Put your device on a dry cloth Take a hair dryer and start warming the speaker for 5 mins Then, there are many websites online that play a specific sound and remove dust and other things. So this should remove it. After one week, or two I'm sure ur speaker will be fine. This worked for me, saying from personal experience. Water went into the mobile speaker If you find this helpful kindly click on the three dots and click accept as solution
Since u r talking about oil, I think it's better to take it to a service centre. Drying it with cloths n rice won't help coz it cannot dry the oil completely. (Normally a few drops of high % propyl alcohol can be used to dry but it's not suitable for oil I think. ). Better to take it to a professional.
