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BMW 3-Series (E90 E92) Forum
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Using spent oil to lubricate gaskets?
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02-14-2019, 11:26 AM | #1 |
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Using spent oil to lubricate gaskets?
I just wonder if anyone else here ever heard of this. It goes back a long time and wasn't specific to BMW or anything like that. I just remember being told by my uncle who ran a garage - you have to use THE OLD oil when you put on this [rubber] gasket. I'm sure he got it from trade craft passed from whoever he learned from... and personally I have had a pretty good run with it -- If I had to drain oil to replace a gasket, I'll lubricate the new gasket with a little bit of the old oil on my finger and never have a problem seating a gasket (does it cause it to degrade faster - I don't honestly know).
Now best practices say to use silicone oil, or fresh oil, but I have not seen one thing that explains the apparently archaic use of spent oil for this application. There has to be some explanation, whether scientific or folk legend. Just curious if anyone knows where it came from / what the scientific basis might be...? Only think I can think of is that if you have some varnish around the gasket seat that didn't get cleaned, the old oil might varnish over the uneven varnish to seal up any tiny gaps with the gasket. But that's just a guess really. |
02-14-2019, 12:11 PM | #2 |
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My view: a film of oil is fine. Personally I'd use new oil, not old...
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02-19-2019, 01:23 PM | #4 |
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I've always done this with spin-on oil filters...I'm guessing that might be what he was talking about? I've never known a specific reason for using old oil, it's just way more convenient to dip your finger in the drain pan or grab a drop from the block instead of having to open the the new bottle and try to get a little bit out of it.
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03-07-2019, 04:32 PM | #6 |
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This x100. I'll use either, but definitely a lot easier to dip a finger quickly into a pan of old oil then tilt the new oil jug and get a little bit to the tip on your finger. Only time I'll specifically use new oil is if the oil drain pan/oil was super dirty and I don't want to risk any grime from it.
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03-14-2019, 12:23 PM | #7 | |
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Quote:
But why would you on a modern BMW? All use an o-ring on the OFH cap and it is far easier to just lube the o-ring with fresh oil |
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gaskets, oil |
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