Car won’t start after changing oil is a common issue that several car owners have been facing after replacing the motor oil.
Engine oil does a lot of things for the engine, but one of the most important things is to keep the moving parts clean. As the oil sludge builds up, the engine can seize or lock up completely.
This guide will list down all possible reasons that cause failure in starting your car after changing the oil. So, let’s get started.
So, why a car won’t start after changing oil? A car not starting after an oil change often indicates a weak battery, stuck starter, or wrong oil viscosity. If the car cranks but won’t start, check for fuel pump whirring noise. Stripping ground wire insulation during the oil change can short the system and prevent starting. Proper diagnosis identifies causes like battery, starter, oil viscosity issues or damaged wires from oil change service.
Before diving further, you have to first make sure that you do not overfill the engine with motor oil. Remove the plug from the oil pan beneath the engine and drain out the old oil.
Also Read: How far can you drive on minimum oil
Table of Contents
Can An Oil Change Stop Your Car From Starting?
Yes, Your car can stop running and won’t start after an oil change if the oil has a different viscosity and does not match the specifications recommended by the car manufacturer.
Bonus Read: Oil leaks when car is parked
These days, modern GDI (Gasoline Direct Injection Engines) have much tighter tolerances compared to older engines.
Moreover, due to GDI technology, synthetic motor oils are preferred in modern engines as synthetic motor oils have special additives to maintain their viscosity at high temperatures, keep the engine clean and prevent any engine sludge. Read my guide on best oil for high-mieage engines.
Also, if you have not correctly installed an oil filter after an oil change, it would also cause some issues while starting a car. I have explained this in my guide on 5.3L engine common oil leaks.
Car Won’t Start After Changing Oil
If the car won’t start after changing the oil the actual reason might not be directly related to the oil changing procedure as the issues in the car can occur at any time.
So, based on my experience and asking several people who had faced car starting issues after oil changes, here are the most common causes of the car won’t start after oil change:
- Dead Or Weak Battery
- Bad or Stuck Starter
- Wrong Engine Oil
- Overfilling Of Engine Oil
- Clogged Oil Filter
- Damaged or Improperly Fitted Drain Plug Of Oil Pan
- Damaged Fuel Pump
- Damaged Wiring To The Ground or Sensors
You can also read my guide on check engine light after changing oil and how to reset it.
1. Dead Or Weak Battery
A dead or weak battery does not have to do anything with the oil change, but it is the first thing you should check if your car is not starting.
Your car may be suffering from a weak battery. It could be anything from a bad battery connection, to a worn or loose battery terminal, to a weak battery. A weak battery can still display lights on the dashboard.
Try jump-starting your car. If it starts, there is an issue with the car battery. Also, check if battery terminals are clean and properly fitted.
Now, to test a car battery, people make a big mistake. They don’t test the battery under a load.
Without load, a voltage test on the battery can give perfect volts i.e. around 12V. But, to check the health of the car battery, you have to test it under load as the voltage across the battery terminals significantly drops when it supplies current to the starter.
Have someone try to crank a car and you should check its voltage using a voltmeter. If it is less than 9.6V, you should change your car battery.
2. Bad or Stuck Starter
Sometimes, a bad starter also causes a car not to start. You were wondering if the starter hasn’t anything to do with the oil change procedure, then why I am mentioning it here? Well, the starter can get stuck sometimes, which can prevent the car from starting. It is a usual issue that can happen anytime.
So, first, have someone hammer a starter while you are trying to crank a car. One user had faced a car not starting issue. His car started again after hammering the starter.
If the car still doesn’t start, you have to check the starter connections and pull out the starter to test it. You can read my guide on car starting intermittently. I’ve explained the diagnostic procedure of the starter and its connections in detail in that guide.
3. Wrong Engine Oil
Using a wrong engine that is not recommended by the car manufacturer also causes failure in starting the car after an oil change.
In my guide on the best oil for 3.5 Ecoboost, I’ve only listed the motor oils that meet the specifications of the oil recommended by Ford.
If your engine previously used conventional motor oil in your engine, you should use conventional motor oil. If it uses synthetic motor oil, you should use synthetic one.
Also Read: Low oil pressure at idle
Remember that even if synthetic motor oil and conventional motor oil have the same weight, they have different flow characteristics and lubricating and cleaning abilities due to differences in additives and the nature of the base oil.
Moreover, always prefer the recommended weight of the motor oil. Gone are the days when thicker oils like 10w30 or 15w30 were used in the engines. Now, engines have tighter tolerances.
One person added 15w40 oil to the engine. 15w40 is pretty much thicker at colder temperatures (when the engine is being started for the first time) than the 5w40 motor oil.
The oil pump has to work much harder to deliver 15w40 from the crankcase to the engine oil galleries when you’re trying to start the engine.
Engine oil, which is thicker during cold starting, makes it hard for the crankshaft to turn over and thus, prevents the engine from starting.
