A&Q about 350Z
Q:
The more tightly controlled the combustion is in an engine, the cleaner the oil stays.
This particular engine is a ULEV lean burn engine which I'm sure never runs any richer than it has to to keep exhaust temps in check.
It's going to run much cleaner and much longer (inside and exhaust) than something with a carburettor.
A:
If you use a high quality filter, it's only very small particles that the filter won't be able to filter out. But that's why there are dispergents in the engine oil. The dispergents makes sure the dirt, mainly soot from the combustion don't agglomerate.
But usually you can't judge by looking on the oil how long it can be used. The limitation on how long the oil can be used is mainly dependant on the breakdown of additives.
After the additives have broken down the oil will get bad quick, the oil won't be able to neutralize acids, it won't be able to protect the oil against oxidation, if won't be able to prevent metal-metal contact when the oil film breaks down and so on.
A:
I've heard all the good stuff about synthetic oil and wanted to start using them, but I read on another site that you can't just switch from regular to synthetic on a whim. It says to flush all the natural oil with a flushing oil. If you guys could clear this up it would be great because I want to switch to synthetic in my 2 cars because of the benefits and I won't have to change oil every 3 months.
FYI my accord has 160k and the other has 130k. Too late for sythetic in these cars?
A:
very true.
i guess i'm just used to the NASTY oil that comes out of my car after only 3K miles. it is black as tar, smells like gas, and has a slightly sulfurous smell to it.
i really should try to fix that...
A:
It's never too late, but this late in the engine's life, switching to synthetic would make any oil leaks (and they ARE there) MUCH more apparent.
A:
Thanks Steel, maybe i'll just stick with dino oil until the I either rebuild the engine or get a car with lower miles.
A:
You can easily switch from a mineral oil to a synthetic whenever you want. Just make sure to use a synthetic oil that suits you engine, for the best effect, make sure that it's a real synthetic oil you get and not a highly refined and hydrocracked mineral oil as those are commonly sold as "synthetic".
This was a common problem for early synthetics, today it's not a problem.
Early synthetics where more or less pure PAO and PAO as no swelling effect on seals. Today synthetic oils contain a part of synthetic esters and these have a swelling effect on seals, so leaks isn's a problem anymore. At least not a bigger problem than for mineral oils.
Esters are also friction modifiers so they produce protective films om parts where lubrication is poor, such as as the valvetrain. This reduces friction as well as wear.