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chevynut
03-26-2016, 12:44 PM
I have a new GM oilpan and it's coated/painted black inside and outside. What do they use on these? It sands well, and I think it may be epoxy. I wanted to touch up the inside where I did some repairs and welding, but don't know if it's safe to do that. Most of the searches I've done say not to put anything inside the oilpan...so why does GM do it? Has anyone heard of any issues from this coating?

Bluegrass Trifive
03-26-2016, 05:21 PM
If I remember correctly it's manganese sulfate. Our pans started being coated with it several years ago when ethanol began being added to fuel. There tends to be additional moisture and residue in the crankcase which leads to corrosion in the pan. Some vehicles have sensors in the oil to detect and trigger service engine indicators.

chevynut
03-26-2016, 09:20 PM
I'm not sure what it is, but it looks like it's a dipped coating. I have an intake manifold oil shield that has the same coating on it, and you can tell it's been dipped because every edge on one side has a thicker layer, as if that was the bottom when it was hanging. The oilpan sands nicely and I plan to shoot epoxy on the outside of it then spray BC/CC. To me, the coating looks just like the e-coat on the Taiwan floors and other sheetmetal parts.

NickP
03-31-2016, 08:26 AM
It's phosphate as I recall.

chevynut
03-31-2016, 10:33 AM
I did a little research and as far as I can tell it's e-coat. I don't know if that's "phosphate" or not, but it's an epoxy that's electrically deposited in a tank. It looks like e-coat to me, the same stuff that's on sheetmetal parts. I thought phosphate was a chemical conversion coating, and this is more like paint.