So I am trying to get my 2001 2.2L 5-speed manual Cavalier (265k) back on the road after it has sat in the garage for 3 years. Went to go buy conventional oil because I only have around 3 quarts in the open bottle of supertech that I had been using. Can't find it nor any conventional 5w30 oil anywhere. So my question is - what should I do? I have the 3 quarts left of conventional and only need 1 more - but the bigger issue is can I use "synthetic blend" or full synthetic in my old Cavalier that has never had anything but conventional in it?

Second problem - as you might not be surprised to hear even though the AC was ice cold and fine when I parked it, when I went to turn the compressor on the other day, pressure was so low that it didn't even kick on. Bought a $10 can of r134a, and was able to get it started to suck in until cold. Thought the problem was solved. Next day, go out - same thing - hot air from vents, compressor not kicking on, it had all leaked out in less than 24 hours. So my next question is - is there anything - like adding a can of that "oil charge", stop-leak, continuing to try more cans and hope that by running the seals will soften up again, etc.....short of an entire $1000-$1500 new compressor job to get it working again?

Third problem - go out to change the air filter. Find the black cover/housing thing that has the 4 big black screws - has cracked and only 1 of the 4 are now connected to anything or holding anything down over the filter. All other 3 have broken off so that the screws either broke off with the piece or are just left sitting there on the base not accomplishing anything. Is there something that you guys have rigged to hold the thing down? I searched for a bracket of some type but came up with nothing and I sure don't want to go the messy, sticky, duct tape route.

Thanks. I am sure I will find more problems as I spend more time on it.