I found this works for me, you know them plastic water bottles with the pull tops? the right size caps screw right on a oil bottle, water or other which makes it easy to add oil without a big mess, works great on my ATV and lawn mower, any place where its tough to get to without spilling all over especially when adding ATF in your car or truck.
ive used one on a chaincase oil bottle to service my snowmobile chaincase which is in a tough spot to get a funnel in there.
It works great to top off antifreeze in snowmobile coolant reserviours.
Its handy when adding distilled water to boat and auto batteries.