fouled O2 sensor

[billy triton]

My O2 sensor when out my ? is could it be the oil I' m using I have a 2000 150 OX 66 since I've had the boat I've been using quicksilver synthic blend and putting some sea foam in the gas. I 'm not sure on how much seafoam to use per gal or per tank I've just add about a inch or so with each 1/4 tank of gas is this to much not enough how is this measured

[Tr21Pd]

1 ounce to 10 gallons i believe .....

http://www.seafoamsales.com/

[SEAHORSE]

Here is a link to learn more about the O2 sensor, and how to service it.

http://www.boatsetup.com/O2sensor.pdf