Car Won’t Start After Changing Oil: Causes, Diagnosis, and Solutions

Changing your car’s oil yourself seems easy enough – drain the old oil, replace the oil filter, pour in new oil. But sometimes after an oil change, your car won’t start. Why does this happen and how can you get your car running again?

Common Causes For Car Not Starting After Oil Change

There are a few common reasons why your car won’t start after an oil change:

• Oil level too low or too high
• Oil pump failure
• Clogged oil filter
• Using incorrect oil viscosity
• Bad car battery
• Forgetting to tighten the oil drain plug

Below we’ll look at each of these common causes in more detail and how to resolve them.

Oil Level Too Low or Too High

Probably the most common reason your car won’t start after an oil change is an incorrect oil level.

• If the oil level is too low, this can cause low oil pressure which will prevent the engine from getting adequate lubrication to run.
• If the oil level is too high, it can sometimes cause issues with oil circulation or foul spark plugs.

To fix an incorrect oil level:

• Check the dipstick to verify the oil level. It should be within the full and add marks.
• If too low, add small amounts of oil, rechecking the dipstick until it’s at the proper level.
• If too high, drain out excess oil until it’s at the right level.

Recheck the dipstick any time you adjust the oil level. Make sure it’s right in the operating range.

Oil Pump Failure

The oil pump circulates oil throughout the engine. If it fails, oil won’t properly flow through the engine which can lead to failure to start.

Signs of a bad oil pump include:

• Low oil pressure warning light
• Knocking or clattering noise from the engine
• Oil level remaining correct but oil light coming on

Replacing a bad oil pump will require removing the oil pan and likely other disassembly. In some cases, the engine may need to be removed from the car to access and replace the pump.

If oil pump failure occurs immediately after an oil change, it’s possible something was installed incorrectly or an oil passage got blocked. Checking for any kinks in hoses or obstructions after an oil pump replacement would be wise.

Clogged Oil Filter

The oil filter cleans contaminants from the oil. A blocked or clogged filter can restrict oil flow which can prevent your car from starting.

Signs of a clogged oil filter:

• Low oil pressure
• No oil on the dipstick even though oil was added
• Oil light coming on

To fix, replace the oil filter with a new one. Use quality filters and change them at regular intervals. Also, make sure the filter gasket comes off with the old filter rather than getting stuck and blocking oil flow.

Incorrect Oil Viscosity

Using the wrong weight of oil can potentially lead to a no-start condition after an oil change.

• Oil that is too thick or heavy (high viscosity) may not flow correctly through the engine causing low oil pressure.
• Oil that is too thin (low viscosity) can leak past seals and may not properly lubricate the engine.

To fix incorrect oil viscosity:

• Consult your owner’s manual to determine the proper viscosity grade for your car and engine. Common ratings are 5W-20, 5W-30, 10W-30 etc.
• Drain all of the incorrect oil out and refill with the proper viscosity.
• Check level on dipstick and top off as needed.

Bad Car Battery

Some vehicles have oil life monitoring systems that need to be reset after an oil change. If the battery was disconnected or died during the oil change, the system may not reset properly. This can prevent the car from starting.

Connecting a new battery or jump starting the car can allow the computer to reset and the car should start normally.

Make sure the battery connections are clean and tight. Clean any corrosion with a wire brush. Be sure to properly dispose of the old battery if replacing.

Forgetting to Tighten Oil Drain Plug

Forgetting to replace the oil drain plug after changing the oil is an easy mistake. This will lead to all the new oil draining out and prevent the engine from starting.

To fix a loose or missing drain plug:

• Raise the vehicle safely with jacks.
• Clean any debris from the drain hole.
• Install a new crush washer on the plug.
• Tighten plug to factory torque specs.
• Refill engine oil to proper level.

Double check the tightness of the drain plug as a loose plug can vibrate out, especially if overtightened initially. Always use a new crush washer to get a tight seal.

How to Diagnose Car Won’t Start After Oil Change

If your car won’t start after an oil change, there are steps you can take to diagnose the specific cause:

• Check oil level and quality. Use the dipstick to ensure oil level is correct and appears normal. If extremely low, add oil. If oil looks foamy or milky, it could be contaminated with coolant or water.
• Inspect for leaks. Look under the car for any puddles or dripping oil that could indicate a leak. Specifically check around drain plug, filter, and gaskets. Tighten fittings or replace damaged gaskets as needed.
• Check for oil pressure. Turn the key to the on position (don’t start) and look for the oil light to come on then go off. If light stays on, low oil pressure is likely preventing starting.
• Listen for odd noises. Have a helper crank the car while you listen near the engine. Clicking or grinding noises can indicate problems like low oil or pump failure.
• Check fault codes. Use an OBD2 scanner to pull engine fault codes. Codes pointing to oil pressure or flow can help identify issues.
• Test battery and connections. Check battery voltage. Jump start the car or charge/replace battery as needed. Clean any dirty connections.
• Check oil pump operation. If oil pressure seems low, verify pump is working properly and has not failed. Check hoses for clogs or leaks.

