What does my car need?

[MMMdude]

Besides oil changes, new battery and tire rotation to my car, I have not really done anything for it in the last couple of years/50,000 KM's (30,000 miles).  I have a 2000 Celica and the thing runs great and is at 230,000 KM's.  I want to catch up on maintenance I've been neglecting.  What are the things that are critical?  Spark plugs have never been changed - is that necessary or only if there are symptoms?  Car still gets 30+MPG as it always has.  Brakes are good.   Goal is to keep car at least another 5 years.

[CALL 911]

It sounds like there's a lot you've neglected. You don't mention what was done before the last 30k miles, so . . . Off the top of my head: air filter, fuel filter, coolant, transmission fluid, spark plugs/wires, distributor cap/rotor, wiper blades, brake fluid, serpentine belt . . .
Not all of these will need to be done, but without more info, I can't tell you what is in a state of neglect. And when you say the plugs have never been changed, I'm guessing you mean recently. Plugs wear out, and if it still runs at 230k with the factory plugs, that'd be a minor miracle.
Basically, I would recommend going to ebay/half/amazon and getting the Haynes manual for your car (used of course). Routine maintainence is right in the front. Good luck! You can do it!

[Jamesqf]

First thing to do is to download the owner's manual for your car, and find out what maintenance is required.  It can differ a lot between models, as for instance my Honda recommends changing spark plugs at 105K miles, doesn't have a distributor cap, etc.  Some others recommend things like changing the timing belt at intervals...  You can't really go by general rules any more.

That said, the one you probably should do right away is the air filter, if you haven't been changing it as part of the oil change.

[bogart]

If your car has a timing belt, not  a chain, and if the belt breaks, it is entirely possible that will cause more damage to your engine (in terms of cost to fix it) than the car is worth (given its age and mileage).  This, in turn, depends on whether the 2000 Celica has an interference or a non-interference engine; the latter would be the better alternative in this regard and a quick Google search suggests it may (also that it may have a timing chain) ... but ... if either of those isn't true, I would get the timing belt changed pretty much immediately. 

The other things people are describing will affect the car's performance, and some could break or otherwise malfunction in a way that would leave you stranded and therefore be annoying.  But a broken timing belt could ruin your car.

You can read more about this general issue (car maintenance) in this thread:
https://forum.mrmoneymustache.com/ask-a-mustachian/diy-vehicle-maintenance/msg45212/#msg45212.

[GoStumpy]

First things I can think of are fuel filter to prevent a fuel pump failure, spark plugs to prevent ignition system failure, timing belt/chain to prevent catastrophic failure..

Most forget that when spark plugs 'wear out', they really are just increasing the gap, requiring more and more current to generate a spark... on vehicles with coil-packs, this will burn out the coilpack long before you realize that the spark plugs need replacing... I've had two work vehicles have that failure, both had 180k+ km on them... the Econoline had over 300k km's... original plugs.

Instead of replacing plugs for ~$50, we had to replace a bunch of coilpacks @ ~$150 each... plus labor.

[thurston howell iv]

Inspect the timing chain. If it feels loose or has slack then change it. Otherwise if it looks good you should be ok. Of course all of the other filters, plugs and such should all be changed and the remainder should at least all be inspected. Sometimes it seems like it's all working fine and upon inspection you'll find issues. Preventative maintenance is always cheaper than having something break.

[BlueMR2]

My wife's got a 2001 Celica GT (1ZZ-FE engine) and it's got a timing chain with a 100,000 mile check listed.  Definitely don't want the chain to break on you.  From what I can gather, all the Toyota engines are non-interference, so you wouldn't have the valve/piston contact issue on the chain breaking.  However, what you will have is the chain acting like a buzzsaw tearing up everything under the hood it can hit during that short period before the engine stops...