I saw the video on youtube of a guy using car oil filter to make a ghetto filter for vacuum pump. I don't agree in his evaluation of the efficacy on his homemade contraption, it is only shielding the area from oil splattering out, but doing barely anything to actually filter the mist. I know because I bought the filter he recommended in his video and made the thing myself. Almost the same amount of vac oil mist was generated as without the contraption. For me the DIY filter did not do much to reduce noise either, I don't know if a real filter will do much.
I run a noisy refrigerant recovery pump and what I did was build a silencing box around it consisting of 4 layers. Inner layer has mass-loaded vinyl, then a layer of 1/2" particle board, then a layer of acoustic caulk, then another 1/2" particle board over. The box has ventilation holes where appropriate, and where the holes are, I placed a baffle consisting of two 1/2" particle board with acoustic caulk sandwiched between. It makes a big difference in sound. Now the sound is dampened to less than a household vacuum cleaner.
Btw if conservation of water is not an issue, consider looking at a faucet aspirator to pull vacuum.