The Wahl 5 in 1 has: #9, #10, #15, #30, and #40 blades
https://www.petedge.com/zpetedgemain...8655A0AFEC2FB3
For blades, the higher the #, the shorter the cut. You're correct, #40 is considered surgical blade, vets use this blade to shave down for surgical prep. It can also be used under combs (also #30). Groomers use it for Show Poodle trim, but it's safest to use a #15 against the grain.
If you're wanting to clip their body w/blades, I recommend getting a trimmer w/separate blades. Bc you can't use the cordless 5 in 1 style to trim their body (unless you use the combs), the blades will leave too little hair on the body, even w/ a #9. Unless it gets really hot & humid where you are & they have thick hair. Silky thinner haired pups will look shaved w/a #9 (which is the longest blade in the 5 in 1). Might cause clipper burn & irritation, even sunburn.
To trim their body, I use my Andis w/a #7FC or #6FC blade for my thick cottony soft furball Momo & #4FC or #5FC for my other 3 w/silky hairs.
The Oster you linked looks just like the Wahl, but it has a lower motor power. So I would think it would be louder than the Wahl & vibrate more, but not much. The Andis set you have sounds like a good set...are the blades dull? You can send them in to get it sharpened or google 'clipper blade sharpening' in your area. If nothing is wrong w/the blades, then maybe all you need to do is get a new clipper.