After dumping the oil for a change the other day on an 8004 AJQ (CFWA), I realised that I didn’t have the right size socket for undoing the oil filter cap, and was unable to get it off with an adjustable wrench (I suspect the last person to do it either slipped the O-ring into the thread or massively over-torqued it).

I ended up considering the position of the filter vs the sump height and decided to fill up with new oil as it seems the filter can be changed with the sump full, and delay the filter change until I have the right socket this week.

 

Have I made a mistake here? Will I be able to open the cap and change the filter without all the new oil spilling out everywhere? If I need to re-dump the new oil into a clean pan and put it back in after I will - hence the question.

You'll be fine doing that.

No problem you will loose the filter oil amount but that's it, the only downside the oil will now look dirty from this old filter, these caps are not over tightened they are plastic and when heated up this happens this is the joy of owning  a decent socket set 

Thanks for the info. I figured the small amount of old oil in the filter should hopefully not be a huge detriment mixing in with the new stuff (xx mL vs 4.3L).

 

I've heard that having the engine hot may help getting it undone if the socket doesn’t help, but fingers crossed!

A 6 point socket is the better option, even when torqued correctly they can be quite stiff