Compressed air to remove more dirty oil

[bwithers]

I recently heard this oil changing tip and thought it was an interesting idea. You drain your oil in the normal way. When gravity has done all it can do, you shoot compressed air in the oil fill opening creating a "seal" around the nozzle with a rag.

Since the oil drain is still open, there shouldn't be a lot of pressure build up. There could be a small amount of condensation in the compressed air.

Any thoughts? I'm still on the fence on whether it is a good idea

 

[Quest]

IMHO you'll get more oil out of your drainpan by means of warming it up before draining (the hotter the better, but not to the point of being scorching-hot).

I personally don't buy tricks like using compress air to "blow" the oil....*grin*

 

[55Test]

quote:

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Originally posted by Quest:
, but not to the point of being scorching-hot).

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Why? When I change my oil I always make sure the engine is up to full operating temperature to make sure I get as much crap out of the engine as possible, even then I still feel almost guilty that I didn't get as much as I should have.

 

[Pablo]

I'll raise my hand and say I have done this and been amazed how much more oil comes out....but I have a dual remote (full flow) and separate thermostatic oil cooler.

I don't advise it as a general practice.

I don't advise pressurizing the oil system with air. I don't advise this with unfiltered air or on a "wet day".

I'm am pretty much a freak when it comes to dirty oil. I just am not into leaving a dirty oil filter and just changing the oil. That practice may even work, but it seems absurdly insane to my bent logic. I want the dirty oil out.

SO I change my oil HOT. I let it drain for a long time. I open up the oil cooler. And sometimes I just gently blow out the oil system and get a lot of old oil.......so far I've never lost a prime or had any long dry starts (yes I prefill my filters, but that's a different thread)

Anecdotal but 252,000 miles here I come!

 

[Quest]

Well, let me put it this wey:

If you are concerned about used oil leftover in your oilpan, consider this:

20% of the "dirty" oil still trapped on the cylinder head part as "oil pools/pockets" in the cam lobe areas where the lobes use them to perform splash lubrication.

(I'm talking about OHC configuration here)


Unless you find a way to get rid of those "dirty oil pockets" (turkey baster) everytime you change your oil, otherwise, you still have "old dirty oil" trapped in your engine no matter how hard you try....


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If you keep your OCI low and you are following a very rigid tuneup/maintenance scheme then the dirty oil pocket problem can be minimized.

 

[bwithers]

Interesting points. So any extra that comes out is pretty much trival compared to the 20% in other areas of the engine.

Conclusion I'm getting is: marginal if any benefit, and there could be a downside.

 

[farang]

I use compressed air blow through oil filer hole and PCV valve opening!

4.0qt w/oil filter, w/o compressed air!
4.5qt w/oil filter and compressed air!

The oil stay clean longer! 2 weeks now and the oil is still golden honey while it will get dark just after 25miles drive!

 

[XS650]

quote:

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Originally posted by farang:
I use compressed air blow through oil filer hole and PCV valve opening!

4.0qt w/oil filter, w/o compressed air!
4.5qt w/oil filter and compressed air!

The oil stay clean longer! 2 weeks now and the oil is still golden honey while it will get dark just after 25miles drive!

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Unless you have an unusual air compressor, your compressed air has more water and other contaminants. including dirt, in it than the oil you are blowing out of the engine.

The dark oil you are getting rid of has made a bazillion passes through your oil filter, which filters far better than 99.9% of all air compressor air filters.

 

[jsharp]

Common sintered bronze filter/centrifugal water separator type pneumatic filters only remove particles above 25-50 microns in size and do a poor job removing water.

I'd rather have the remaining oil from my engine stay in my engine than the carbon and dirt that most cheap compressors and filter setups spit out...

 

[TallPaul]

If a half quart were left in the engine on a 5 quart sump, your oil overall will be no dirtier than one-tenth the way into an oci. So why work so hard for that last little bit when 90 percent of the time you are driving with dirtier oil anyway?

Seems if you are that concerned about the oil being clean, you should change it every 500 miles instead of every 5000.

But I do understand where you are coming from. I am guilty of a few times squirting fresh oil into the oil pump outlet at the filter to force that part of the remaining dirty oil down into the pan.

 

[Al]

Just pour a half quart of new oil in after the old oil has drained out.

 

[Shannow]

Something interesting that I found with my Nissan Turbodiesel.

I've always checked all of my cars oil levels first thing in the morning...forever.

Been doing that on my Turbodiesel, and read on a forum that Nissan recommend checking it hot, after it's sat for a minute or two.

Tried that, and the level was down to the "add" mark.

There's a litre (out of 7) trapped up top after the engine has been running. It takes some hours to come back down, too. After work, the engine reads a half litre high. In the morning, a full litre.

 

[wavinwayne]

Why couldn't you just rig up a suction device at the oil pan drain hole? It would create a vacuum, sucking out any remaining oil & you wouldn't be introducing any dirty/wet air into the system?

Maybe I'm all wet???

 

[ToyotaNSaturn]

Supertech oil $4.23, ST Filter $2.07. For $6.30 you can flush clean those impossbile-to-reach passages in about 10-15 minutes. Then drain it out and install the oil and filter of your choice.

 

[Ugly3]

I quit blowing oil years ago.

 

[blupupher]

quote:

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Originally posted by ToyotaNSaturn:
Supertech oil $4.23, ST Filter $2.07. For $6.30 you can flush clean those impossbile-to-reach passages in about 10-15 minutes. Then drain it out and install the oil and filter of your choice.

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That's what I was thinking. If your that anal retentive about it, just do a quick flush as above. But if your a purist, you must use whatever oil you are currently using so to not contaminate what stays in your engine.

 

[XS650]

quote:

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Originally posted by blupupher:
But if your a purist, you must use whatever oil you are currently using so to not contaminate what stays in your engine.

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Hardly, a purist pulls a tank trailer behind him and only runs the oil through his engine once.

 

[jsharp]

quote:

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Originally posted by XS650:

quote:

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Originally posted by blupupher:
But if your a purist, you must use whatever oil you are currently using so to not contaminate what stays in your engine.

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Hardly, a purist pulls a tank trailer behind him and only runs the oil through his engine once.

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Just think of the savings in oil filters over the life of the engine!

 

[Kestas]

I too used to be anal about getting every last drop of old oil by draining forever, but now that I know there's a lot of oil still trapped in the engine, there's no sense in using Herculean efforts to get maybe 20% more of the remaining dirty oil.

 

[BlazerLT]

I do understand why people would want to do this, but don't you think it is a little neurotic to go this far?