I can't answer your question, but I must be a real dope. I've used 10 different engine oils in the 18 years I've owned my Ridgeline.
How Long Would You Run 2 or 3 "flush" OCIs When Changing Oil Chemistries?
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garageman402
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So maybe running the 2L actually helped since the subsequent UOAs were consistent with the first? I wonder how it would compare to not running the 2L.
Thanks for the info!!
garageman402
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The extra oil is for high rpm when more oil is in the head & hasn't drained back yet, windage when cornering, & cooling. None of which applied in my driveway. I think @Jetronic is right that idling essentially cold oil won't do much more than clearing the heads of oil pockets. Probably didn't get much out of the lifters, either...
I realize that, but I'm old school. Over the years there were a few members here posting after they drained the oil they'd leave the drain plug out and start the engine and run it a short period in hopes of getting more oil out. Practices like that scare me. Others would leave the plug out and pour cheap oil in to get more dirty oil out. OK. Many of us have various reasons for doing things, it keeps the board interesting.
Owen Lucas
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This is hearsay that I read in a YT comments section: Apparently Chrysler's engineers tested motor oil to see how long many changes it took until any trace of MMO was removed. Supposedly it took like 7 or 8 oil changes until the oil was MMO free. In reality none of this matters unless this is an F1 engine or the sort IMHO.
garageman402
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Ya, I've cranked in flood clear mode to clear the pump, & actually started carb engines for a half second. Seems more oil shoots out the clean side of the filter, maybe from the lifters compressing? Then use flood clear to prime the system or short starts if no flood clear available. A carb engine will usually stumble for a bit before really running so RPM is low. Too lazy to pull the coil wire..... But I've heard early HEI systems would be damaged if run without a load, maybe just another myth.
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garageman402
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I saw the guy on YT who did 6 oil changes & showed the drained oil in milk jugs. It got progressively clearer until about the sixth where it was clean. Hope he got enough clicks to pay for 7 gallons of oil, lol
Keep in mind that oil blenders (even big ones like Mobil) will change formulas with some frequency. So, for example, the Mobil1 EP you buy today may have different base stocks and additives than that you bought a year ago. So I wouldn’t worry about it.
That's a good point, and the boutique oil companies can do it too. Maybe with a tiny bit more transparency, maybe.
I wouldn’t “flush” anything. I’ve changed oil brands all the time.
Buy your new oil, change the oil, at your normal interval, change it again.
Many years ago, when I first joined BITOG, I posted pictures, that are now no longer available unfortunately, of an engine that had been run on oil that was bought on clearance sale.
It was a different oil every time I changed it. Pennzoil, Mobil, Castrol and others.
The engine was in a 2006 Toyota Corolla. An engine well known for sticking piston rings.
But this engine didn’t have any sticking rings, and in fact it was running strong at over 240,000 miles when the car was donated by my stepdaughter to a needy family.
So, no flushing needed. Pick the new oil. Change the oil. Don’t worry.
Buy your new oil, change the oil, at your normal interval, change it again.
Many years ago, when I first joined BITOG, I posted pictures, that are now no longer available unfortunately, of an engine that had been run on oil that was bought on clearance sale.
It was a different oil every time I changed it. Pennzoil, Mobil, Castrol and others.
The engine was in a 2006 Toyota Corolla. An engine well known for sticking piston rings.
But this engine didn’t have any sticking rings, and in fact it was running strong at over 240,000 miles when the car was donated by my stepdaughter to a needy family.
So, no flushing needed. Pick the new oil. Change the oil. Don’t worry.
How many oil changes are needed depends on the definition of no old oil left. Does that mean 1%? 0.1%?
Knowing how much oil is replaced for an oil change and how much is in the engine, the math is easy. If the engine has 5 qt capacity but only requires 4 qts for an oil change (a typical value, check the manual), after one oil change it is still 20% old oil. After two oil changes it is 4% old oil brand, and after three changes it is 0.8% old oil brand.
Engine oils have been mixed from the beginning - very few, exceedingly few, have worried about it, including car manufacturers and oil producers.
Knowing how much oil is replaced for an oil change and how much is in the engine, the math is easy. If the engine has 5 qt capacity but only requires 4 qts for an oil change (a typical value, check the manual), after one oil change it is still 20% old oil. After two oil changes it is 4% old oil brand, and after three changes it is 0.8% old oil brand.
Engine oils have been mixed from the beginning - very few, exceedingly few, have worried about it, including car manufacturers and oil producers.
Owen Lucas
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Bit anal, are we?
Well, if you’re on an oil website that description suits you, too.
garageman402
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That's a great video, but not the one I remember. Maybe it was just a photograph, but he had regular one gallon milk jugs lined up, no flashlight from behind. The jugs weren't clear like yours, they were the semi-transparent cloudy jugs, but you could still see the color changes.
"Should" not be damage, but you are pushing your luck to the wall. Running an engine 2.5-3 qts low is a really bad idea. And for a flush?
My suggestion is you don't worry about this I change oil brands at about every OCI my last car I drove for over 16 years. Changing oil chemistries is not an issue.
Change oil. Start engine, running up to temp, stop engine, change oil again. Basically it takes about 20 mins total.
To be honest, this is not something I have ever really thought about, because I just don't see it as an issue. Like many have said on this thread already, I buy what I get deals on mostly. Quaker State, Pennzoil, Mobil, Havoline, Supertech, Castrol, STP, NAPA, whatever.
I'll chime in, why not run the engine for a few minutes after it's fully drained! If you're running slick 50, it shouldn't be a problem! Right?
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