92,000 miles. Got an oil change, the next day the oil pressure light started coming on at idle. Mechanic changed the oil pressure sensor, oil light still flickering at idle. Took car to dealer for another oil change thinking I may have just gotten a bad filter or the wrong grade of oil. Light still flickers at idle. Car makes no noise, engine runs smooth. Took car back to mechanic and they put in a new oil pump. The next day, oil pressure light stayed off on my way to work (45 miles) but came back on at idle on my way home. No knocks, no engine noise. Took back to mechanic, he drove around and couldn't get light to come back on. He didn't have an answer. Light didn't come on at all yesterday, but today came on at idle after driving about 5 miles, but when I got to work (40 miles) the light didn't come on at idle. Is this just an anomaly? Or maybe a short somewhere? It was coming on consistently at idle before the oil pump was replaced, but only sporadically now. Car has had regular oil changes and this oil light flickering started after my last oil change. Any ideas?
I would also check for a wiring fault on the oil pressure sensor wiring as it might be as simple as that. If a wire has rubbed on something and is intermittently touching an earth, it will cause the oil light to flash on and off. Given all the things you have already done, this does seem likely. I once had a brand new oil pressure switch fail after a very short period and gave the same symptoms that you are getting. Another new one fixed the problem.
1. As a basic measure I would make sure the correct grade and spec oil is going in the engine. You can no longer trust that a local mechanic or even a dealer service center will necessarily use the required product as stipulated by the manufacturer. It is always better to buy and supply your own so you know the correct product is being used.
2. I would not assume there is a problem with the oil pressure warning light even though there could be.
The first thing the mechanic should have done when you reported the oil pressure issue is to hook up an independent mechanical oil pressure gauge and check oil pressure when the engine is hot at different RPMs. Any oil pressure issue will usually show up at idle when the engine has been warmed up properly and the engine oil is hot (unless you have some kind of intermittent oil pressure relief valve that is sticking). Just replacing parts without actually knowing what the oil pressures are at different RPMs is being sloppy and negligent.
This is what you need to do now. Contact a business that can hook up their own pressure gauge to your engine and have them check the oil pressure readings at various RPMs when the engine is fully warm. If there is a low oil pressure issue it will show up on the oil pressure gauge. As you have a new oil pump there should be no issue now with oil volume or a sticking oil pressure relief valve which on your engine should be part of the oil pump assembly.
3. Worn engines will not be able to sustain required oil pressures. Oil pressure is not produced by the oil pump. The oil pump produces oil flow but the resistance to flow is what produces the oil pressure and that resistance is created by fine clearances between operating engine parts especially on the crankshaft and components connected to it. Once the engine wears the clearances increase and the oil flows past the parts much more easily and produces/builds much less pressure.
How well your engine with over 90000 miles has been maintained depends on how often all the owners changed the engine oil and filter , whether they kept the engine oil level up to full (most owners rarely ever check oil levels between services) and whether they always used the correct product. Manufacturer oil change intervals shown in service schedules can be 10000, 12000 miles or more which is much too infrequent for the type of use 95% of private vehicles experience which typically are on the severe to very severe use end of the spectrum. Engine oil typically needs to be changed at least at half the mileage shown in service books (at least twice as frequently) and thus at least every 5000 miles if you want your engine to last.
Thank you, going back to mechanic tomorrow to get an oil pressure test. I'll have them put back in 5W20 because I'm pretty sure they used 5W30 this time and the quick lube place used 5W20 last time. The mechanic said the lighter oil would cause less pressure, so I can't figure out why the heavier oil would cause a low pressure issue, but I'm no expert.
Do you know what rpm my car should idle at? When I first start it and drive a couple minutes, it idles between the 0.5 and 1, but after driving a while, it idles right at 0.5 or below, and that is when the low oil pressure light comes on.
1. If the manufacturer specifies a 5w-20 oil then only use that viscosity. There are various 5w-20 formulations for different engines as there are in 5w-30. Make sure you select the one formulated for your engine. The info is on the label on the back of the container.
There is not a huge difference between the 5w-20 and 5w-30 and testing them side by side you would need a good oil pressure gauge to see much difference in oil pressure on the same engine at operating temp.
You are best to use a fully synthetic 5w-20 oil in that engine. They are much more expensive oils though.
I would stay away from those quick lube places as you could never trust them to use the correct product even if they say they have done so in the documentation they give you.
2. When the engine is cold the computer runs the idle speed higher, usually up to around 800 rpm or so. Then it drops it back to normal idle speed. Depending on the program and engine temp that can take from about 30 seconds to more than a minute. What you have described is normal for your car. If there is an oil pressure issue with the engine this can typically show up at normal idle speed when the oil is hot.
3. You won't know if there is an oil pressure issue until an independent gauge is fitted to the engine and the readings are checked with hot oil at various rpms. There may be no issue at all other than the electronic sender unit being inaccurate on your car. If there is an issue I suspect it might be due to engine wear such that the engine can no longer sustain normal oil pressure at all rpms because of the wider clearances between moving parts. I would however drop the sump on the engine and check the oil pick up and screen to ensure there is nothing (such as oily sludge) retarding oil flow from the sump to the oil pump although that should have been checked if a new oil pump was fitted to your engine.
