Reuse oil?

Some Baldwin filters for trucks have a bypass built into the cartridge. Some of the oil is sucked through a 2 micron filter enclosed in the same canister.
 
Magman said:
The “TP” used had to be non-biodegradable. That industry changed too.
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They have introduced rapidly dissolving toilet paper. Just how rapidly are we talking about? Because I don't want to play "beat the clock" in the thicket.

Bill Engvall
 
I’ve heard that used oil accumulates acid or turns acidic. Acid eats bearings.
 
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As the OP pointed out, you are not running the same oil for hundreds of hours. Our engines USE oil, so you have to top up every so often. You should also change the filter and that removes some of the oil.

There was a website a number of years ago where they were running a car without ANY oil changes. Just a quart every filter change and whatever was needed for top up. They were running BlackStone oil analysis every 3000 miles.

IIRC, there were over 200K miles when I last saw the site. And the engine and oil were fine.

My local FBO uses waste oil heater for winter (Maryland). They generate more than they burn.

Back in HS and college I drove a Fiat 850 Spider. No oil filter at all. But it centrifuged the oil in the crank pully. Every oil change, you would remove the cover and clean out the grey sludge that was packed hard into the hollow pulley. Probably mostly lead.
 
Let'sgoflying! said:
What happened to shearing the long chains and change in viscosity, which was previously discussed widely?
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AV8R_87 said:
Multi-grade oils will get sheared and their properties will degrade.
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It depends on the engine. Some engines shear or degrade the oil before it gets contaminated. Others contaminate it before they shear or degrade it. Whichever happens first, the oil needs to be changed. Running 20w50 in my O-360, UOA at 50 hours says the oil viscosity is still in the 40 to 50 weight range. So this engine definitely contaminates the oil before it's sheared or degraded. That's no surprise since it's air cooled engine and running leaded gasoline.

With modern gasoline engine cars, the opposite often happens - oil contamination is so much less, you can often run the oil until the engine shears or degrades it. With synthetic oil, that can be a loooong time (10,000+ miles in some engines).
 
dcat127 said:
So I went down the rabbit hole on YouTube watching grease monkeys that are adding additional filtration or centrifuging engine oil on their trucks and are running the oil for much longer than the manufacturer's recommended interval. The theory seems to be that engine oil's lubricity far outlasts a normal oil change interval, the main reason to change it is to get rid of the contaminants. They are not doing this without data, as they are getting regular oil tests done. I mean ok, ok, every now and then they may blow up an engine, but that is likely unrelated, regardless what is an engine every now and then in the face of advancing science.

Seeing how expensive aviation oil is, why don't we run it through a centrifuge every 50 hours and put it back in? Aircraft engines typically use more oil than an automotive engine, so the makeup oil added between oil changes likely adds more than adequate replacement of the oil. I mean it would save me like $100 per oil change, I could pay off decent quality centrifuge in like 50-75 years, and everything after that would be pure profit. Or I could sneak into North Korea's nuclear refinery in the evening after they go home and "borrow" their centrifuge, I hear they have a decent setup.

My Pa32 POH says that if the engine is used with a full flow oil filter that you may change the filter every 50 hours, and only replace the oil every 100 hours. This also seems to be a nod to the idea that it is more about removing the contaminants than it is about the oil wearing out.
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Seriously? You're thinking of reusing $100 of oil in a $50,000 engine which, if it fails, causes you to fall out of the sky?

Dude, you've got the wrong hobby!
 
Albany Tom said:
I'm kinda waiting for someone to say they run their airplane on peanut oil, so they can strain that out later and make french fries in it.
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While I don’t think he ever became a pilot and he has long since expired, so he cannot comment, I believe Rudolph diesel did extensive successfull work on running engines on peanut oil.. though as a fuel not as the lubricant.
 
oil does not dissolve paper like water does, that's the main reason it's such a good filter.

I used to filter used oil through a poly bag, about 8 inches long and made to fit over the top cover or a 375 gallon tote.

while the filter did remove particulates it doesn't do anything to revive the additives or restore the broken hydrocarbon chains that make oil slippery.
 
Albany Tom said:
I'm kinda waiting for someone to say they run their airplane on peanut oil, so they can strain that out later and make french fries in it.
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Reminds me, quite a number of years ago I worked as a tech at an appliance shop. This lady brought her sewing machine with a complaint that it was very sluggish. It was covered in a sticky substance. We asked her, what are you lubricating it with? Her response... "it can't be that, as I am using the good kind of oil...Organic olive oil".
 
MRC01 said:
With modern gasoline engine cars, the opposite often happens - oil contamination is so much less, you can often run the oil until the engine shears or degrades it. With synthetic oil, that can be a loooong time (10,000+ miles in some engines).
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What shears in multi viscosity oils tend to be the viscosity improvers.

Most car oils these day are synthetic, which are much more temp stable, so have little need for viscosity improvers.

My 2002 BMW M3, when you reset the oil service counter, starts at 15,525 miles to the next oil change. Interestingly, that number if modified as you drive. The interesting part is, BMW found that the best indicator of oil life was fuel burned. IIRC, it was 600 gallons. If you drive hard, you burn more fuel and the oil service counts down faster.
 
Pinecone said:
What shears in multi viscosity oils tend to be the viscosity improvers.
Most car oils these day are synthetic, which are much more temp stable, so have little need for viscosity improvers.
My 2002 BMW M3, when you reset the oil service counter, starts at 15,525 miles to the next oil change. Interestingly, that number if modified as you drive. The interesting part is, BMW found that the best indicator of oil life was fuel burned. IIRC, it was 600 gallons. If you drive hard, you burn more fuel and the oil service counts down faster.
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Yep. Another factor is contamination. Our aircraft engines need an oil that can hold contaminants (especially lead) in suspension. Synthetics don't do that as well as mineral oils. Modern cars don't contaminate the oil like our aviation engines do, so they don't need that. Synthetics are great for that application.

My opinion is that there's no point to using synthetic oil in our aviation engines because the engine would contaminate it long before you could take advantage of its benefits.

Interestingly, Lycoming says if you run unleaded gas, you can double the oil change intervals to 100 hours. But you still need to change the filter every 50 hours - and cut it open to inspect.
 
We generate large amounts of used oil at work. On the last visit of safety clean, I asked them what they were doing with all of it, I was under the impression it was burned to make electricity.

The driver told me that everything we gave them was sent to a refinery and refined to make oil that goes back on the auto parts store shelf.

Sounds to me like the large version of what the OP is suggesting. Myself, I’ve got better things to do.

I used to burn all the old turbine oil and jet fuel in my diesel truck.
 
There used to be some diners around here that never cleaned out the chili pot. Just keep adding more and keep it on simmer.

Did the OP ever run a diner?
 
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