Ah, I missed where you mentioned both cars being equipped with standard transmissions. Regardless, standard transmissions also have a lubricant that should be periodically replaced. In the case of the standard transmissions in your Corolla's the lubricant is a 75W-90 gear lube and that should be replaced every 50,000 miles for severe usage, to every 100,000 miles for normal usage. If it's never been done at 120,000 and 168,000 miles, it's well overdue. Old/worn out gear lube can allow a standard transmission to wear out, necessitating a costly rebuild.
I looked up your car on my companies Product Application Guide and to my surprise there is indeed no fuel filter listed, so apparently what you were told in regards to that is correct.
If the owners manuals for your cars are listing a drive belt, this means the engines are equipped with timing belts and not timing chains. The drive belt term is the factories terminology for a timing belt. Timing chains don't need periodic replacement, but timing belts do. Timing belts have various recommended replacement intervals from car manufacturer to car manufacturer ranging from 100,000 miles to about 150,000 miles and are a pivotal maintenance item. The timing belt is made of rubber and over time it will develop cracks, eventually snap and the engine will come to a stop. If you are driving in heavy traffic, this can be a dangerous thing to happen of course. The timing belt keeps the valve train and the crankshaft of the engine in time so the engine runs properly. Some engines are known as interference engines and what this means is that if the timing belt snaps, the valves and the pistons inside the engine can hit each other with catastrophic results, in many cases destroying the engine and costing thousands of dollars worth of damage. Of course, you don't want that to happen, so addressing the timing belt issue is tops on the maintenance list. Many vehicles have water pumps that are very easy to replace when the timing belt is replaced and water pumps don't last forever, so it is not at all a bad idea to replace the water pump as well, so you wont pay double for labor when the water pump eventually fails, (if it's not replaced at the same time the timing belt is). For example, if the labor for replacing the timing belt is $200 and the additional labor for replacing the water pump at the same time is $30, then the total labor cost for both jobs is $230. If you don't have the water pump replaced at the same time as the timing belt, when it eventually fails in the future, you'll have to pay the entire $230 labor again to have the water pump replaced, as virtually the same work that was done to replace the timing belt only will have to be done all over again. I hope I explained that so it makes sense? A typical timing belt and water pump replacement job is about $500 and the antifreeze will be replaced at the same time.
With the spark plugs, my personal recommendation is to at very least to remove them and inspect them at 50,000 mile intervals. If the spark plugs in your Corolla engines with 120,000 and 168,000 miles are the original factory spark plugs, they are way past due to be replaced, (look at the recommended maintenance list in the owners manual). With a vehicle, it's almost always less costly to be pro-active and replace maintenance item parts before they fail and cause further problems, such as the spark plugs. Old and worn spark plugs can't provide maximum fuel economy, easy starts, (particularly in cold winter temperatures), can lead to rough running, an increase in emissions, etc. Another problem with leaving spark plugs in too long is that the part they thread into, (the cylinder head), is aluminum, the spark plug threads are steel and leaving them in too long can cause corrosion between the steel spark plug thread and aluminum cylinder head to occur, making it very difficult to remove them. In some cases, so much force has to be applied to break them free that the threads in the aluminum cylinder head can become stripped and ruined. In the best case scenario, the threads can be cleaned up and a new spark plug installed and in the worst case scenario a new cylinder head will have to be installed, which can easily exceed $1,000. Considering a set of good spark plugs run around $30-$40 it can save quite a bit of money by simply replacing them on time and not leaving them in too long. With most 4-cylinder engines, (as with your Corolla's), the spark plugs are very easy to get to and might take about 30 minutes to replace.
Again, I checked the Product Application Guide for your car and fortunately for you it doesn't have spark plug wires, so you wont have to worry about that at all.
