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I have a 2012 Civic with only 24K. The aluminium cast oil pan is now developing 4 to 5 inch long cracks but not yet leaking......problem not due to over tightening of oil pan screw or oil pan being hit/struck from below.
Last edited by IntrinsicFactor; Jan 3, 2019 at 01:55 PM.
Reason: up load pic
Take a metal file. File off the lines that bother you. A casting line will go away with minimal effort. A crack with still be visible after filing them down. Either way those look much more like casting lines. I see lines like that on cast aluminum all the time. I even have friends that work at a factory that makes oil pans for Honda engines. I wouldn't worry about it unless it actually becomes a leak.
Thanks very much for the info. The Honda dealership simply wants to change out the pan for $574 CDN. They never mentioned anything about filing. Less profit in filing I guess ? Again, thanks for all your help.
It depends on if they are indeed cracks, or if they are casting lines.
If they are cracks, replace the pan, but shop around for pricing.
They may be casting lines though as the others have mentioned. This is caused when a small crack appears in the casting material (usually "green sand" or similar). So though it looks like a crack into the pan, it is actually a thin metal protrusion, out of the pan surface.
I have a 2012 Civic with only 24K. The aluminium cast oil pan is now developing 4 to 5 inch long cracks but not yet leaking......problem not due to over tightening of oil pan screw or oil pan being hit/struck from below.
Those look like casting marks or "casting splatter". At my work we use Honda small engines (power equipment) and they often has those.
Often happens when the die is wearing out. To be safe you could just file a section of it and see if it is into the pan.
Thanks very much for the info. The Honda dealership simply wants to change out the pan for $574 CDN. They never mentioned anything about filing. Less profit in filing I guess ? Again, thanks for all your help.
Honestly I wouldn't be surprised if they don't 100% know what those are either. I only know because I used to work with a guy who spent decades in that industry.
2012 Civic - Cracks developing in oil pan 
