I don't have enough differential fluid on me at the moment to take out the plug and put the washer back on so would it be problematic to drive the car for a day without the washer? The earliest time I can put the washer back on is after work tomorrow at 6pm. Thanks guys.

 

As long as you have a good seal with the drain plug alone, you will be fine. Just don't let it get too low (and drive) if you're seeing seepage.

 

Sorry I did not quite comprehend "seeing seepage" at the end of the second sentence. I've torqued it to 33 lbs as stated in the guide so hopefully that'll help a bit.

 

The washer is what actually creates the seal. The head of the bolt will do so temporarily, but you should get the washer on there soonest.

 

Sorry that I was unclear. To be as precise as possible:

(Like SIIK2NR said You need the washer to create a seal. In my opinion, you are okay to TEMPORARILY drive the car without the washer as long as there are no signs of seepage (leakage) from the bolt.