I do know that the kind of lift I would want, would mean the garage built around it would be so large as to ruin the look of "The Cabin" nearby. So, I'm changing my transmission fluid on a flat section of pavement on the east side of the property. The question is, have I made too many car choices based on whether I can work on it or not, as opposed to liking the way it handles?
I have a quick jack. I probably have the room for a two post but I didn't want to take up the space and I'm not constantly under the car. (Hopefully). It worked great as I removed all the undercoating and rebuilt the suspension and drivetrain. I bought it from Home Depot for around $1500. The lifts hang on the wall for storage and it uses a small 110V hydraulic power pack.
Someone has already mentioned it, but if the garage floor wasn't designed for a 2 or 4 post lift with proper footing/thickness, that's remedial work that has to be done prior to installing the lift. One of the lift-table types might be a better choice in that case, particularly for more casual use.
My father's first auto repair shop started out as a florist shop. He installed a 2 post lift back in '82 and never had any issues until retired in 2005. Ceiling height was only 10 foot, so you couldn't stand up straight beneath the vehicle unless you were short (my father was 5'9"), but it was adequate for more than 23 years. I don't think anyone ever knew how thick the concrete was, not likely very thick, but it never buckled, cracked, nor showed any stress with the lift.
Safety is very important, but if you are only using it on your own vehicles, there is no reason to over-kill the project. A 4 post is more versatile, but you aren't running a repair shop where you will see 50 different vehicles per month. A 2 post is fine and is all I would consider.
I will add my 2 cents here because I have some experience with the subject matter. First off, to @Nubs , as you are just getting started in car tinkering a lift like the one posted here from Costco should be fine. (Great job with the oil change! You should be proud of that. A lot of people have no idea how to do it!)
As far as lifts in general, the two post lifts are the most versatile for working on cars. The four post lifts are great for storage, but take up a lot of floor space and get in the way of a lot of repair jobs.
When I put a lift in my shop, I found that most two post lifts were just over twelve feet high. You can get low ceiling lifts, but then the cables go across the floor under a plate, and that gets in the way of things like transmission jacks. So I built my garage with a 14 foot ceiling. I installed a Rotary brand lift. Their recommendation for concrete was 4” for lifts up to 7,000 lbs and 6” for 10,000 lb lifts. Mine has been installed on a 4” slab for over 20 years with no issues.
Here is my son (only 12 yo) working on my car. He can do almost all the general maintenance stuff to a car already!
Correct, with one clarification-
The recommendations by the Automotive Lift Institute (ALI, 75 years the standard) state a minimum of 4" or 6" reinforced concrete for those applications. They also discuss slab continuity, joint locations, etc.
The ALI publishes some very thorough guides on installation and operation, and has a comprehensive website. https://www.autolift.org/
In 45 years of auto service using both in-ground and above ground lifts, I have seen lifts fail from overloading, mis-loading, mis-use and wear/maint issues, but I will admit to never seeing a failure due to floor structure. (But all were installed in purpose built shops too) I wouldn't skimp on safety however, and would bet on limited insurance coverage for an installation that fell short of recommended standards.
But while I can justify the need for being able to stand up underneath vehicles every day, I am left wondering about the OP's cost effectiveness and actual need here after reading through the thread...
If the OP is looking to learn about cars, do their own basic maintenance, a lift to get the up so you can walk under it is completely unnecessary. Overkill. Nice to have for many of us but not required. I've been working on cars since I was 16. 51 this year. Everything under there has come out at some time or another. Replaced or rebuilt. Engine, tranny, driveshafts, axles, clutch, suspension. Whatever. I have never had a lift. Floor jacks and stands. I still do that. I would love a lift as I get older and still want to do this. Getting down, under and back up again will get harder as age settles in. In reality, my double car garage has too low of a ceiling. I can't. Plus add the overhead chain drive electric garage door openers, even the quick jack is questionable for my needs. I run older cars. They are not low and sleek. See my avatar. I may go with the quick jack for ease of set up and safety. Still pondering one all these years later. Again, not required.