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Oil Pressure

1996 5.2l Jeep, the oil pressure has always been fine, I was recently towing a trailer (about 40 miles at highway speeds)and under engine load the pressure was normal but when the Jeep came to idle the pressure dropped to zero on the gauge. I use 10/30 oil. The motor has 180K miles. When the motor cools all is normal until its under the heavy load for the long distance. Trailer weight is 3000lbs.

Install an engine oil cooler or try 15w-40 oil. That 318 engine is getting pretty loose at 180K miles…

I agree with Caddyman on this. When your bearings and their corresponding wear surfaces get worn beyond a certain point the spaces between them get large enough to allow hot oil to flow through too readily and the pump can no longer maintain pressure at idle. It’s just pumping the oil through the spaces with too little resistance to do so.

I’d do both of Caddyman’s suggestions, the oil cooler and the heavier weight. The better you maintain your lubrication under high load conditions is the longer the engine will last.