In a 1998 xj8? I can get a K&N but read the oil may get into the throttle body. What about a kit Cone filter? Are these worth the cost or just stick with the standard?

 

My opinion . . . there is not an air filter upgrade to what Jaguar engineers provided.

The K&N filter has been reported to cause air/fuel ratio issues due to fouling of the MAFS because of improper oiling of the element.

 

Ive had a K&N panel filter upgrade in mine for the last 5 years, just replaced with a new one 2 months ago and never had a single problem. Cleaned the throttle body when replacing the filter and there was very little dirt.