A couple of CUPS of oil???
You're wasting all but about two tablespoons...the rest is ending up in the holding tank, where it puts a lovely "oil slick" on the surface that makes odor a lot harder to get rid of.There's a much easier way to lubricate the toilet than the never-ending battle of pouring oil down it every week or two...and it only takes about 10 minutes every spring as part of recommissioning: buy a tube of thick teflon grease, available at any bicycle shop. Remove the top of the pump...depending on the age of your toilet, that requires either removing 6 screws or loosening one hex nut. Put a HEALTHY squirt of the grease inside the pump...pump and few times to spread it all over the inside of the pump cylinder. Put the top back on. You're good to go without any need for any additional lubrication till next spring.Or, you can keep large jugs of oil onboard and pour some down the toilet every week...your choice. But I'd make it mineral oil (baby oil is mineral oil, btw), not vegetable oil, 'cuz mineral oil won't turn rancid in the summer heat.Btw...vinegar doesn't do a thing to lubricate a toilet. A cupful flushed all the way through to the tank prevents sea water mineral buildup in the head discharge hose.