Letting the oil life monitor down to 8% is not very good for any engine. Most manufactuers recommend only letting it go down to 20%. I have done this with all my cars and never had an issue with the engine. My old 2006 Saab 9-3 I owned until 190,000 miles and then sold it when a tree fell on it. My mechanic bought it from me for scrap, but then fixed it and sold it to another customer who still drives it today - with 250,000 on the powertrain. I currenly own a 2013 Subaru Legacy that now has 127,000 on it. Again no problems and I change the oil religiously every 5000 miles.
There are a variety of reasons for your engine oil smells burnt, including:
While it's important to have the required amount of oil around your engine, this oil must flow within certain flow paths. If the oil left these flow paths, you would be dealing with your engine running on low oil, which is very dangerous.
There are many reasons for the oil to leave its appropriate paths and leak internally. Some of these leaks could be very small, while others might be very big and significant.
For example, if you looked under your car and saw a puddle of oil, this is a clear indication of a significant oil leak that prevents you from even driving your vehicle.
Unfortunately, this case requires some help from a professional mechanic because small cracks might be hard to detect why any driver who doesn't have the required mechanical skill sets.
If the oil leak is big and you can see it, it's recommended that you never attempt to move your vehicle before consulting a professional mechanic. If your vehicle is running in very low oil, the problem could be very serious and could damage your engine immediately.
All leaks must be taken care of to continue driving this vehicle. This could be by changing or removing the bad parts. After the professional mechanic test leaks' locations, he can remove the cracked pipes or the components that are causing the leak.
There is no fixed price for how much it costs to repair internal oil leak because it depends heavily on the amount of cracks and the location causing the leak.
Your head gasket is a small component sitting on top of the cylinders to prevent any liquid's from making its way inside the cylinder during combustion.
If any liquid got to this part, you affect the air-fuel ratio, and therefore, the combustion process will produce weird smells and strange gases.
One of the common causes for your engine oil smells burnt a blown head gasket. The head gasket will not be able to do its job, and a lot of oil could make its way inside the cylinders and get burnt. To confirm the problem, you could monitor the smoke that is coming out of the tailpipe. In paragraph usually, if too much oil is getting burnt inside the cylinders due to blown head gaskets, you will see weird blue smoke coming out of the tailpipe.
Any excess oil during the combustion process is stored and blocked by a certain valve around the engine. This valve does not allow a lot of this oil to get into the combustion system and causes the engine oil burnt smell.
If this valve gets damaged for any reason, your engine oil smells burnt. To resolve this problem, you need to change the valve.
Luckily, replacing a valve does not require many costs and usually can be done by the driver because it doesn't need a high level of mechanical skill sets.
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Oil spills after an oil change
This is probably not your issue since you said it smelled burnt BEFORE the oil change.
Many people complained that their engine oil smells burn right after an oil change. This is not surprising, especially if you are having your oil change done by a nonprofessional mechanic.
Think about the mechanic when he attempts to pour the oil inside the oil tank of your vehicle. If he drops any little oil around the engine block, this oil can get burnt easily due to the high heat coming out of the engine's block.
This type of oil-burning smell is not very serious because it's small and not related to significant internal vehicle problems.
Therefore, you don't have to panic, and sometimes you don't have to do any action assuming that the oil drops are small.
However, if there was too much oil spelled around the engine's block, it might get so hot and could burn some of the rubber components around the engine.
Bottom line, it's better to check with the mechanic and inform him what you're dealing with. Unless you know what you are doing any of these four options could be what is causing the smell. Just hope it is not the first two as those are the expensive reasons. Best of luck!