Thoroughly inspecting the lubrication system prior to restarting the engine can help prevent further damage. Identify and address the specific issue rather than cranking the starter excessively on an engine with oil problems.

Tips to Prevent Car Not Starting After Oil Change

A few simple tips can help prevent the problem of a car not starting after DIY oil change:

• Use a high quality oil filter. Don’t use cheap equivalent filters that may shed debris or collapse under pressure. Stick with the recommended brand and part number.
• Inspect oil drain plug. Check for rounded edges or stripped threads that make the plug hard to tighten properly. Replace if necessary to avoid leaks.
• Check torque on plug. Use a torque wrench to tighten drain plug to factory specification. Overtightening can damage the pan threads.
• Allow oil to fully drain. Let engine cool off completely to allow thick oil to fully flow out of drain hole and oil filter before removal.
• Double check oil level. Check dipstick twice after refilling oil. It’s easy to misread level or forget to top off as needed.
• Reset maintenance light. Don’t forget to reset the oil life percentage monitor after oil change. This will schedule the next change correctly.
• Inspect rubber hoses. Look for cracked or mushroomed oil hoses that may be failing. Replace any worn sections that could collapse and restrict oil flow.

Carefully following the vehicle’s maintenance schedule and procedure can help reduce the chances of no start conditions after an DIY oil change. Patience pays off to make sure the job is done right!

What to Do If Car Won’t Start After Oil Change

So you finished up an oil change, now the car won’t start. What should you do? Follow these steps:

1. Don’t crank the starter excessively. This can grind down the starter motor and battery without pumping oil.
2. Check oil level. Verify on dipstick that oil reading is within operating range, not empty or overfilled.
3. Check for leaks. Look under oil drain plug and filter area. Tighten or reseal as needed.
4. Check oil pressure light. Turn ignition on (but don’t crank) and see if oil light stays on indicating low or no pressure.
5. Check battery. Jump start battery or charge. Clean any dirty connections.
6. Add right viscosity oil. Make sure you used oil with viscosity recommended by manufacturer (ie 5W-30).
7. Install new oil filter. Debris can clog filter and prevent oil circulation. Use quality brand filter.
8. Call for assistance. If problem persists after trying these steps, call for help from an auto repair shop or tow truck.
9. Do not keep cranking engine. This can cause extensive damage. Identify and repair issue before trying to start again.

With some basic troubleshooting, you can often get to the bottom of car no start after DIY oil change. If not, have a professional look at it before cranking starter excessively. Proper oil and filter changes prevent many issues.

FAQ About Car Not Starting After Oil Change

Here are answers to some frequently asked questions about dealing with a car that won’t start after an oil change:

How do I know if oil level is correct after oil change?

Use the dipstick to check oil level. Wipe it off first, then reinsert fully and pull back out to read level. Level should be within the full and add marks on dipstick.

What type of oil should I use for oil change?

Check your owner’s manual for the specific viscosity grade recommended by your car manufacturer such as 0W-20, 5W-30 or 10W-30. Don’t switch viscosity without verifying correct type.

Why does oil light stay on after oil change?

This likely indicates an oil circulation problem such as pump failure or clogged filter or oil passages. Do not keep running starter with oil light on or engine damage can occur.

How do I add oil if level too low after oil change?

Add oil slowly, rechecking with dipstick frequently. Just 1/4 to 1/2 quart at a time until within proper range. Don’t overfill which can cause issues.

What happens if you forget to put oil after oil change?

The engine will run briefly but shut down quickly as soon as oil pressure drops. Immediately turn ignition off to prevent engine damage if started with no oil.

Can wrong oil filter cause car not to start?

Yes, wrong filter size or using low quality filter can affect oil flow and pressure. Use filter recommended for your specific engine. Beware cheap generic filters.

Why does car crank but not start after oil change?

If engine cranks over but won’t start, oil isn’t the issue. More likely spark or fuel system problems. Check for codes pointing to crank/cam sensors, ignition components, fuel pump etc.

Conclusion

Changing your own oil seems straightforward, but many things can cause an engine to not start afterward. With some basic troubleshooting, you can identify and correct common issues like:

• Incorrect oil level
• Clogged filter
• Oil pump failure
• Wrong viscosity oil
• Loose drain plug
• Dead battery

Pay close attention during the oil change process to prevent problems. Allow proper drain and refill time, double check oil level, and reset any required maintenance lights. Your car should then start right up with fresh, clean oil protecting the engine.