San Carlos Auto Repair

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How often should I change my oil?

Question posted by Lynn K. regarding her Toyota Prius

"I am writing into your mechanics blog for an answer on how frequently I should change my motor oil in my vehicle?"

How often should I change my engine oil?

Lynn, thank you for the question!  On average the vehicles we work on at A+ Japanese Auto Repair are due for an engine oil and oil filter change every 5,000 miles or 6 months (whichever comes first).  As a rule of thumb…  If you are an extremely low-mileage driver you should change your engine oil and oil filter at least once a year.

How does my cars computer know when an oil change is needed?

If you drive a newer model, such as your Toyota Prius, the car may display when you need to change your oil and oil filter on the instrument cluster or dash display.  This system is typically referred to as the Oil Life Monitoring System.  If you are lucky enough to have this reminder system built into the vehicle it sure makes life easy!  If not, the best advice I can give you is to check with your owner’s manual.    The Oil Life Monitoring system is actually more complex then the vehicle turning a light on at a specified mileage.  Oil Life Monitoring Systems tell drivers when their car actually needs its engine oil change, based on  the following criteria and driving conditions:

  • Driving habits
  • Cold starts
  • Extensive idling and/or stop and go driving
  • Short distance trips
  • The climate in which the vehicle is operated

At A+ Japanese Auto Repair we currently see these systems in Honda, Acura, Lexus, some Toyotas, Mini, and many other vehicles coming out this model year. 

What Happens if you Don't Change Oil in Your Car?

If you do not change your engine oil.  You will have serious issues!  As Alina Tugend of the New York Times says, "It just gets dirtier and dirtier. It’s like mopping the floor with a bucket of water and detergent. The water starts out clean, but the more you use it, the filthier it gets. Eventually, you’re making the floor dirtier if you don’t change the water."

Here is a great visual comparison of dirty engine oil vs. clean engine oil:

The above analogy is great!  So what are the major concerns with dirty engine oil and oil filters and prolonged engine oil change intervals?

  • Reduced engine life
  • Lack of performance
  • Contamination (dirt/water/other fluids etc.. causing internal engine wear due to lack of lubrication)
  • Reduced detection of issues (If your vehicle is not being seen regularly issues cannot be caught before they turn into major issues

To sum it up:

 A+ Japanese Auto Repair recommends you follow your owners manual for the best recommendations on your specific oil change intervals and fluid types that should be used.  If you have any questions feel free to contact us!  Thank you Lynn for the great question!  If you would like to dive a little further into our engine oil change information please visit our engine oil change information page on our website:  Engine Oil & Filter Service Page

Written by Eric Sevim - ASE Master Certified Auto Repair Technician

A+ Japanese Auto Repair, Inc.

780 Industrial Road

San Carlos CA 94070



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