Oil cooler adapter O-ring


Active Member
Jul 5, 2003
I have to replace the o-ring in my oil cooler adapter. does anyone know the part # for this and if they are still available from GM? also, how do you take the adapter off to replace the o-ring?
GM part # 25530999 ... I ordered mine from the local Buick parts counter...on and off more times than I can count and no leaks in 4 years. It was @ $4.00 back then.

R&R the oil filter screw-on adaptor with your 1 1/8" 6 point socket (same size as the crankshaft balancer bolt).

HTH - Jimmy
If you don't want to wait for one at a Buick dealer you can get a nice one at NAPA.

Comes with a Chevy truck one too. :D

Do a search for the NAPA part number I posted it two months ago.
Here's a post I made last June:

When my oil cooler o-ring started leaking on me late one evening, I did some scrounging in my garage and came up with the gasket out of an oil filter. Used my dremel to narrow it a bit to fit it into the oil cooler adapter groove and I was back in business. I rather like the oil filter gasket since it has flat surfaces for sealing against the adapter and the oil pump housing. It seems to me that it is less prone to being twisted, pinched or shredded than the original o-ring. It certainly works well for oil filters, too! My only caution is to be sure the oil filter gasket is not a tall one such that it leaves a lot of gasket exposed once screwed into place. High oil pressure during cold starts can push the gasket out of place if it is not well secured by the grooves in the adapter.

Buzz White in Houston, TX (sumnerw@flash.net)