I have my vacuum pump for the past 6 years and I use it not very often. However I felt it was time for an oil change. It's very similar to changing oil in a car engine so read on for how I did it.
Step 1: How to Know the Oil Is Bad.
Normally the oil in the sight Glass is clear. Here you can see it is opaque. Hence the reason for the changeout.
Step 2: Preparations.
First I raised the pump by resting it on a storage box. Next I used an old measuring cup to collect the oil.
Step 3: Getting the Oil Out.
Below the sight Glass is a 3/8inch hex head drain bolt. Once slackened I finger unscrewed it.
Step 4: Draining.
Ah the murky oil. Drains completely in 5 minutes.
Step 5: Putting Back the Plug.
Using a magentic pick up I fished out the bolt and reinstalled it into the drain. This bolt needs a little torque to properly seal the drain.
Step 6: The New Oil!
Here is the brand new bottle of vacuum pump oil! I used a scissors to cut the tip and now for the next step.
Step 7: Adding Fresh Oil.
The fill cap is actually the vent cap. Once off the oil is filled to the level marker. Putting the cap back in place it's time for testing!
Step 8: Completion!
The pump works great now with the fresh oil. I should be good for another 6 years with the frequency I use the pump.
I hope this has helped you fellow air conditioning diy enthusiasts.