Jeep Repair: 1998 JGC Laredo V8 5.2-possibly burning oil, head gasket, spot at home

Question
have approx 85000 miles
get oil chg'd every 3000miles
after 3 seperate oil chg's(by 3 different shops)- when ck'd oil (usually approx 1500-2000miles after having oil chg'd)there is NO oil registering on the dip-stick. since the 1st time this happened, i have ck it often & for the 1st 1000miles or so, the oil level is exactly as it should be. i have never ck'd it & had it register low - it is either full or empty. do not get a warning light, don't notice the smell of oil burning, have never noticed a leak or any spots where i park (park in the same spot at home & at work)& find it hard to believe that it is burning such an excessive amt of oil in a short period of time. also, the last shop that chg'd the oil said that the drain cap was not tight at all when they went to drain the oil. so, he assured me that he had tightened to specification. he also informed me that this cap is not something that would work itself loose. so, i've been 2000miles since this last oil chg AND after the temp gauge along w/ the warning light brought to my attention a problem with my cooling system the other day (which appears to be the water pump) i ck'd the oil while under the hood & found that it was empty again. i am very concerned - any ideas of what the problem could be? could i possibly have a leak that only occurs while driving (thus leaving no puddles) and yet gives off no smell?
thanks for any advise you can give!

Answer
Hello Michelle,


   It sounds like one of those hard to diagnose vehicle problems. Something to look at first off, would be your coolant. It is possible that the head gasket is leaking oil into the coolant. In this case, you would see no leaks. If the green coolant is dark or has oil in it, this is a sure indicator. Another thing to keep in mind is that technically, when the dip stick for the engine oil shows nothing, you are probably just over a quart low, not completely empty, which is why you don't get a warning light. One quart makes the difference from full to add. The only way to tell for sure how much you are loosing would be to add oil (when it shows nothing), and see how much oil you need to add before it is full. The 5.2 V8's oil capacity is 5 quarts. It is also possible that the oil is leaking while you are driving because of the circulation that isn't occurring while you have it parked. I have found two methods to work well with oil leaks. One would be to place a big piece of cardboard under the engine and run the Jeep for about 10 minutes, revving occasionally. Take a look at the cardboard for any oil drops. The best method is to use a UV leak detector such as the one shown here:  http://www.jcwhitney.com/autoparts/Product/tf-Browse/s-10101/Pr-p_Product.CATENT...  . I hope I have helped you. Let me know if you have any other questions, and I will be glad to help. Good luck with the JEEP! --Jeep4x4man