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Oil weight matter?

after changing the oil in my sons 2004 neon

i noticed on the oil cap it says to use 5w-30 and i used 10w-30. am i in trouble?

No it won’t cause trouble really. But in the future 5w-30 really should be used, especially in the winter months.

Depends on how cold it gets. I’d rather have a 5 Winter weight oil in the engine than a 10 Winter weight. Afterall, it’s the cold start that wears the engine.


No, you are not in trouble. The owner’s manual probably says both 5W30 and 10W30 are acceptable oils to use. The 5W30 will give you slightly better fuel economy and will perform better in cold climates, but the 10W30 should not have harmed the car. Still, I would switch to 5W30 next time.

Keep in mind the first number (the 5 or the 10) represents the weight (or viscosity) of the oil when it is cold and the second number (30) represents the weight of the oil when it is hot. So both oils have the same viscosity when the engine is warm.

Check the manual, likely not a problem - where do you live?

The comments from others are all right on the money.

Although you are probably fine with this oil in this car, I would just add that modern cars use oil as a coolant as well as a lubricant, so using oil that is a greater viscosity than recommended will void the warranty. A friend was once called to give expert testimony in a lawsuit against Mazda for voiding a warranty due to wrong oil viscosity being used. Mazda won the case.

No trouble, but next time you change the oil use 5W-30.