Hello ALEX STATHAS,
So, your close the PCV Valve is located on the passenger's side of valve cover I have included a photo for you. Under normal driving conditions you were correct, air does go from the intake to the valve cover and exit through the PCV Valve on the passenger's side of the valve cover and travels back to the intake via another hose. However, when under heavy load conditions such as wide-open throttle sometimes referred to as WOT, gasses are sucked into the intake using both hoses.
For the oil changes. Nissan recommends every 5,000 miles so doing it sooner is really good for your engine. It keeps it clean and running at its best. I have an Altima myself I change the oil every 3,000 miles or 3 months as well. To me 5,000 miles is too much. I have seen Ford's that the oil gets changed every 10,000 miles. To me I don't see how this is a good idea.
The PCV System relives crankcase pressure. Without it, it will cause oil leaks by pushing out seals and gaskets. It also can increase oil consumption by allowing oil to enter the engine and be burned. This can lead to performance and fuel economy issues. It can also cause sludge to build up on the valves and pistons, put stress on bearings and build oil up in cylinders causing a misfire. So, it can cause an issue and it is possible it could seize up the motor, eventually but more indirectly.
As for when to replace it, Nissan isn't giving me a certain interval and most manufacturers don't. To be honest with you doing early oil changes you probably won't have to ever change it. I would check it every 4 oil changes myself. I just take it out and shake it. If you can hear it rattle, then it is good if not it needs to be replaced.
I will say this though, this part is under or around $10. If it goes overlooked and clogs it can cause costly repairs and irreversible engine damage. So, if you want to replace it at a certain interval like say every 15-20k miles or maybe every 6 oil changes it's a small price to pay to keep your engine running at its best. Definitely a part that shouldn't be overlooked.
Engine replacement cost can vary widely depending on your location and the shop that does the work. It also depends on how many miles are on the used engine and its condition. Used Nissan versa engines are selling for anywhere between $400 and $2200. Then the shop will mark it up and replace on time parts like gaskets as well as replacing some hardware, coolant, oil etc. Then it also depends on the shops hourly rate some are over $100/hr others are closer to $70/hr at say about 8 hrs or more. If it's done at a dealership, I would say around $4,000 and a local shop would be probably closer to $2,000 but it depends on what they pay for the engine.
As for Walmart refusing to change your oil because of engine noise it's possible but I do not know their policies. But it's a possibility due to liability issues. Also no one can force you to go anywhere you don't want to and I can't imagine a place refusing a job. If you under the service interval but you're paying, then I don't see why they would refuse the work. Unless you have some kind of aftermarket service program that is paying for the work being done then it is at the discretion of the service company. I personally would find a good Nissan dealer and go there. Nissan service advisors have a score called KPI. I forget what it stands for, but these advisors work hard to make you happy their job depends on it and if there is an issue, they will make sure it's fixed or it's on them. Nissan uses this to see how dealerships are performing and the owner and service manager hold them accountable. Plus, you get the OE filter which I definitely suggest as all filters are not made the same way.
I hope all this information is helpful. Please let me know if I can clarify anything or help any further.
Thank you,
Brendon
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Saturday, April 8th, 2023 AT 8:07 AM
