Letting Oil Drain Overnight

[cheesepuffs2]

I’ve always done cold drain. I understand that hot oil drain faster. But walk me through this hot drain gets more contaminates out. You drive a vehicle around so the engine is hot. You shut it off and the oil settles in the pan for 30mins. All the contaminants are now in the oil, right? But then let it sit overnight - aren’t the same contaminants still in the oil the next day? They are certainly not crawling back up into the engine overnight.

When taking an oil sample, it is good to do it hot because it mixes everything up so you get a good, even sample. Contaminants settle to the lowest point due to gravity and can alter results.

But how is one exactly getting more contaminants “out” with a hot drain vs cold?

I feel the same way. If anything, doesn't changing the oil cold, which allows all those contaminants to settle to the bottom, mean that all the contaminants are flowing out completely because when you pull the drain plug they're concentrated in the pan instead of possibly still dripping down from the top of the engine? I don't really think it matters either way.

 

[garageman402]

The oil drains out of the galleries that are above the oil filter. The same oil galleries that the filter's ADBV prevents from draining down when the filter is installed and the engine shut off.

Are you talking about the oil draining through the filter mount? I’m saying I have seen more oil drain out the drain hole when the filter is removed.

 

[garageman402]

I feel the same way. If anything, doesn't changing the oil cold, which allows all those contaminants to settle to the bottom, mean that all the contaminants are flowing out completely because when you pull the drain plug they're concentrated in the pan instead of possibly still dripping down from the top of the engine? I don't really think it matters either way.

I think it’s more a suspension issue. As you say, the contaminants have all settled to the bottom, so they are on the bottom of the pan. They may or may not slowly move over to the drain, especially when cold. A recently run engine most likely has the contaminants actively suspended, & the faster drainage will sweep more crap out.

 

[Scott S]

The oil drains out of the galleries that are above the oil filter. The same oil galleries that the filter's ADBV prevents from draining down when the filter is installed and the engine shut off.

Well that's going to come out either way, no matter if you put the plug in first, or break the oil filter loose while the plug is still out..

 

[BHopkins]

The last drop to fall should be the most contaminated. Once the flow from the drain becomes a trickle I let it drain for another 30 minutes.

How so? Please explain. Also curious, even if true, how would the concentrated contamination of the last few drops matter, when compared to the contamination of the massive volume already drained?

I hear tell M1 works better...

Do I detect a little bit of sarcasm, towards the BITOG community's latest choice for motor oil worship?

p.s. I'm with you on the oil extractor method, but I can't use mine on my wife's Outback. Too small of a dip stick tube.


After reading a few other discussions on this, one of the favorite subjects here on BITOG, I did a small amount of research. According the Subaru service manual, I found the 2.5 liter engine in my wife's Outback retains about 0.9 quarts (0.85 liter) after full drain. The 5.5 liter engine in the MB SL550 that I used to drive held about 1.7 quarts (1.61 liters) after full drain.

Let's use the 50 ml difference between quick and extended drain, that @Owen Lucas measured in his experiment, as no one else has reported carefully measuring it. So if we use 50 ml as the extra oil that is drained in an overnight drain, that 50 ml is about 5.6% of what remains in the Outback's 2.5 liter engine, which is a very common engine size in today's cars. In the larger 5.5 liter engine, the 50 ml is only 3% of what remains.

I'm a guy that loves data, so based upon this data, I have stayed with the practice of waiting until the drips are a few seconds apart, close the Fumoto valve, and fill her back up with oil.

 

[JeffKeryk]

How so? Please explain. Also curious, even if true, how would the concentrated contamination of the last few drops matter, when compared to the contamination of the massive volume already drained?



Do I detect a little bit of sarcasm, towards the BITOG community's latest choice for motor oil worship?

Not sure I made the 1st comment... Did I?

 

[garageman402]

always drain it hot. Really hot, like leave the car running, jack it up, put jack stands under it, break loose the drain plug, position the PIGS to protect the floor, drain pan in place, then shut the engine off and finish removing the HOT drain plug with my bare hand and craftsman tool CMMT14122. https://www.ebay.com/itm/2662099591...FcJnRrzzGSyoBbzN6IVlnVoA==|tkp:Bk9SR-rp_eOLYg
Greatest little tool since sliced bread. While the oil drains, I go in the house, shower and eat supper, sleep peacefully til am, then go out to a COLD engine, remove the filter, fill the new one up and finish changing oil.

