What are the types of oil transformers used?

Power Transformers: Used for long-distance high-voltage transmission, typically oil-filled for better cooling and insulation.
Distribution Transformers: Employed in local electrical grids to reduce voltage to a usable level, often oil-filled for durability and efficiency.
Instrument Transformers: Such as current transformers and voltage transformers, used for metering and protection purposes, and typically filled with oil to ensure accurate and reliable operation.
Autotransformers: Utilized where voltage regulation is needed, oil-filled to manage high power with efficiency.
Hermetically Sealed Transformers: Used in environments where the transformer oil must be completely isolated from the atmosphere, to prevent oxidation and contamination.