What do you do with the residue oil and brake cleaner that flow through?
Water, antifreeze, engine oil, hydraulic fluids. One funnel. Small engines gets a smaller funnel. Oil jugs drain into the oil squirt can. Funnel may drain back into an oil jug if the jug is not empty. I do not sweat over cleaning a funnel with a paper towel. My car has 600,000 miles on it with the head never removed. Yes I do not want to pour big chunks of dirt in an engine but if someone is worried about some little lint that gets washed into the sump, and then pumped into the oil filter if it did not settle to the bottom of the sump/pan. That seems like overthinking. Be cleaner working with injectors though.
I use two large and one small sizes of the special John Deere plastic funnels that have the screw-on caps on both ends. After use I don't even wipe them out; just leave a twist of paper towel in the small end, screw both caps on lightly, and set the funnel in a bucket with the others. By the time I want to use it again all the oil coating the inside of the funnel has flowed down and wicked into the twist of paper towel. No dirt or dust got in because of the caps. So that twist gets disgarded & the funnel is ready for use again.
I haven't cleaned a funnel since discovering that trick.
rScotty
I'll admit I thought this thread was geared towards OCD, but your post intrigued me. I found that JD labels Clean Funnel brand funnels, which I have never heard of until now. Here's a link showing a variety of their funnels: Keep Grit, Dirt, and Debris Out of Your Equipment with Clean Funnel! - Gear Up With Gregg's - YouTube
I always wad a piece of newspaper in the down the snout after I use a funnel and toss in a covered bucket with the rest of the funnels. The caps would keep things much cleaner, and I really like that they use standard sized caps that can be replaced with other household product caps if lost.