I have a 2010 XC60 with 50000 miles and I noticed that the dipstick looks like a burned brownish color. I am assuming it is because I have the oil changed every 7500 miles as per volvos specifications. I am assuming the entire engine is probably caked up with this burning looking sludge. I was told to add 1 quart of transmission fluid and that should work? Has anyone done this, is 1 quart too much? Also how long should I leave the transmission fluid in the engine?

I have also been researching a product called autoRX and that is supposed to safely remove sludge. Has anyone used this product and does it work?

Your help is greatly appreciated.

THanks,
Sal