Is the silicone oil used in a diffusion pump oil special?

I have obtained two diffusion pump stages from a pair of very old Vacuubrand high vacuum pump. The rotary vane pump in one of them was dead and another overheating. So, I salvaged only the diffusion pumps. I pan to set it up with a rotary pump to build my own high vacuum pump. The inside of the oil diffusion pump was quite burned up due to lack of proper maintenance. I cleaned it up with Toluene and detergent and now it’s almost clean.

I have presently have two types of rotary vane vacuum pump oils with me i.e., a clear looking hydrocarbon based mineral oil and another one is a brownish thick oil (could be polyester based or something). The latter is quite viscous also. I managed to borrow a rotary vane and tried using the brownish vacuum pump oil and it was a bad idea. Once heated the entire room stank. Took it apart and cleaned again.

My question is can I used the clear mineral oil or it must be a silicone oil? I currently only have like 25mL XT 704 silicone oil with me that a friend gave me. Is it mandatory that only this particular silicone oil must be used or any type of regular silicone oil will do the job?

Here are a few pictures of the oil diffusion pump (the second unit is also same) below: