Wow, that's very cheap. Wet sump, I assume?

 

The oil has not gone bad after 900 miles.

No way.

But, change it every 3000 miles...cheap insurance...




A friend of a friend might just reset the oil life monitor and vow to drive more than 900 miles in the ensuing year.

 

5w-30 on sale maybe. Big jugs

 

I ordered a sample kit yesterday. I will be changing oil this weekend so let's see if the oil life algorithm is right before we go further

 

yes, wet sump
but dry would of only been 2 -3 qts more

 

I just purchased a 2014 Corvette and the oil looked perfectly clean however it hadn't been changed for about a year or longer. I changed it within a couple days to keep my mind at peace. Oil is cheap and new engines are expensive.

 

When I buy a used car, I have a simple rule. It flows, it goes. I don't even bother to look and guess. Not that I can see oxidation.

 

I see oil at $23-26/gallon is why I ask.

 

oh yes…. I definitely prefer the big jugs!

 

I've averaged about 4500 miles a year on my 2017. I've changed the oil 1-2 times a year with no issues

 

Unless you did proper testing, for example, wear characteristics as to whether there was accelerated or decelerated or no change in wear, "no issues" is worthless at best, misleading at worst.

 

Not sure where you are seeing oil that high, but that is .

I have always changed my oil once per year as I do not put that many miles on the car. Putting fresh oil in once/year is not that expensive and I know it is properly protected.

 

Walmart 5 qt jugs of Mobil 1 5-30 = ~ $23 - $30.

1 to 2 Qts more to get the oil level correct from another 5 Qt. jug that was saved from last oil change. Always buy two jugs and save the extra for the next couple of oil changes.

PF64 = ~ $5.

So oil change = ~ $35 - $40.

Oil and filters are cheap and really don't care even if they were 2x the cost. I'm doing it myself the right way.

 

I think you might be missing one part about the PCV. The pistons create the positive pressure, that is then vented to the intake of the engine. In ye olden days the crankcase pressure was vented to atmosphere, but for emissions it is routed to the inlet of engine to be passed through the combustion chamber and exhaust. A PCV system doesn't intake clean air, it is exhausting crankcase pressure (mixture of previously combusted air charge and oil vapor) from out of the crankcase.

 

Well I change my oil each Spring. I use Amsoil, which is a better oil IMO. I put on about 5000 miles each year.

I pay about $12/quart, and buy 10 for my dry sump. I also use their filter which is expensive too, at more than $15 if I remember correctly.

So it breaks down $120 for oil and $20 for filter for a total of $130-140 and I change it at home.

I think that is about what folks pay at the dealership for Mobile 1.

Ken

 

I would add time and labor into the equation. My time to go to the Amsoil dealer and do the job and clean up and dispose of the oil.

 

Your post is correct up until the last sentence. True, in the bad old days, piston blowby was routed to the atmosphere. Also true, with PCV it is routed to the engine intake. But your statement that PCV doesn’t intake clean air is incorrect. The PCV system does suck in clean air from downstream of the engine air filter. If it did not, the engine vacuum which the PCV valve sees would create a vacuum in the crankcase, which you do not want. So there is a steady flow of filtered air into the crankcase, sucked in by engine vacuum acting on the PCV valve. The ratio of air to piston blowby gases varies, depending on the condition of the rings and hence the amount of blowby. But with rings in good condition, there is typically more air than blowby gas in the crankcase, except of course for wide open throttle operation, where blowby is at its greatest and there is little or no engine vacuum.

 

you can get 10 quarts of synthetic oil and a filter for $35?

 

I don't think this is true, as there is a check valve aka "PCV Valve" that prevents pulling metered air from the air intake into the engines crankcase. The PCV isn't an intake source for the engine. Crankcase vacuum is highest at open throttle due to the engine drawing air from the PCV. The purpose of the PCV is to create vacuum against the crankcase by using the intake stroke.

https://en.wikipedia.org/wiki/Crankc...stem#PCV_valve


If the PCV valve didn't exist, then yes the crankcase could be pulling in air from another source. But this would toss the AFR's since that's air that was metered via the MAF, but no longer in the intake charge.

 

CPB, the first few sentences of your own reference in post #39 disprove your belief, talking about airflow and a mixture of air and crankcase gases. The PCV valve has two way action which is why it rattles when you shake it. At high vacuum such as idle, the valve body sides to the side of the vacuum, thus limiting airflow when the airflow through the PCV system could otherwise mess up air to fuel ratio at idle. It does not close completely, it simply leaves a very small opening so that flow is small. On the other hand, if pressure in the intake manifold is higher than that of the crankcase such as a backfire, or a super or turbocharged engine at high boost, the valve body slides the other way and can close completely to prevent pressure from being applied to the crankcase. If you don’t believe me, just go look at your engine. Somewhere on a V8, almost always on the bank opposite the PCV valve, there will be a hose that allows air into that rocker cover. That’s the PCV inlet, sometimes called breather. Most of the time, flow in that line goes into the rocker cover and thus crankcase, sweeping the piston bypass into the PCV valve, where the mixture of air and piston blowby gets sucked into the engine by vacuum and gets burned. In those rare cases when the PCV valve slides the other way because intake manifold pressure is higher than crankcase pressure due to backfire, or high boost in a turbo or supercharged engine, flow in that line can be in the other direction. It still gets sucked into the engine, just via the normal intake line rather than the PCV valve. In those cases, the crankcase is indeed pure piston blowby, but as soon as the backfire or high boost passes, flow is the normal air sweeping piston blowby through the PCV valve.