My Product Application Guide lists cabin air filters for your Corolla's and these filters filter the outside air of dust, pollen, etc., from entering the passenger compartment/interior of the car. If they have never been replaced, you can bet they are plugged up and are well overdue for replacement. A plugged cabin air filter not only restricts the amount of outside air that can center the car, but if so equipped it also puts extra load on the air conditioning system.
Brake fluid is another important but often neglected maintenance item. Brake fluid is a hydraulic fluid and when you push on the brake pedal, a plunger inside the braking system master cylinder compresses the brake fluid so that the fluid then compresses the brake calipers, which then pushes the brake pads against the spinning brake rotors, thus bringing your Corolla to a safe stop. Over time, brake fluid can become contaminated with dirt, discoloring it from a clear color to brownish in appearance. This can cause moving parts inside the brake system to stick, not function smoothly and in some cases, not function at all.
Another problem with old brake fluid is that it can become contaminated with water, which lowers the boiling point of the brake fluid and in a panic stop situation can allow the brake fluid to boil, which can allow the brakes to malfunction with the brake pedal becoming spongy/unresponsive and/or drop to the firewall without stopping your car. Bake fluid is hygroscopic which means it absorbs moisture from the atmosphere and the more water it absorbs, the lower the boiling point of the brake fluid. So how do you know if the brake fluid in your car is in good shape or not? With a color coded brake fluid test strip you immerse into the brake fluid that will tell you if too much water is present in the brake fluid. These test strips are available from better auto parts stores such as NAPA, Carquest, etc. I'd be very surprised if the discount auto parts stores such as Autozone or Advance Auto Parts had these available. Last I checked, they didn't. Below is a link to various companies that offer these brake fluid test strips. Call around in your area -
http://www.nextag.com/brake-fluid-test-strips/stores-html
Antifreeze; if it's never been replaced, it would be wise to do so. Ditto with the cooling system thermostat in each engine.
Cooling system hoses deteriorate from the inside out and should be replaced every 100,000 miles or so. Cooling system hoses include the upper and lower radiator hoses, as well as the hoses going to and from the heater core, which have just as much wear and teat on them as the radiator hoses do. Those heater core hoses can burst, leaving you stranded alongside the road with steam pouring out from under the hood.
Brake lines; as cars accumulate a lot of mileage, brake lines can many times rust and burst, (particularly in regions that have snow), causing the brakes to fail. Have them closely inspected for rust/corrosion and replaced if needed. Brakes are nothing to cut corners on.
Power steering fluid; this is another hydraulic fluid and it's at the heart of the steering system of your Corolla. It's another fluid that is commonly neglected. This is a shame, because power steering fluid also lubricates the rack and pinion unit which is the backbone of the steering system of a front wheel drive car. When and if they wear out, they typically cost $500++ to replace. Changing the power steering fluid with a $5 turkey baster to suck out the old fluid, and pour in new fluid from a $5 can of new power steering fluid is very cost effective. Do this a few times over several weeks and virtually all the fluid is replaced. You can have this professionally done at an auto center with an expensive flushing machine for about $80-$100. You pick. lol
Rust; have the car thoroughly looked at for undercarriage rust that will eat away at the major structural components of the car. Most cars hold up well against rust these days, but if rust is starting to appear and the issue is not addressed, it will eat the car from the inside out and long term will destroy the car when everything else on the car might be in fine shape. Most people don't address this issue as they only keep their vehicles for 100,000 or so miles, but for the long-term goals of 200,000 + miles that you want, rust shouldn't be ignored. Undercoating can be purchased in cans at most auto parts stores and sprayed onto any area's that are showing rust. Rust needs two things to spread; air and water, deny it either of these and you'll stop it. Sealing the frame/undercarriage with undercoating will prevent rust and also make the car a bit quieter as the undercoating helps to insulate against road noise.
So there you have it, a fairly complete list. Feel free to print it out and reference it for future use. Helping people's cars to run better, more reliably, at lower cost and lasting longer has been my profession for the past 25+ years. I hope this helps you out. If you have any questions, feel free.
