Mazda 5; 0w-30 instead of 0w-20?


I was changing the oil in Mazda 5 this morning and noticed, as I was pouring it in, that I bought 0w-30 instead of 0w-20 which is called for in the owner’s manual.

Should I drain it and put in the specified oil weight or is it close enough?



You car will do just fine with 0w-30. It is just slightly thicker at operating temperature than 0w-20.
If you were to look in the Owner’s Manual for this car with the same engine sold in other countries you’d find that a range of oil weights (another description of thickness or viscosity) are acceptable, depending on ambient temperature.
In the US, car makers are driven to recommend the thinnest oil that can give acceptable protection against wear, not optimal protection.
Why? Because of government mandates to increase fuel economy.
Engines turn more freely with thinner oil.
You might get a fraction of one fewer MPG with the 0w-30 oil, hardly worth the trouble of another oil change.

To those that claim the engine may not work properly with the slightly thicker oil, I ask how does the engine withstand a cold start when 0w-20 oil at 70F is thicker than 20w-50 oil at 180F?


Maybe. If the engine has variable valve timing, that can make the oil spec more critical than it would otherwise be. If there’s trouble with a VVT system, the first questions should be about the quantity and qualities of the oil.

Another reason to prefer the 0W20 over the 0W30 is its narrower range. That means more lubricity and less viscosity enhancer. Is that a meaningful difference? I don’t know.

How many times in the next six months will you worry about the characteristics of your oil?

1 Like

Can you detect a vvt issue when using wrong oil weight?

Correct…and at operating temps the 0W-30 is still thinner then 0W-20 when it’s cold.

I actually switched to 0W-30 from 0W-20 on my highlander over a year go. My wife’s 07 Lexus (with same engine as my 14 Highlander) oil recommendation is 5W-30. I switched it over to 0W-30 also. That way I only need to buy one type of oil.

1 Like

Different weight oil can be used when outside the jurisdiction of the EPA, this is from the 2015 Mazda owners manual;

Use SAE 0W-20 engine oil. If SAE 0W-20 engine oil is not available, use SAE 5W-20, 5W-30 engine oil”

Heavier engine oil is not going to harm the VVT system.