Handbooks Guides & How-Tos clean used engine oil 2023-03-21

mechstdr submitted a new resource:

clean used engine oil - cleaning used dirty engine/motor oil

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Never knew you could clean your own used engine oil. Lately its hard to find non synthetic oil do you know if this will work on synthetic oil. The cost of oil has skyrocketed like 4-5-buks a qt where I am

 

Clean oil isn't the problem.
The 4 main things that make oil unsuitable for use are:
Viscosity breakdown. Engines that have big timing chains or high pressure injection pumps are bad about this. Sliding between surfaces with too much pressure breaks the long molecules that make the oil thick.
Total Base Number reduction. The base number keeps the inside of the engine from rusting. As TBN falls below 7 the oil becomes acidic, engine turns to a ball of rust.
Detergent depletion. As the detergents get used up the engine will sludge up with carbon deposits everywhere.
Detergent and TBN are linked but are not one and the same.
Fuel contamination. Fuel will cut the viscosity of the oil and dilute additives.
Fuel contamination likely means the engine is producing more soot and more acids. More soot is using up detergents faster and more acid eats up TBN faster.

For my wife's direct injection car I fill the 5w-20 oil just past the low mark when I change the oil. Then every 1,000 miles I add a little 20w-50 weight oil. By the time I change the oil after 7,000 miles the oil I have added a quart of 20w-50 and is at the full mark which makes it one fifth 20w50. The used oil barely specs as 5w-20 oil. If I just run 5w-20 oil it comes out as like 0w-11 weight after 6,000 miles.

 

It's also basically IMPOSSABLE to remove all the contaminates once the oil starts breaking down! Also, many diesel engines intentionally soot the oil as a form of lubrication enhancement, Mercedes, Isuzu, and Detroit are LONG known for doing this, and it really does work, but it will absolutely destroy oils not blended specifically for this! Synthetic Oils are a whole different game, and what's really tricky is the blended Synthetics, which unless you really get down to the chemical compound level, cannot be cleaned!

 

You can clean the oil and repurpose it. Like used truck oil, clean it and then use it for lubricating harvester shears, maybe spray it on the frame of the truck, pour some of it in a bucket of mason sand and stab your cleaned shoves in it to keep it from rusting or use it as chain oil

But i wouldn't clean engine oil to then put it back into said truck engine due to break down in original properties discussed above.

 

I thought harvester shears used oil that's so thic it's graded on the grease scale?
I use used oil to dip my bar when cutting dry wood.

 

Some waste oil heaters with exterior air and exhaust vents put it to good winter time use. They are simple machines and plans everywhere.

 

I should have stated that the info was for use only in dire circumstances when fresh clean oil is unavailable, i didn't intend to say it was for routine use. i myself have not used that trick, YET, but if push comes to shove, it's just one more trick in my bag of tricks. as always YMMV.

 

I used to sell Sun Oil, re-refined (used) oil sold in bulk. The gas station would get it in 55 gal drums. It was like $0.20/qt. Just the thing for an old Ford Falcon with no rings....

Cool stuff for the late 60s.