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“Oil life %” readout — when to change?

I use the “Oil Life” % display to help me prepare for a change. What is it measuring and what’s a safe level to let it go to?

First of all lets assume that you actually do a check of the real oil level on a regular basis . Like once a week . Second look in your manual and see if it says xxx miles or xxx months to change the oil . I would never go past 7000 miles or 12 months no matter what the percentage readout was.

Many wait until the change oil soon message comes up, while I prefer to change earlier, around the 20% mark. I second what Volvo_70 stated , though I drive more than that so it is not an issue.

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Good rule, 10-20% left is a good rule .

The car mfrs use an algorithm that quantifies diverse factors including–but possibly not limited to–odometer mileage, elapsed time, the number of cold starts, and how many short drives you take, in order to come-up with the electronic alerts that you see.

That being said, you need to change your oil at least once per year, no matter how few miles were driven, and I wouldn’t go more than 6 months before changing my oil.


I start thinking about it at 20% and it is changed by 10%. I did that on our old van, and after 185,000 miles, the engine was still running well and not burning oil. My daughter runs it down to zero sometimes in her 2012 Cruze, and it’s running fine. It’s reliable enough that they use if for cross-country vacations.

Your owners manual will tell you what it’s measuring, and more importantly, that it’s up to you to check the dipstick and make sure there’s enough oil, whatever its age.

We’ve had this discussion before but I change mine at about 50%. That’s 5000 miles on the Acura and 3000 on the Pontiac. An extra oil change a year costs me $30 for synthetic and about $20 for dino for the Pontiac. I had the discussion with the Acura Service Manager that was telling me what they went through to come up with the computer program. Good for them but it’s my car and if I want to waste and extra $30 a year on a $45,000 car, so be it.

I don’t have a readout, only a light that comes on when the computer perceives it is time to change the oil. I have gone up to 7k, but never seen the light, I do oil in spring and fall, no matter what the mileage, sure I only have 198k on the car, and sure I need a quart every 3k miles between changes, but better to often than not often enough.

I would expect that 100% represents the life of the oil with a margin of error included, if you the manufacture wanted you to change the oil at 50% or 80% then the oil life monitor is flawed.