My sister in law lives nearby. Her husband does not live with her (long story). I try to look after her sometimes.
Recently I asked about her older Toyota Avalon and if she checks the oil stick between oil changes. The car leaks a bit of oil and she does have some quart oil containers in her garage if she needs to add some oil to the engine. The thing is that she says she just waits for the oil light to come on before adding oil. She doesn’t want to get her hands dirty. She promises me that as soon as she sees even a flicker of the oil light, she adds a quart.
Is this a good idea? If one waits for the oil light before adding oil, has some damage already been done to the engine?
It’s not the best idea, but presumably the sensor is there to tell you your oil pressure is low.
I’ve had to top up my oil three or four times because the oil light came on. I have 400,000 Kms on the car and the engine is the least of my worries right now: brakes and suspension are starting to go.
some cars do have oil level sensors (e.g. some German marques) but for most vehicles the oil warning light means the oil pressure has dropped to zero at the switch. The oil pressure switch is a normally-closed 12 volt switch plumbed into the oil galley, usually near the pump. when the oil pump builds pressure, the switch opens and the light turns off. if the oil level is low enough, the pump may “suck air” when the oil in the sump sloshes away from the pickup, and the pressure switch will close and the light will come on.
now, a brief momentary interruption in oil flow may not be catastrophic, but it is a very, very unwise way to gauge when to add oil. Suppose the oil pressure switch fails or the warning light burns out?
The oil light is not an oil level light - if it comes on, your oil level has been way too low for a long time. It also means that you are over-taxing the lubrication properties of the oil (1-2 quarts doing the work of four or five).
The oil light is not a low oil warning like a low fuel warning. The oil light is saying “well, your engine is running dry now and you’re grinding it apart”
Having the oil light come on is an emergency. To prevent further damage to your engine you should immediately pull to the side of the road, leave the car there, and return with oil. If there’s a source of oil very close, you could risk it at the cost of potential damage getting to it.
Something else is wrong with her car if she’s having to replace the oil regularly like that, but even so, the oil light coming on means it has been running below an adequate amount of oil for a long time. It’s bad all around.
Solve the issue that’s causing the oil levels to drop. If not, at least regularly top it off so you never reach even halfway empty, let alone running dry.
If it comes on and stays on with no prior flicker, then I’d say “pull over, your engine will die in a few minutes if you continue to drive”
But I have had cars that leaked/burned oil that were never going to live long prosperous lives anyway, and occasionally the way I remembered to put oil in was because the oil light would flicker on and off during a sharp curve or heavy braking.
Sure, it’s not the intended use of the light, but it did the job and those cars served me several years.
You can get away with it if you only do short trips on urban roads. If the oil light comes on when you are doing 70 on a motorway and the next service station is 20 miles away - you have a problem.
This is what happened to my daughter. She normally drove 5 miles to work and back every day and topped the oil up when the light came on. One Friday evening she set off to visit us, 120 miles away. The engine seized after about 30 miles, leaving her stranded on the hard shoulder in the middle of nowhere. She had to be rescued by the RAC and the car was scrap.
Yes. The engine is already being damaged. I was told this by a mechanic after my oil light came on only a couple of miles from a garage on a road trip. I assumed it was BS aimed at getting work out of me. On checking with a mechanic I know it turns out to be true. Easier to check nowadays - Brand: Oil warning light often means ‘it’s too late’
Ironically the only two times my oil light have come on while driving having been caused by a fault in the oil pressure switch that allows the light to come on.
I once had a car which had a glitch in the electrical system which would cause the oil light to come on when there was plenty of oil. Problem was, I couldn’t ever assume it was a false alarm; this time it might really be an emergency. So, every time the light came on, I had to go through the whole routine as though it was real.
So what’s the deal with oil status displays in more recent cars? The ones that display a percentage of oil life (I guess). What’s a good percentage to change at?
+1. I’ve had a few clunkers where this would happen, and I was always mindful to top the oil off after that happened. They all lived long lives. Obviously, though, YMWV.
Of course the other flaw in this strategy is that the oil light doesn’t come on until you’re several quarts low. So just adding a quart will keep the car perpetually low on oil which is still bad even if you never run it completely out.
All engines are already getting damaged all the time: they have a designed life, and you need to rebuild or replace after that. Running hot, heavy load, degraded oil, wrong oil, wrong fuel, wrong coolant, all these things decrease the expected life some more than others.
Like others here, I wouldn’t be heartbroken by loss of oil pressure for a couple of flashes in the life of my car. I’d stop and add oil immediately, then get on with my life. In particular, I wouldn’t worry about oil temperature: that’s what the engine temperatue warning is for. But if your car is so old and worn that it is already burning oil, you don’t want it to fail suddenly while you own it, so maybe you ought to baby it a little bit better.
