Last summer, my '94 GS-R started having a problem with a very light knock under load at low rpm. The problem has slowly gotten worse in that the knock is noticeably heavier now. Not really a problem - yet
- but it has gone from curiosity to annoyance. The car has 145K of hard use. Generally maintained well but may be coming due for some routine items and about 30K since its last valve adjustment. I use Mobil 1 but I only change it twice a year. Engine all original and stock except for a header to replace the noisy A-pipe. Other than the knock, the engine runs great like always.
Any ideas?