before oil change clean or dirty oil better?

From the research lab guys at Mobil I had it confirmed that a good oil cleans up deposits and holds such deposits and other contaminates in suspension. This means that an oil that gets dirty and can hold the dirt in suspension is doing what the lab guys intended. It must also hold water, and deal with acids, as well as lubricate. If someone is using a so called detergent oil and it is staying clear, something is wrong with the oil.

Richard.

I think those guys brag about their oil because they don't have the trophy wife/girlfriend/mistress, overachiever children, mansion in the burbs, country estate, yacht, bizjet, or season tickets to the White Sox to brag about.

As far as the oil looking clean, it is possible that the oil is not removing contaminants, that there are no contaminants to remove, or that those guys are exaggerating.

"Clean" is a matter of degree. No one has oil that looks brand new after

So it means the very dark Toyota Oil (at 3K-4K) I had been using was actually good? I thought it was bad and switched to Mobil7500.

A synthetic blend oil like Mobil 7500 is better than a conventional oil. An engine that turn oil black after 3000 miles is usually not in as good of shape as an engine that turn an oil dark brown in that same amount of time.

The color of the engine oil says more about the engine than it does about the quality of the oil, unless you have a really crappy oil.

However, changing to a better oil "may" not improve the condition of an engine, but it "may" keep things from getting any worse. But these things are hard to predict and results vary from case to case (no pun intended).

If you use the expensive premium oil filters on a new engine that is pretty tight, oil can stay fairly clean looking for quite a while.

Blowby is the biggest contaminant of oil, and that is directly related to mileage, since the rings in the pistons eventually wear out.

Ted

I think that if the oil really IS clean, then the motor ought to also be clean. Clean is always better.

PS I see no reason on current models to change the oil any earlier than 5000 miles, and 7500 is a safe figure. Many automakers have designs that will let oil be used up to about 15000 miles, but that number makes me nervous.

A good air and oil filter changed regularly with good oil and it looks pretty good in my Highlander for 3-4000 miles. I happen to use 5-30 Castrol & yota filters.

In the olden days, before dispersants and detergents were added to oil, it was normal for it to come out transparent looking.

That being said, if a proper, modern oil with all the additives comes out clean, what does that mean? Is it a bad thing?

It suggests that the combustion contaminants are not making their way into the crank-case; that is to say, the carbon soot and whatnot is not sneaking by the piston rings, or valve guide seals, in large amounts.

In other words, these parts are doing a good job.