This is the same guestion, we got an oil change,all levels are fine ,went on a 5 hour trip, got out,when we went to start the car, it would not start, it cranked,but will not turn over,when we first tryed to start it the oil pressure light came on, we let it sit overnight and tryed to start it again, no light is on,but it will not start, any thing anybody can suggest would be much appreciated as we are stuck out of town...

SOURCE: Long cold cranking before start

You have a very common problem; your fuel pump needs replaced. Inside the outlet of the fuel pump is a "check valve", that holds fuel pressure from draining back to the tank. What you have happening is the fuel has emptied from the lines and the injector rail; the long cranking period is the time that it takes for the fuel to be pumped back to the engine. Replace the fuel pump & your problem will go away.

SOURCE: oil pressure light on and wont start

Well I had the same problem and wow was I surprised man. I have a code machine that plugs into my car and tells me what wrong with it then I fix it. It read that I had a misfire #1 so that means my spark plug is dirty or something like that. When I took off the spark plug it was smashed in that was a good sign.. I called a mechanic friend of mine and he said that my head and piston were damaged but would not really know unless he took it apart. What he said was true and cost me a great deal of money..!!!! Now searching the web I have found that there many jeep liberty with the same problem just different spark plug locations so I wonder if Jeep knows of this issue but will not acknowledge it.. If you need more information please email me at [email protected]

Check out this link regarding your issue..!!

SOURCE: 'Check gauges" light comes on and oil pressure gauge reads zero.

The first thing I would definitely do there is change the oil. Used oil tends to loose lubricity and becomes thinner than it was when in the container. When hot, it becomes even thinner and will cause a drop in pressure.
Most jeep engines hold around six quarts of oil, so by adding what you did the new oil helped a bit but cannot correct the problem.
I would change the oil and use either a 20w50 oil with a pint of Marvel oil, or change to a good synthetic with a container of Lucas additive. It is possible that whatever oil you have been using is causing a carbon buildup that is beginning to block off the pump pickup screen. Either of the above suggestions will help with that. In engine oils, price is important...cheaper oils are high paraffin base which causes deposits to form.
You don't want that in your engine. Only exception is Wal-mart store brand oil which I believe is Quaker State (re-packaged). If you opt for a synthetic, it's not a bad choice and is cheaper.
Make sure you use a good quality filter. The filter is what keeps the oil clean and useful during its lifespan.
One note... If there is any tapping or knocking inside the engine, that is caused by internal bearing wear and should be corrected immediately. No oil can compensate for internal pressure loss and if caught early, can be repaired. (otherwise, later, engine will need to come out and be overhauled or replaced.)
Any pressure problems can be verified by installing an external mechanical gauge on the engine. That is the only way to know exactly what is going on with any degree of accuracy. (dash gauge is electro-mechanical).
good luck

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