Cleaning and maintenance. Love the machine, Using it for making curtains and quilting. Having put

Question

Love the machine, Using it for making curtains and quilting. Having put some time in on the machine thought I should clean it...Followed manuals instructions. Machine is now somewhat noisy.Troubleshooting suggests inferior oil...I didn't oil it as there is no mention of oiling in the manual.What type of oil and where should I oil the Shark Intelli-sew 9110?It seems to be a closed system.