How to check for sludge ?

[George]

As a data point, I have owned my '91 200 Avant from new and after the 50K
warranty period, I switched to Mobil 1 synthetic. I have always run 15 to 20
K miles between oil changes and changed the filter every time. At 308,000
miles I replaced the valve cover gasket ( second time).  That exposed the
top end, which was clean as a whistle. (I do live in the temperate climate
of Monterey, CA.)

A few months ago I pulled the injectors for the first time and sent them off
to be reconditioned. The plotted condition showed a 1.5% difference between
pre and post rebuild.  Recently 034 did some work which included putting the
car on their dyno. It came in at factory spec for horsepower and torque. So,
at 313,000 miles the combo of synthetic oil, regular doses of fuel system
cleaner, and other routine maintenance, does pay off...........

Not sure what this means in the dino/synthetic discussion...............

George Sidman