@Namenick thicker lubes are better for firmer holes and thinner lubes are better for softer holes. You can always thin out your lube by adding a few drops of water or thicken your lube by leaving some of it out in an open container/with the cap off.

@Namenick  What has been mentioned already is that you can take thicker lubes and water them down accordingly to your tastes or to help lengthen the life of a lube bottle. Although don't overdo it. I ultimately like the Maria Ozawa lotion best. Slight floral type smell but otherwise it's the perfect thickness/viscosity for what I like. It feels very realistic. Sadly this has been out of stock for some time and I find the Meiki Bliss lube the next best thing and no smell. The Pussy Juicy lotion is good too, slightly thicker though. I advise taking advantage of a lot of the sample lubes included with many onaholes to try out others. The Noma Sotei Lubes were pretty good. But the ZXY and Sarah Lubes IMHO were too thick. It was almost like KY Jelly which I never took too. Honestly it's about trying different ones and experimenting on how much works best for you on dual layer vs single layer or softer onaholes. I usually try to only use a pea sized drop. Maybe two tops if I'm just getting started. Ive noticed tighter onaholes require more lube or a stop and relive moment because of absorption but usually 1 drop does the trick.

@Namenick  AFAIK, higher viscosity means it's thicker, and more slippery. Meiki Bliss Lotion is thicker than Tomax's Insomnia Lube. If you want a longer fap session, it's best to go with higher viscosity. It will reduce your sensation a bit, but will last much longer. Also, you can easily thin down a thicker lube with a drop or two or water / spit (this is also a good way to rehydrate it after a few hours of fapping).