AC Oil - Ester

[280EZRider]

In order to change a leaking hose on my AC, I need to drain, install the new hose, evac, and refill with R12. The oil in the York compressor is Ester mineral, but I have only been able to find synthetic Ester oil. (I can't imagine the 2 can be mixed).

Does anyone know where I can find mineral Ester oil?

Or: If I drain all the mineral Ester from Yorkie, would all seals need replacement for replacing the mineral with synthetic Ester oil?
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