So, using motor oil of different weight will cause your car not to start. You can read my guide on SAE30 vs 10w30 to understand the viscosity of oil and its pumpability.
4. Overfilling Of Engine Oil
If the engine is overfilled with oil, it can cause failure in starting the car. This is because when engine oil is overfilled, the fast rotating crankshaft comes in contact with the oil. This will cause the oil to foam. This is detrimental to the engine as it pushes air bubbles into the engine.
Moreover, overfilling of oil can also cause oil to leak through the valve cover seal and gasket due to excessive oil pressure.
As a result, the oil will enter the combustion chamber and damage the spark plugs. Your engine seals and gaskets can also damage if the oil will be forced to pass through them
When changing oil, I would recommend you not simply pour oil into the old oil without draining it.
The old oil eventually turns bad when the time arrives to change the engine oil. While changing oil, allow the old oil to fully drain in an oil-safe container.
That old oil has all sorts of impurities, from running throughout the car to lubing the moving components within your engine.
When adding the oil, always check the owner’s manual for the recommended oil capacity (quarts) of an engine.
After you change the oil, make sure to check its level using the dipstick. Park a car on flat ground.
After a few minutes of filling the oil, take out the dipstick and clean it with the towel. Reinsert the dipstick and take it out. The oil should be lined up with the full marking on the tip of the dipstick.
5. Clogged Oil Filter
Vehicle manufacturers recommend changing the oil filter when you change the oil. A clogged oil filter is one of the most common causes of engine problems, and it usually goes unnoticed.
The oil filter collects the dirt, sludge, and other impurities that enter the oil stream. It prevents these contaminants from clogging the engine, which can cause premature engine failure. Oil filters trap sludge and debris that prevent the engine from being lubricated.
Changing your oil and replacing an oil filter isn’t rocket science, but it can be complicated. It takes a lot of patience and diligence.
Make sure to only install the OEM oil filter as the oil filter should have a certain size and shape. OEM oil filters are designed to install properly and handle the oil pressure in the system. Cheap aftermarket oil filters can damage too early.
When installing a new oil filter, make sure it has only one seal with which the oil filter comes. Look for the oil filter seal being stuck on the engine where the filter goes. If there are two seals, the oil filter would not tighten properly.
Also, make sure to lightly lubricate the seal of the oil filter before installing it. Moreover, if the oil filter is installed too tightly, it will also cause The manufacturer usually recommends certain torque requirements to tighten the oil filter. You should follow them.
6. Damaged or Improperly Fitted Drain Plug Of Oil Pan
If the drain plug of the oil pan is damaged or leaking, the engine won’t start after an oil change. The drain plug of the oil pan creates an air-tight seal so that oil does not leak through it and air bubbles do not form inside the oil pan.
It is generally recommended to replace the drain plug whenever you drain out the old oil as the seal of the drain plug gets damaged due to the oil sludge. It is difficult to find a suitable seal for the drain plug. The metal drain plug has usually a sealing metal washer instead of a rubber seal.
So, I always get a new drain plug whenever I change the oil of my car. Like an oil filter, there are certain torque requirements to tighten a drain plug using a torque wrench. You should follow them.
7. Damaged Fuel Pump
Again, the failure of the fuel pump isn’t related to an oil change procedure in any way. If your car cranks but does not start after replacing oil, the fuel pump of your engine could malfunction.
The fuel pump runs initially to pressurize the fuel line so that the fuel injector can inject the fuel into the engine. The easiest way to see whether your fuel pump is running or not, turn on the ignition key.
As soon as you turn on the ignition key and you hear a hum or whirring noise coming from the back of the car or under your gas tank for a few seconds, it means the fuel pump is running.
Try to take help from someone while you will be doing this. First, check the fuel pump relay and then check the fuel pump. I’ve explained about it in this guide on car sometimes start and sometimes it doesn’t.
8. Damaged Wiring To The Ground or Sensors
In some engines, it becomes trickier to remove the oil filters. You have to go down to the engine bay to use special tools to remove the oil filter.
During the removal process of the oil filter, any wire can damage, which affects the electrical connection of the engine.
So, you have to carefully check that the insulation of any wire, that connects to the engine ground, is not damaged. You can find the ground locations of your engine in your manual.
You should also wirings to different sensors of the engine as the PCM needs readings from different sensors for optimized engine performance.
If you see a check engine light on the dashboard when the engine won’t start after an oil change, use OBD2 scanner tool to find the trouble code related to any sensor. Usually, a crankshaft sensor is located near the oil filter. You should first check its connection.
In summary, cars not starting after an oil change can stem from unrelated issues like a weak battery, bad starter, or fuel pump failure.
However, wrong oil viscosity, overfilling, and improper drain plug or filter installation during the service are common culprits too. Inspecting battery voltage, starter function, oil level and type, plugs and wires is key.
Replacing damaged parts, adjusting oil level, and using proper viscosity oil will get the engine running again. Thorough oil change procedures and checks prevent many no-start conditions.