Choreboy wrote:

.....
What's cheap and expedient? Will I suddenly wreck the engine if I keep
mowing? Will 30W oil help? Should I assume the wear is on the rod and
simply install a new one? Is it better to buy a new mower?

A) Cheap and expedient is to run it until it dies and replace it or at
least the motor.
B) Yes
C) For a very short additional time, maybe
D) No--the rod and crank will both be gone by now
E) Probably at least the engine--repair parts are normally nearly the
price of the whole engine--it is worth looking at if you're able to do a
competent repair yourself, but it's likely the cylinder walls are worn
by this time anyway, as well as who knows what else...