Wow, thank you; you are very helpful! Taking these notes with me to the mechanic.
So they did do an oil pressure test. Pressure is good at high rpm, but drops to 8 at idle and apparently the sensor is set to go off at 10. They rechecked everything else and said sender was good and pump was good and that everything points to a worn engine from neglect from previous owner. He recommended putting in a heavier oil, but told me I can probably get another 100,000 miles, but if I got a good deal on a trade in go for it. So not great news, especially since the car fax report showed regular maintenance.
Hello again Kelly. Interesting update. Here are a few thoughts.
1. I would have expected to see oil pressure at higher rpms at less than normal with hot oil but certainly not low enough to trigger a warning.
2. With the symptoms you have now which is just low pressure at idle or low rpm with hot oil, I would definitely look to see if you have any engine oil leaks. Sorry I should have raised this before but you never mentioned any leaks. If significant enough this can certainly cause a drop in pressure. One area to look at is around the oil filter housing connection. Some owners have also had the oil pressure sender/switch leak where it screws into its fitting(I presume the seal fails) and trigger the oil warning light.
http://www.rockauto.com/en/moreinfo.php?...
The leaking oil builds up in the engine valley section and then eventually runs out. But yours has been replaced with a new unit you mentioned and as long as it is not leaking now it will be fine. It is buried under the intake manifold (taking some time and work to get to - bad idea) so you cannot see it and if oil is leaking from there you cannot see it until eventually it runs to the outside of the engine and to the floor and you know you have a leak somewhere.
So if you have any oil leaks I would have a close look at those before giving up on the engine. ( Oil can leak under pressure internally as well usually escaping via a failed head gasket into the cooling system . In this event you will have to top up your oil and if you check the radiator coolant with the engine cold you would see evidence of oil in the coolant. I doubt you have this issue but check the radiator coolant when the engine is cold just to be sure).
2. It is your choice but I would not try and solve/disguise the
problem but putting a heavier viscosity oil in the engine. Hyundai specify a 5w-20 oil for good reason one of which is to get the oil flowing from the oil pump to the top end of the engine which is just as important to lubricate as the bottom end.. If you put a significantly heavier oil in you will likely cause a problem with lack of optimum lubrication to the top end of the engine. This will likely manifest itself in a noisy top end with metal to metal contact which proper lubrication avoids. These modern engines are very sensitive to oil viscosity and the Hyundai engineers, together with the lubrication engineers, go to a great deal of work to come up with the optimum oil viscosity for the engines, and lubrication systems in those engines, they design.
3. Hyundai oil and filter change schedule for these engines in "normal use (which is code for "optimum" which very few owners experience) is specified at every 7500 miles. Still too long but this is what most owners will run to or even longer before they get around to it. In severe use which most owners experience, Hyundai specify a more frequent interval, every 3750 miles, and few owners will do this because often this is buried in the fine print and most people never read it. AS you can see an enormous difference in mileage and it makes a big difference to engine wear especially if you do not use a fully synthetic oil.
https://www.hyundaiusa.com/maintenance-s...
The problem also when buying a used car, you don't know if a previous owner has let the oil run very low, which may be due purely to a neglected oil leak or other causes, (people do this all the time because they don't do regular checks) and once that happens you will get excessive engine wear.
In that event the engine will eventually be unable to sustain normal oil pressure.
Cheers and all the best,
S
Hi Sean!
I will keep using the 5W-20 as recommended as reading what you said, it could be worse using a heavier oil. Thank you for the information.
99% of my driving is highway miles. I drive about 5 city miles (a couple red lights) and then go 35 miles on the highway at 70-80mph. Since this issue is only happening at the lower rpms and the pressure is good at higher rpms, I don't feel as worried and basically plan to drive until the engine goes. (Hopefully not for a long-time :))
The oil pressure warning light is very wonky. This am, it was 33 degrees F, I drove the 5 city miles to get on the interstate and the light came on at the first stop light. Engine was obviously still very cold. Was at the light about a minute and no noises or shakes. After driving 35 miles on the highway, the oil light did not come on at any of the 3 red lights I hit.
I have had this issue for a month now (first appearing the day after the oil change) and I haven't seen any oil spots on my driveway and I have been checking the oil level every fill-up to be sure I'm not losing oil. The level is full and the oil looks very clean.
I am the 3rd owner so you are right, the engine may have been abused. The first owner put 36,000 miles on it in 2 years and kept meticulous records (written in the user manual) The car was sold Hyundai Certified Pre-owned. All I can tell from the second owner was that they put on new tires and had recently had an oil change because the sticker on the windshield showed it was due for a change in about 1500 more miles. The 2nd owner put about 36,000 miles on the engine in 2.5 years, so I assumed it was highway miles, but you are right, I don't know if they kept the oil level at full or not.
I will check the radiator coolant to see if by chance there is any oil in it.
Car runs great though, smooth, quiet, no loud noises. When I picked it up this last time from the mechanic there was a heads up penny on the seat so I'm hoping that brings luck, lol.
Thank you for all your help. It's great getting advice from someone so knowledgeable about this car!
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