When to replace items on your car

By glblguy

Four Pillars from Quest for Four Pillars caught me online the other day and asked me: How do you know when to change your tires? He knew I had a huge interest in cars and some knowledge about them. I of course replied and told him about tread wear indicators. We both thought that an article describing how to know when to replace the various items on your car might be of interest.

I’ve had an interest in cars since as far back as I can remember. It must be inherited as both my Dad, his brother and my Grandfather on my mother’s side were also huge car fans as well. Growing up around all 3 of them and in particular my dad, I learned a great deal about how to maintain and repair cars. My best friend and I in college rebuilt a 1966 Mustang he owned. I wouldn’t call it a full restoration, but we did turn a non-running worn out old Mustang into a good looking and reliable car…Although I hated the large gold rims he decided to put on it…

Here’s my perspective on how to know when to change/replace various items on your car or truck:


Tires are actually pretty easy as most, if not all, new tires have tread wear indicators. Tread wear indicators are bars made of rubber lying cross ways in your tire’s tread. You can’t see them easily on new tires, but as the tread wears down, they become visible. If the tread wear indicators are easily visible or even with your tire’s regular tread in more than two places, it’s time to replace your tires.

Another technique you can use is to wet your tires down, then drive forward (or backward) over a dry area of your driveway or parking lot. Examine the marks left behind by the tires. If you see horizontal bars cutting across the pattern, than the tread wear indicators are visible and the tires should be replaced immediately.

If you’ve rotated your tires as recommended (every 5,000 miles), than chances are if one tire is worn, the others are as well. It’s generally recommended that you change all four tires at the same time rather than just one or two.

Tires are expensive, but you can generally predict based on the predicted mileage of the tire and your driving habits when they will require replacement. This will allow you to budget and begin saving for replacement tires well in advance.

Oil and other fluids

In order to keep your car in good running condition and avoid unnecessary wear and tear, keeping your cars fluids changed is critical. The following fluids need to be changed:

  • Oil – Every 3,000 miles or 3 months is the general golden rule, but consult your owners manual as many new cars can go 6,000 miles or more between oil changes.
  • Coolant – Green: 2 years/24,000 miles, Long Life (pink) – 5 years/50,000 miles.
  • Brake fluid flush and power steering fluid – Every 2 years or when dirty or discolored.
  • Automatic transmission fluid – Every 60,0000 miles. If you pull a trailer or drive in mountainous or hilly terrain, you may need to do this more frequently, say every 30,000 miles. A reliable mechanic can inspect your fluid and advise you on when it needs to be changed.

Shocks and Struts

Shocks and struts provide damping to your vehicles suspension. In other words when you hit a bump, it keeps your car from continuing to bounce and provides a smoother ride. Unfortunately there is no hard and fast rule on how often you should change these items as they wear primarily based on use and weather conditions.

Most manufacturers will tell you that shocks need to be replaced 30,000 to 40,000 miles and struts every 50,000 to 60,000 miles. The real truth is that there is not specific interval. One easy test is to bounce your car by pressing on the front and rear bumpers. if the car bounces up and down more than 2 or 3 times, your shocks or structs might need to be replaced. The best way to tell is take your car to a mechanic you can trust, and they can tell you and look for potential leaks.

Unsure whether you have shocks or struts? Consult your owners manual. Most new cars have struts and most older cars have shocks, but it depends on the type and model of your car or truck. A strut looks like a shock absorber surrounded by a spring as it is all one unit. A shock is a separate from the spring.


There are four primary filters that need to be replaced on your car: oil filter, air filter, fuel filter, and transmission filter.

  • Oil filter – Should be changed with each oil change, so every 3,000 – 6,000 miles
  • Transmission filter – At 30,000 miles, 90,000 and 150,000 miles
  • Fuel filter – Every 35,000 – 40,000 miles. This is an important maintenance item that is often forgotten or overlooked. A dirty or partial clogged filter impacts your performance and gas mileage.
  • Air filter – Most places that do oil changes will check your air filter. Like shocks and struts, there is no hard and fast rule. The air filter should be changed when it’s too dirty. This is often a “gut” call based on how darkly colored the filter is. Changing the air filter is also a very simple maintenance item that you can do yourself. An oil change or mechanic shop will generally inspect your filter for you if you aren’t sure how to tell. Again though, make sure they are trustworthy!

Spark Plugs

Spark plugs are an item that on older cars required replacement every 30,000 – 50,000 but new cars use platinum and other long life plugs and can go for 100,000 to 200,000 miles before needing replacement. Consult your owners manual for the recommended change interval and if you have an older car, consult with your mechanic or do a search online for the make and model of your car.

Regardless of mileage, if your car is idling rough or seems to be missing (not running smoothly when driving down the road) check your plugs and spark plug wires or take your car to a mechanic. Problem wires and spark plugs are a common performance issue with cars and like a dirty fuel filter can impact your gas mileage.

Timing belt

Cars that use a timing belt require the timing belt to be changed. The consequences of not doing this can be significant. If the timing belt fails, your engine can lock up and be be completely ruined. The replacement interval for timing belts varies. You should consult your owners manual or your mechanic for specific time frames. In general, most timing belts requirement replacement at or before 100,000 miles. If you purchased a used car that has 100,000 or more miles on it and you cannot confirm whether the belt has been changed or not, get the belt replaced. It’s not worth the risk.

Have I missed any items? How often do you do maintenance on your various items on your car? Any tricks or tips you can share? Add a comment!

Photo by: {dpade1337}

8 Responses (including trackbacks) to “When to replace items on your car”

  1. MoneyGrubbingLawyer Says:

    From one gear head to antoher, great post! The only think I would add would be differential fluid for anyone with a RWD/AWD/4WD vehicle.

    I find the best way to know when something requires attention is to know your car. That’s part of the reason why I like doing my own work- I know my cars better than anyone, inside and out. When something is not right, I know before the big problems start.

    Many of the items you’ve got listed can be accomplished by the DIYer with a few tools and a decent shop manual (i like Haynes for most makes, the Bentley for VWs). Oil, changes, , all the filters, and plugs are fairly simple tasks. Coolant and tranny fluid are a little more involved but doable without any extra equipment.

  2. Wholesale Says:

    Great article.

    One thing you guys should watch out for is when you’re changing your radiator coolant make sure you get a premixed 50/50 from the auto parts store or mix 50% antifreeze with 50% DISTILLED WATER.

    This is huge, I’ve had this destroy both my radiator and wear on my engine. The metals found in regular water can actually cause your radiator and engine parts to rust and corrode. If you use DISTILLED WATER you won’t have to worry about any metals in the coolant.

    Just my 2 cents.. Great post.


  3. Laura Says:

    This is a great post! I always wonder myself about when to check for replacement. My car is 8 years old and I want to keep it running well.

  4. Four Pillars Says:

    Thanks again for the tire info!


  5. Roger Hamilton Says:

    Thanks for the info! Do you know of any other place to find such information?

  6. The Debt Helper Says:

    Thanks for the top tips. I have a gauage for measuring tyre depths so i know when to replcae them but your tips about Oil and Fluids was very very helpful. I’m not that hot on cars but this really does seem to make snse, thanks again for a useful article

  7. Make Friends, Earn Money Says:

    I have a Peugeot, a french car which uses a timing belt and i found to my cost that failing to replace it is a major problem. Usually they need replacing after about 70,000 miles and the bill to replace them is quite small compared with the one that I had to pay to fix the mess that it left my engine in when it broke (around $1000)