After running the vehicle for a certain distance usually we will change the engine oil. This will not only give engine new life with the brand new oil but will also get sludge and other sediments out of the engine.

So while changing the engine oil, I would like to know whether there is any product or process with which I can get all the oil (also the residue oil and sludge sticking to the engine) out of the vehicle's engine?

  • My question is for the guy that owns the 96 suburban. What year did you change over to synthetic oil? Was it even around in 86?
    – user20267
    Commented Aug 1, 2016 at 21:38
  • Simply change it more often, so the sludge buildup is decreased. The only time you want to get as much oil out as possible is when there's water contamination from coolant, or a failed river crossing, or a flood. Or do a sacrificial oil change with cheap/re-refined oil, and drain that to a different bottle for settling and possible reuse next time.
    – Criggie
    Commented Dec 21, 2016 at 3:32

11 Answers 11


Simple answer - no, you can never get rid of ALL of the old oil - and you wouldn't want to, as you need to keep a film of oil over all the moving parts all the time. The small amount of residual oil will mix with the new oil quite happily.

Oil flows better when it is warmer (as it gets thinner), so the best way to get as much of the sludge and residue out is to do the oil change with the engine warm - just be careful of the hot components!

  • I second that, and I would add: let it flush for a while. If you do it yourself, let it tickle down during lunchtime, or even overnight. If you really want to overdo it (and if your car has it) you can take out the oil radiator and let it trickle down as well Commented May 9, 2014 at 13:24
  • I usually drain the fluid and run two quarts of fresh oil for about 5 mins. Drain that out and replace to spec.
    – Dee
    Commented Jan 26, 2016 at 2:12

What you're attempting to do is pointless and counterproductive.

Oil will be in three locations after you turn off your car and park it for the oil change:

  1. The bottom of the oil pan- this is where about 95 percent of it will be. When you change the oil, this is what gets removed. If you have a dry sump system, you also have to drain the pressurized oil tanks.
  2. Small amounts scattered around the interior of the block/head/etc, inside the oil filter, inside the oil cooler, etc. When you take apart an engine, everything will be covered in a thin film of oil. There will be little puddles of oil trapped in odd places around the head and so forth.
  3. Stuck between the bearing surfaces. This is important.

Even when you assemble an engine for the first time, the bearing surfaces have to be lubed. The lube gets flushed out when the oil pump pushes hot oil through the bearings. Until the oil pump pushes the oil all the way through the engine, the bearings are relying on there being residual lubricration. Otherwise you get damage to the bearings.

If you could somehow flush all the oil out of the system (eg, by teeing into the oil system and flushing it with acetone or mineral spirits, etc), you would then succeed in damaging your bearings because they would be unlubricated at startup.

Just swap out the filter and drain the pan and you'll be fine.

  • I understand your point. But my question was framed keeping my motorcycle maintenance, and my ride is a small 150cc carbureted one (very simple mechanicals). All it stores is just a little less than a liter of engine oil overall.
    – BraveNinja
    Commented Nov 2, 2016 at 21:58
  • 1
    The principle is the same. The amount of residual oil is tiny and will be washed away by the next batch of clean oil. Most of the residual oil is protecting your bearings on the first post-change startup so don't remove it.
    – Jim W
    Commented Nov 3, 2016 at 21:06

I've always had good luck with the kerosene method. Which is adding about a quart of kerosene to the oil and brining the temperature of the engine up to running temp for 5 minutes then drain. Then I use Mobil 1 full synthetic oil and a new decent filter. After 5000 miles I change the filter. Then at 10,000 miles I change the oil and the filter again. My '86 Chevy suburban has 517,402 miles. It's hard to fight with success like that.


You could use either Seafoam, or a home brewed seafoam alternative in your crank case to clean it out.

How to use SeaFoam to clean your Engine – The RIGHT way!

