Hi guys, I have a Mitsubishi 6G75 engine with 108,000 miles. I just took the rocker cover off and it is very clean underneath with minimal varnish, except one rocker arm over a single exhaust valve is darker with varnish than everything else. I assume this suggests that this rocker arm gets hotter than the rest? What could be causing this? There are hydraulic lash adjusters between the rocker arm and valve - I was thinking perhaps it is a bit blocked and is getting less oil flow?