I have a 2002 mazda b2300 I bought it two years ago with 135,000 km's and after a couple oil changes I noticed an occasional knocking sound from bottom end of engine but seemed like just normal combustion" barely noticeable". The truck now has 205,000 km's on it and the sound is getting worse, especially when rpm's get low like when I turn steering wheel and the idle drops for a second and knockity knock. I recently had rebuilt the top end so the engine has all new valves, tappet clearance is good, oil pressure is good timing chain and tensioner are in great shape.

I got a stethescope to hear the sound from bottom end and I can hear the knocking sound clearly from oil pan area. I am pretty sure it is a rod knock and I can hear clcking from probably crank bearings but I don't have the time and money to pull the engine out and get er fixed. Is there a poor mans way of of getting more life out of this engine like an additive or maybe a heavier weight oil before I break a rod or wrist pin or spin a bearing?

I am a courier and I depend on this vehicle very much. Thank-you for any help!!