[Keith Briggs]

On my first switch to synthetic, I went 160k only changing the filter every 10k. The filter is everything. Filter capacity goes down as you use it but filter efficiency goes up as you use it (filtering smaller and smaller particles over its life). Strangely, a filter is doing its best job just before it fails.

Now I've tempered a bit and only go 50k between oil changes and still go 10k between filter changes (and top off of course).

BTW, I tore that first motor down and it was the cleanest motor I've ever seen.