oil pressure

searched for a bit and didnt find exactly what i was looking for.

98 XJ, 4.0 auto. 220k

with the engine warm when i am driving at about 55-60 mph i notice the oil pressure drops down very low. close to the first line on the gauge. a shift into neutral and a quick rev brings it back to normal. after a few minutes it will do it again.

i am assuming that it is just the sending unit needing to be replaced. has anyone else had this experience?

Could be the sending unit as they are a pretty common failure.

You could verify with a "mechanical" gauge, or just roll the dice and buy a new sending unit. I buy these directly from Jeep for best reliability/accuracy/mating with your factory gauge.

Probably around $30-$40 at Jeep.

Possibly the sending unit. Is it making any noise when it gets low?

Best idea is to put a mechanical gauge on it and see what it really is. Then change the sending unit if it isn't correct.

no noises or anything. it happens randomly while driving which makes it harder to use the mechanical gauge to test. im not overly worried about the oil pressure being low, just didnt know if this was common on the 4.0 or if i should really worry

My sender started doing this earlier in the year. I replaced it with a cheap BWD part (the only sender that was available in town at the time), and a few months later, it has started to do the same thing. I would recommend at least getting the pricier sender from NAPA, or the Jeep part. Retail for both is around $75, at least here.

Harbor Freight and ebay both have pressure testing kits that are fairly cheap, and you only need to see pressure at given RPMs- you don't have to drive with it connected.