Fluid Change and oil leak in 1999 Cadillac Eldorado
Your best bet would be to take it to a shop to have it changed. Some of the fluids are simply too difficult to be removed without professional help.
The oil can be changed by loosening the bolt on the oil pan under the car. While down there you can check to see if the gasket around the oil pan is leaking oil and you can check the tightness of the oil filter. If that's not it, maybe a head gasket problem? If you take out a spark plug and there's no oil on it, that's probably not it. I know my Eldorado uses a quart of oil a month, as did my Deville which was also a Northstar. Rather than spend thousands to replace every seal and gasket, I pay $5/month for a quart of synthetic oil (which I recommend as it doesn't break down as easily by the heat, has more lubrication and lasts twice as long). My cousin, who is a mechanic, also told me that oil can be burned and piped out of the exhaust, which is why I never saw drips or leaks.
Coolant is another fluid you should change. I just did mine but I could not find the petcock (drainage valve) for the life of me. I simply removed the lower radiator hose (while the coolant is cold!) and drained it in a bucket which I later threw on my neighbors lawn (kills the grass, to get back at the barking dog). Anywho, make sure you use DexCool, the orange stuff, when refilling the radiator. 60/40 mixture of coolant and water. I ignore that and pour the whole thing in and think whatever I couldn't get out will help dilute it down. I also use AlumaSeal to prevent any leaks. I add the aluma seal to the upper hose before adding the coolant. I also check the coolant cap to make sure it's not corroded. That's a $5 part that can quickly depressurize your system and make you lose $10 worth of coolant and possibly strand you and your car.
Transmission Fluid - take it to a shop. For about $80 they have a machine that pumps the old stuff out and the new stuff in. I used synthetic once ($200 for 15 bottles!) and it lasted a day - they screwed up one of my transmission hoses at the shop that added it and it all leaked out. The cheap stuff probably works fine, and at the very least if you don't replace it you should "top it off". Drive the car around (or warm it up and switch from gear to gear spending 30 seconds in each) and check the dipstick. It's a pain to get to under the air filter assembly.
Brake Fluid - you can take off every tire and bleed your brakes one at a time, making sure the brake fluid level is never completely empty (otherwise you will get air in your system), or as one of my friends used to do just use a turkey baster and **** the old stuff out and put the new stuff in. I use Prestone Dot 4 despite their dire warning it only takes Dot 3. Dot 4 is more resistant to heating up.
Power Steering Fluid - the turkey baster approach again or take it to a shop to have it drained for you. I've never figured out a way to completely flush the entire system at home and it looks like something I wouldn't want to bother with.
AC - you can charge this up with a little $30 bottle and gauge from Walmart and it has a lubricant for the a/c seals too. Works great, you simply shake the bottle like it's a baby and you are a British nanny, snap the gauge onto the nipple located in the middle of the car (I think it has a blue cap - there are only two nipples and it will only fit one), turn it upside down and inject it in. I can't remember if you pressed down on it or if it had a valve or button, but you inject enough until the pressure is within the parameters specified in the owner's manual. I'm not sure of the psi off the top of my head.
If the car hasn't been started the gas may need to be checked for it to start. I put a product called "Sea Foam" in the gas tank to help clean the injectors - it's about $9 at Walmart and works far better than those STP gas additives.
I'd also check tire inflation and make sure the fluid in the battery is good (as well as the battery itself) before driving it.
