I've gotten into the habit of hanging out at the local Volvo independent shop recently. I've now seen this phenomenon twice and thought I'd post a warning here.

First car was an 01 XC with less than 50K on it, came in with no oil pressure. Removing the pan revealed a whole bunch of hardened black crap in the block passage just after the oil filter. The car also had a failed piston squirter valve. Well, the mechanic cleaned all the junk out, put in a new pickup tube and squirter valve, and got oil pressure again. He drove it about 200 miles, then went to return the car to the customer. Three pistons grenaded on the first hard pull out of town and the motor was ruined.

Then a week later, another car comes in on the hook with no oil pressure. Same black junk was found, but this time much less of it and it was stuck only in the pan.

Both these cars had been serviced at Jiffy-lube type places and had "Made in Korea" oil filters on them. Both the mechanic and I scratched our heads for a while but we got to looking at oil filters and the Korean one seemed to be missing it's plastic cage on the inside of the filter. We looked at an OEM filter and the plastic cage looked remarkably like the little black pieces that we'd been digging out of Volvo engines.

So our best guess is that the little plastic cages on cheap oil filters are cracking and disintegrating and that the bits are ending up stuck inside of the oil passages.

I wish I had taken a picture of that motor with the bad pistons. What a shame! Hope this information helps someone keep their whiteblock alive in the future.