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Sealing lightly corroded aluminum engine parts with crude oil

Q. Hello,

I have a cargo van with bare aluminum parts exposed. I have the idea of obtaining some crude oil sludge from the sea shore, using mineral spirits as a thinner, then manually painting a single coat onto the parts. I suppose the coating will become "dry" over time much like road asphalt. My concern however comes from the blisters I often see when steel rust forms under a new paint job. Will a similar phenomenon occur if aluminum corrosion is simply sealed under a layer of said crude oil?

Thanks,
Alan

Alan Mattia
- San Diego, California
September 27, 2022

A. Hi Alan. Congratulations on your photography skills -- you've managed with one photo to convey the exact situation very well.

There's an old saying from Bridge that "a peak is worth a thousand finesses"; to assume that crude oil mixed with mineral spirits will dry into a decent coating over time, or to ask the internet whether it will, is no substitute for trying it on some scrap first ... and seeing whether it does or remains a runny slime

But in general, trying to seal over corrosion, dirt, salt, and water doesn't work, both because the coating has nothing solid & substantial to adhere to do so little bits flake off, plus you haven't removed what is causing the corrosion.

I think sandblasting the aluminum, or at least pressure washing it, followed by paint made for use on aluminum will be far more satisfactory. But good luck in any case, and if you do the crude oil treatment, please come back and tell us how it went. Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey

! Crude oil preparation: mineral spirits, white Coleman camping fuel, and Xylene [on eBay or Amazon] as solvents for crude oil.

Said preparation applied with cotton ball on tested areas shown.

Comments: the brown liquid absorbed by a wicking action into the white scale.

I hope most disintegration of aluminum by whatever chemical means, be it salt, dirt, and/or ambient moisture is arrested.

Alan Mattia [returning]
- San Diego
February 5, 2023

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