I've had this problem now twice in 2 years on our 2007 CX9 and wonder if anyone else has as well. I perform my own oil changes every 5000 miles and did the first one several years back. After driving approximately 2000 miles after the change I noticed a few small drips appearing in the driveway. A crawl under the car revealed a drip coming off the bottom of the filer housing. It appeared to be just an ever so slight leak that came down the side of the filterfrom around the filter gasket. An inquiry to the dealer suggested "its because you didn't use a Mazda filter" (it was a Bosch). Next change I did I use a Mazda filter and, well, no weeping appeared. Fast forward to this week and 3 or 4 oil changes later--all with the same Mazda filter, all experiencing no problems. But, this week, again about 2500 miles after the most recent change, drips again. Inspection revealed the same issue, a weeping around the filter gasket.

Has anyone else experienced this? Lets dispense with the obvious before you respond--the mating surface on the filter housing is completely clean and nick free, the gasket on the filter appear in good shape, and I follow the age old practice of slightly lubing the gasket with fresh oil at installation. Also, the filter installation is snug, and only hand tightened-no tools. I'm puzzled--and I HATE oil drips--any ideas what is causing this and how to remedy it?

 

I admit that I am not familiar with the V6 in the CX9, but is it possible that, like the 3 series, it has a machined filter housing that bolts onto the block, rather than one cast into it, as part of the block? If so, have you checked the bolts for torque on that?

I recently converted to the spin-on filter and had to replace the original housing. I was a bit surprised to find that the "kit" came with a metal gasket instead of a paper one. If not installed or torqued correctly, I could see where this might cause a leak, perhaps even an intermittent one as you are describing.

 

Hey, thats a helpful suggestion, thanks, seems worth looking into. Could just be this is going to remain an eternal mystery tho! Thanks again.