OK, you’ve got another can of Seafoam, right? Good. This can is going to be used to clean oil rings and lifters, clean built-up oil residues and contamination from the crank case, and clean the PCV system. You’re going to use 1.5 oz per quart of oil. Check your owners manual (or, again, ask on the forum). If you have a 5-qt oil capacity, you’ll be using 7.5 oz of Seafoam (roughly half a can). While the company claims you can leave the Seafoam treatment in your crankcase until your next oil change, I’ve found that most engines with higher miles have a LOT of nasty buildup, which can really take a toll on your oil filter. Therefore, I like to do an oil change roughly 50 – 100 miles after adding Seafoam.

The other half of the can? Add it to the crankcase after you change the oil if you had a lot of sludgy buildup, OR dump it in your fuel tank at your next fill-up. Seafoam is safe to leave in the crankcase with clean oil until your next oil change, and it’s also a great product to clean your injectors and fuel system. In fact, it’s even credited with helping remove some of the deposits that cause a faulty fuel gauge reading in some cars!


I have found before you go and get ready to change your oil an old Timer showed me this trick , Get a Heavy Speaker Magnet ..About all cars not all have a Magnet pad built in the bottom of oil pan or you can buy a Service Plug to catch all fine Segment in oil any way about 3 days or longer take the round Magnet place over the fill plug or near it don't worry about it falling off be sure it's a very strong one . Then when your ready to remove the plug and Drain the oil you will be surprise to what will come out . Hope this helps anyone to try your Car will like that the old fine shavings are now removed.

  • How does this work for aluminum oil pans, as many vehicles these days are equipped with them? Commented Dec 13, 2015 at 13:00

There is a popular process to get just about all the oil and sludge out of an engine.

Though it is usually done after engine disassembly.

You soak the dirty engine pieces into a hot tank of sodium hydroxide (lye) solution and other cleaning agents. The liquid will chemically react with the oils in the engine and remove it in the process.


I've rebuilt a lot of scrap yard engines and those just needed refreshing . I found if you could start them , add about a quart or so of kerosene and bring them up to operating temp run 5 min and dump while oil is hot worked best for me. It will even brake up hardened sludge from overheating


So while changing the engine oil, I would like to know whether there is any product or process with which I can get all the oil (also the residue oil and sludge sticking to the engine) out of the vehicle's engine?

Yes. Change the oil filter. There's a surprising amount of oil in the filter as well as all of the "sludge" (i.e., particulates and other solids) that have collected in the oil.

Will this get rid of all of the "sludge" in one go? No.

Will it make a significant difference over time? Yes. The new clean oil will be better at capturing anything that's floating around the engine and the clean filter will be better at trapping it. Changing that dirty filter will get that collected junk out all in one go.

Also, unlike many suggestions you'll hear, changing the oil and filter will never make your engine worse.


It's costly but the best way to safely clean almost all old oil is: change oil and filter, drive for 50 miles or so; change oil a second time (not filter) drive another 50 miles; change oil a third time, (not filter) drive 50 miles; change oil a fourth time and filter and your done. This is really over kill and not necessary but it will completely clean practically all old oil. Also you could add a special crankcase oil detergent during a couple of the changes. I've never done it and won't ever do it but if someone is determined to go above and beyond what is necessary and they have money to burn this is the way to do it.


Pump it out.

You can get electric or hand pumps, ones that are already built into a tank or ones that are just an inlet and outlet hose.

It wont get all of the sludge out but it will get more oil out than draining from the sump plug will. It is time consuming at best so I've only done it a hand full of times (twice on a car with a rounded off sump plug and once because I felt like it). You stick a hose down the dipstick tube until it reaches the very bottom, then pump it all out.

The three cars I've done and refilled kept completely clear oil on the stick for a couple of weeks so there cant have been much old oil still in there to mix with it.


I had some serious black sludge after not changing my oil for over a year. Ran castrol gtx in it with k&n filter for a month. After that, I did another change with my preferred oil. The "new" oil has about 8,000km on it and still looks very clear.

Castrol advertises the "tri-shield technology" in the GTX oil and from experience, it does seem to work as advertised for getting rid of sludge at least... and I'm a sucker for cheesy commercials: https://www.youtube.com/watch?v=uFsRVcQuTQo (tri-shield ad)

Doesn't completely answer your question in removing all "residue oil" but you wouldn't want to do that anyways. The oil also protects the parts from oxidization.

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