I'd be doing my own oil changes instantly. Issue is as stated, the timing of it.
After hours say 6pm-10pm or weekends 8am-6pm would be ideal.
Mon-Fri B/H too many are working and thus it wouldnt be a viable option.
Also the issue of workcover, insurance and everything else i think would be such an arse ache it would pump the cost up too much.
I mean an oil & pad change for instance won't take too long (couple hours). So $25/hr maybe?
Gonna be hard to make any money even with half a dozen hoists @ that rate.
There is also an issue of "what if something goes wrong" like you are changing manifold and snap studs, you can't just up and leave the premesis. You could end up waiting 2-3 days and all of a sudden its a $600 adventure where you could've just paid a workshop $600 to do it for you and you could be working for 3 days