Recently acquired 2008 xB 155K on the odo, oil level showed LOW when purchased and smelled burnt. Threw in 2 qts and a splash of marvel mystery to get it to halfway mark. Ran alot smoother and less buzzy. Ran it for a around 50 miles. Just changed oil this sunday with Mobile 1 syn and new oil filter (jeez the old oil filter looked like the ORIGINAL?!?) Outgoing oil looked pitch black. Question to you seafoam guys, what amt did you add to motor oil? Gonna change my oil in the next 500 mile mark and see what it looks like.