Synthetic Oil..color..longevity

cadillac
cts

#61

That’s a recommendation I support.


#62

At what intervals do YOU change out the engine oil, on this 2013 Legacy?

I’m no judging, I’m just asking a question


#63

What do you mean no one smoked in your car? I bet your girlfriend was smokin’ hot when she rode with you! :wink:


#64

I change oil and filter once a year. I buy the best grade of Amsoil and their long life filter even though my annual mileage will be close to 15,000. As any good company, Amsoil guarantees their products. Also, the oil still looks clean using the white tissue test even after one year in service.


#65

Unless this “white tissue test” includes a chemical analysis of the oil, it’s meaningless.


#66

I rely on the oil company to do the analysis. I only say that dark doesn’t necessarily mean dirty.


#67

Interesting. It seems that oil does not “wear out” but becomes polluted with carbon and acid derived from sulfur in the oil and condensation. Several years ago there was a product on the market that used a roll of toilet paper to filter the oil. As strange as it seems, my dad experimented a bit and the paper actually would clean up dirty oil, though somewhat slowly.


#68

Realize the oil you pour into your engine is not some simple liquid that was pumped out of the ground and then put into a bottle. There are additives in the base oil that perform a number of important tasks. One example are the viscosity modifiers added to make multi-viscosity oil possible. These are long chain polymers that coil and uncoil with temperature changes to alter the viscosity of the oil and make it more stable across temperature range. These polymers are susceptible (to varying degrees) to shearing during use and then lose their ability to affect the oil viscosity. In effect, they “wear out” over time in application. There are other additives that also become compromised during use.

So regardless of what happens to the base oil, the other critical additives in the oil do become “worn out” over use and need to be replaced. Simple filtering will not correct that condition…


#69

The oil company doesn’t analyze your used oil, which can detect problems with your engine.


#70

You are correct, of course. Used engine oil is not often analyzed, but the original question dealt with how often should you change your engine oil. That depends on severity of use, quality of oil used, and of course, is the engine leaking unwanted substances into the oil. What many may not be aware of though is that there are oils on the market now that have been thoroughly tested and found reliable for really long change intervals. Mobile is the latest (i think). Amsoil has been doing it for several years. I am confident that these companies are not going to tell their customers something that will cause them (companies) to have to buy a lot of expensive engines. I like the annual changes because I do my own changes, and the filter is on top of the engine, so it makes it easy to not have to get my 80 yr old carcass under the car so often.


#71

The testing has been done on certain vehicles under certain conditions. You can NOT safely universally apply the results of that to any and all vehicles.


#72

I’ve seen a YouTube video showing that conventional viscosity went way up with age (age mostly = heat x time, I think) while synthetic viscosity stayed much more constant. They still recommended using the same intervals, though - synthetic oil still ages.

I believe that this means that the bearings farther away on the oil circuit will be better lubricated and cooled by using synthetic, because it doesn’t turn into sludge as fast. Also better mileage because it stays thinner.

Pumped oil is used for lubrication, cooling (carries away heat from bearings) and hydrodynamic films to keep the metal parts from rubbing on each other. You want good oil flow. If it was only for lubrication they could just use grease, instead of the whole complex engine oil system.

IIRC, Click and Clack said that the oil turning dark just means that it’s doing its job of holding onto the dirt.


#73

Then someone had better notify Mobile Oil and Refining Company.


#74

Old School oil analysis:
Oil gets dirty quickly; blow by rings.
Oil whitish; water in oil, possibly head gasket leak.
Oil too thin & smells strange; attached fuel pump feeding into oil pan.
Late model engines just don’t dirty the oil like those of a few decades ago. Talking about gasoline engines, not diesel.


#75

All of my recent Hondas have dirtied the oil quite a bit after 3-4k miles. Never used a drop, no engine problems.


#76

Again, is your oil dirty or just darkened by heat? Most oils will darken rapidly, but it has nothing to do with being dirty, or even diluted.


#77

Anyone remember the Arco Graphite oil?

It looks dirty right out of the can.


#78

Yes, I remember doing a few oil changes with that. It was black, thick, and gooey, right out of the can.