The TOC is added automatically if you have 4+ headers in the body but can be forced for smaller articles by adding __TOC__ where you want it to be.
Headers are defined like this:
== LEVEL 1 HEADER ==
=== LEVEL 2 HEADER ===
==== LEVEL 3 HEADER ====
Article on prewash look good - I've renamed it to just "Water Prewash" leaving the 7% out of the title since it's mentioned in the body plenty, plus it's more URL friendly that way and will automatically be connected to a hanging link in the drywash article
I'll look at merging your drywash and my drywash articles too.
Edit: Ah, I see yours is on drying previously water washed biodiesel, not the same thing as hardwood drywashing after all - maybe this needs to be clearer.