moosestang

I don't need any studies or testimonials to know my car runs better/smoother after an oil change. I change mine every 3k miles with mobil 1.

GidyupGo

Me too. Then we know that new oil is ALWAYS better for an engine than oil with mega miles on it. Money isn't an issue to me when oil life is a concern. I do lay awake at night wondering if I am wearing out the threads of the drain plug though.[X(]

Nuke

I've been involved with oil analysis and oil "discoloration" from combustion is NOT an indicator of degradation of an oil's protective properties. Anti-oxidants in synthetics don't break down that soon. And dirt and crud, well,their elimination or reduction isthe function of the oil filter.

GidyupGo

Then you know that acid begin forming the first time your start an engine after an oil change. It is a downward spiral from that point on. The longer an oil is in an engine, the worse for wear. And, filters only filter down to a specific micron and can't get all abrasives out of the mix. I am in this engine for the long haul and will pass it down to family members without any major interior work needed.

SCCAGT

I shudder at the thought of Fram, Pennzoil and Quaker State. nuff said.

Gene K

I bet he alsoknows that engine wear INCREASES with fresh oil.No its notjustflushing out old deposits. There are actually a couple of SAEpapers on it if you care to buy them.But as long as you dont take it to extremes (Changing every 300 mi) you are not going to be able to tell the difference.

That said 3000 mi with any modern oil, 5000 miwith a GII or better, and 7500 mi with a synthetic are pretty much no brainers.Thelast timeI tried todecide onminimum wear for an engine basedon total wear metal generation it appeared total wear would be least with a conventional when changed at5,500-6,000 mi and9,000-11,000 mi with a synthetic.

The bottom line is you can use a Colt 1911 (3000 mi OCI with Dino) or a Glock (10,000 mi change with extended drain synthetic) and either will get the job done.

There are always new things to be learned. I used to run 10,000 mi oil changes in a Heavy Diesel and decry all those guys who take a chance on running 15,000 mi chamges. Why my engines lasted a million miles and I just new theres would die at 700,000. Then I figured out they would last at least 1.4 million miles on 30,000 mi changes. BTW thats on conventional. I know guys that have bypass filters and synthetic and never change the oil until analysis says so. Somewhere between 80,000 mi and 300,000 mi usually. Some of them have 2 million miles on engines.

GidyupGo

No time soon is someone going to convince me that used oil lubricates better than new. Not going to happen.The only way to know exactly how long you can run on used oil is to have an oil analisis done. Even then. it will only tell you wear metals and trash in the oil and it will suggest an oil change time frame. It is still up to you to determine what interval you are comfortable with.

Nuke

Oil analysis provides more than just "wear metals and trash in the oil". It alsoprovides how far the oil and additives have drifted from their baseline values, ALL of which provide the basis for determining end-of-life. However, I couldn't agree more with your statement "It is still up to you to determine what interval you are comfortable with."

GidyupGo

Yes, thanks for that clarification. The OA will tell how "worn out" the oil is. What do you think about the statement that used oil lubes better than new? Is there some sort of molecular miracle that happens with used oil that I am unaware of?

Nuke

With my "vast" knowledge on this topic (yeah, right) even THAT one baffles me. But from things I've seen regarding lubricating oils, I wouldn't totally discount it. I'll hold my tongue until I find data worth reviewing. As for now, it doesn't apply to my application of oil so, no offense, it's interesting but useless info for me.

Besides, I'd rather be putting the oil to the testby running my Stang then talking about oil...