Handy little gadget. It’s on Amazon with free shipping (for Prime members) for $19.43. eBay it’s &10.50 + $6.55 shipping. For $2.38 more I can get it Monday. Lol.

I actually bought a larger strainer to catch the hot plug, because the last time I let it drop in the drain pan it plugged the hole & the thing overflowed.

 

[BHopkins]

The last drop to fall should be the most contaminated. Once the flow from the drain becomes a trickle I let it drain for another 30 minutes.

Not sure I made the 1st comment... Did I?

No, you didn't. Not sure what happened there, but I fixed it. Thanks for pointing that out.

 

[TiGeo]

I don't take any chances and rebuild the motor so all the old engine oil is completely removed.

I like how you think.

 

[ZeeOSix]

Are you talking about the oil draining through the filter mount? I’m saying I have seen more oil drain out the drain hole when the filter is removed.

Both can happen, depending on the oiling system design.

 

[ZeeOSix]

Well that's going to come out either way, no matter if you put the plug in first, or break the oil filter loose while the plug is still out..

Of course, more oil could come out when the filter is removed. But if the filter is not removed, there certainly could be trapped oil in the galleries above the filter that will not drain out even though the sump was drained.

 

[4WD]

Of course, more oil could come out when the filter is removed. But if the filter is not removed, there certainly could be trapped oil in the galleries above the filter that will not drain out even though the sump was drained.

It’s a full quart on my 5.3L’s - filter won’t hold that - so ADBV is holding that hydrostatic pressure to the top …

 

[supton]

I use every last drop in the 1 gallon plastic container our milk comes in.
It sometimes takes near an hour to get that very last drop.
The last drop is always used to fall on one of that last dry flakes of cereal.
Stinks because a majority of the other flakes are, now, soggy.
It's important because it's the right thing to do, no?

Eons ago, dad had an oil burner. Like flirting with 100miles per quart burning. He was buying oil by the case. He'd take the empties, flip 'em upside down into a funnel, and let it drain for a day or two. Said he got an extra quart per case that way. Every bit counts.

God Bless America!
For those who gave all.

Indeed!

 

[supton]

I have to say, I'm getting a kick out of reading this thread.

But I fear some day I will be waiting behind you, waiting for the urinal to be free.

 

[JeffKeryk]

Eons ago, dad had an oil burner. Like flirting with 100miles per quart burning. He was buying oil by the case. He'd take the empties, flip 'em upside down into a funnel, and let it drain for a day or two. Said he got an extra quart per case that way. Every bit counts.

I buy 5 qt jugs and let the left over oil drain into another partial jug. Not always for a whole day, but sometimes... Heck that stuff ain't cheap!
Once whie talking too much with my grand niece I poured the last 1/2 qt into the used oil jug... I asked her to never tell anyone as my rep is tight wad.

 

[ZeeOSix]

But I fear some day I will be waiting behind you, waiting for the urinal to be free.

Gotta wait for the last drop.

 

[garageman402]

Of course, more oil could come out when the filter is removed. But if the filter is not removed, there certainly could be trapped oil in the galleries above the filter that will not drain out even though the sump was drained.

So can you tell my why more oil drains out through the sump when the filter is removed?

To clarify, the sump is draining, and slows down to a drip. When I release the filter, a small amount of oil flows out the sump drain.

 

[ZeeOSix]

So can you tell my why more oil drains out through the sump when the filter is removed?

To clarify, the sump is draining, and slows down to a drip. When I release the filter, a small amount of oil flows out the sump drain.

Ever stick a straw into a glass of water and then put your thumb over the open end and lift the straw out of the water? There is water retained in the straw until you remove your thumb. When an oil filter is removed, it can open up that part of the oiling system to the atmosphere and essentially release trapped oil in the oiling system, and if that trapped oil then drains into the pan instead of out the filter mount (depending on the oiling system design), then it will drain out the oil pan drain plug.

 

[4WD]

 

[billt460]

You guys are still gravity draining your oil? Amateurs .

2.3 gallon Manual Fluid Extractor

Amazing deals on this Manual Fluid Extractor at Harbor Freight. Quality tools & low prices.

www.harborfreight.com

Drain plugs are put on the bottom of the oil pan for a reason. Just as the dipstick tube is placed at the top of the engine. Both are designed so gravity works in your favor.

Why would you spend $100.00+ on a machine that has to fight it in order to work at all?