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What is this Gray oil?

Mopar Hunter

Well-Known Member
Local time
8:16 PM
Oct 31, 2017
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Mountain Home
On my friend’s 383 with 906 heads rocker bolts, both sides of the front rockers. First time they’ve ever been removed. The rear other bolts on both sides look fine. Head gasket leaking?

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I have an old Chevy that’s full of that crap- 1963. Never been apart. I did a fuel pump and scooped out this antiseize looking grease/sludge with my fingers.

I chalked it up to old fuel and oil residue. Lead maybe.

But I’m curious what the consensus is here.
Hate to say it, but it looks like bearing sludge - but I imagine any old engine would have some of that?
I've seen that too and the engines were pretty well worn.....and have no idea why it only shows up in certain areas.
Its in the wrong place to be bearing sludge. I've also seen that on original builds. I think its some sort of assembly lube. FWIW, those particular bolts don't get much torque.
Bottom of oil caps , even on newer cars

Was always under the impression , condensation mixed with the type of oil that sits stagnant for along time ???

Tan Brown Gray In Color
If it's an old engine that had leaded gas for fuel, it's lead. My aircraft engine always had lead in the oil.
They say it's Lead, whoever they are. I have seen it on original engines that haven't been apart. Will be on all the bolts inside the engine.
Sure looks like anti-seize, mechanic could have inserted some bolts before remembering the anti-seize being on shop rate not going back to put it on the other bolts. Lol, no idea; just one guess out of many..
I wouldn’t be surprised if you dead on here…
I wouldn’t be surprised if you dead on here…
Done it myself and when using di-electric grease - "Oh damn...yeah I wanted to apply it". Being MY ride, I went back over my work to re-work it.
I ALWAYS find this grey gooey crap under bolts as I disassemble and clean engines. It is a by-product of the oils of yester-year. The engines also give off an "Old" smell too when they are taken apart and washed. I would have to say that after about the 80's or so you don't see it anymore. If an older engine is not like that, it has likely been disassembled before.

When I blow out bolt holes, I get that **** all over my arms and face...
Lead. Used to find a lot of the light Grey sludge in the bottom of oil pans. Old gas used to have a lot of tetraethyl lead in it.
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