My ‘secondary’ laptop – an A1181 white MacBook from 2009 – only officially supports up to OS X 10.11 (‘El Capitan’).
Using the super-easy, user-friendly patcher tools from dosdude1, I was able to force this machine onto macOS 10.14.6 (‘Mojave’) in line with all the other Macs I am using.
Some trackpad functionality has altered a little (I was warned this could happen on these models when I downloaded the patchers) but that’s still very useable. With an SSD now installed as well, the Mac runs impressively smoothly for its age.
Ideally I would like to boost the RAM up from 4GB to 6GB (which is the actual maximum RAM for this model, according to Everymac), but that will require finding a 4GB DDR2 SO-DIMM at a reasonable price, which seems to be almost impossible! Do please let me know if you spot any for sale, if you have any which you are no longer using!