Oil filter adapter o-ring thickness

[Komet]

I've got the oil filter adapter off the '99 L31, and my kit came with two gaskets. Which one is right?

Thick, protrudes from channel (too big to seal?):

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Thin, fits loosely in channel:

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It looks like what I pulled out is a squashed thin one, but this adapter also appears to be aftermarket so I don't know if that was correct or it was simply what was available.

 

[454cid]

What makes you think the adapter is aftermarket?

I'd see if the GM gasket is available.

 

[Komet]

What makes you think the adapter is aftermarket?

I'd see if the GM gasket is available.

Says Pemco on it, I was expecting GM I guess:

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[Caman96]

Looks like correct OEM part. I bought GM Genuine kit for my truck recently and it only came with 1 O-ring, looks closer to the thin one. Also, you need to buy new bolts if you didn’t. The bolts have a built in washer and that is an area they leak, bolts need to be replaced.

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Yours appears to have oil cooler, mine doesn’t, but same principle on parts.

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[Komet]

Yeah, it's a KC4 package unit. Looks like it is the thin one with the round gasket combo, that's the same as what I took out and this one:

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says it's a fit, also looks identical. Just seems weird because it's kinda loose in the channel. Thanks for the part number pictures, I'll pick up some fresh 12553513 bolts.

 

[tayto]

not the square cut seaal. groove bigger to allow room for the oring to squish

 

[Caman96]

I wonder what that other gasket is for, looks like oil filter gasket.

 

[Komet]

I wonder what that other gasket is for, looks like oil filter gasket.

It's very close, but slightly larger than an oil filter gasket for a WIX 51060 (extended length L98 application). Here's a pic of the WIX with square cut gasket on top, AC Delco PF52E (correct filter size for this adapter) , filter adapter with other (presumably wrong for this assembly) gasket supplied in the Fel-Pro oil pan gasket kit, the correct o-ring and gasket, and the original o-ring I pulled out:

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[Caman96]

Yes, it just looks like one.