I just wipe mine out with a paper towel and pull it through the end.
Me too.This is exactly what I do.
^^^ modified - I do that for all funnels regardless of fluid. I also might stuff a paper towel down it just cuz it makes my OCD betterThe question is how clean is clean enough the next time a funnel is put to use?For motor oil, I'll normally just wipe out with a clean rag. Sometimes I'll use some brake cleaner to clean off oily residue.
Wow! All this for funnels. ...

Don't wipe them with a rag if you're going to put oil in your engine. rags leave small amounts of lint you can't see and over time will accumulate on th oil pickup screen, use paper towels or clean solvent and blow dry with compressed air. Just in case you don't believe me, I owned a transmission shop for 40 years, several times I had guys who rebuilt (tried to) their own transmissions and more than once the complaint was after a few miles it stopped moving, more often than not they wiped parts with rags anf soon after the filter plugged up with lint.Just how much cleaning do you do on a funnel before putting it to use?
Background: I have a bucket of funnels, all plastic. The most common use is engine oil changes on our family fleet. Throw in various other fluid changes and fillings they see antifreeze, transmission fluid, brake fluid, water, gasoline, diesel, fuel additives and, once in a while, pesticide/herbicide. I try to at least wipe them out before putting them back in the storage bucket.
The question is how clean is clean enough the next time a funnel is put to use? For motor oil, I'll normally just wipe out with a clean rag. Sometimes I'll use some brake cleaner to clean off oily residue.
What does the crowd suggest?
I was afraid someone would think my OCD was bad...I'm waiting for the posts on autoclaving funnels
I throw an old bedsheet over them. Works wonders!your funnel rack needs a dust cover!