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.