be able to tell us what brand and model machine you have. There are identifying tags or engravings that will give you that information.

You can download a manual here:
https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0CB8QFjAAahUKEwiYp7yAjbHHAhWKWpIKHYkkAYw&url=http%3A%2F%2Fwww.raichert.com%2Fadobe%2FMO804-12-16%2520Inst.pdf&ei=hlfSVZjMOoq1yQSJyYTgCA&usg=AFQjCNH1vfonoEQ29McTsOItvQoW8ECZag&bvm=bv.99804247,d.aWw&cad=rja


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That's correct. NEVER use 3-in-1, WD-40, cooking oil, or old sewing machine oil you found in your grandmother's sewing box!!! Also, do not try to force the motor to run when the parts cannot turn freely.

You might try picking up a bottle of liquid Tri-Flow Synthetic Oil at the hardware store (or order online). It is a penetrant that will help loosen up the goo. Then, try directing hot air from a handheld hairdryer toward the area that you have oiled. Get the metal parts warm/hot (but don't burn yourself). Let cool and test, then repeat if necessary.

You can try cleaning out the goo to get it out of your machine, but it may take repeated attempts.

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Because I expect you are using it for home use I will tell you this. Users of this machine may have a mess from the oil pan. Take the oil pan off. A man I worked on began to use synthetic grease on a regular time frame such as 100000 stitches. This prevents the mess from the oil pan. It appears as a powder but will adhere to the gears. I wouldn't use synthetic motor oil because it doesn't stick too well. Anyway, this is only a suggestion. The nice thing about this is it comes in a spray can at Walmart

check with bernina to see if the machine has a hidden fuse & if it doesn't then the machine needs to be serviced

Industrial sewing machine oil is usually not brand specific but is not interchangeable with automotive motor oil or thinner lubricants. Do not use WD40 or similar type lubricants as a substitute! Check with a local sewing machine repair shop or order online from Amazon.com (search for industrial sewing machine oil) This type of oil should cost less than $15 for 16 oz (before shipping)