Inconsistent oil usage Jeep 3.7

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Hi everyone. Been a long term reader/lurker on random stuff throughout the years but finally decided to join. I have an 05 Liberty with the 3.7 engine. It has 160k miles on it and I've always changed the oil every 3-4k since I got it when it was 2 years old. Past year or so, it has seemed to start using oil, sometimes a quart per 1000 miles. But not always. I know it has a leak coming from the front crank seal (I think). It leaks enough to coat the oil pan but never drips. Not sure if it's burning or leaking more oil, tail pipe is not oily at all and there isn't an oily film on the back of it like I experienced with a Hemi Durango that burned oil badly. I also use the Jeep for a weekly commute that's 150 miles each way, sees about 350 miles a week. I used Valvoline Maxlife for two OCIs last year (switched from regular dino to HM at about 145000 miles) and that helped a bit, then I am now using Castrol HM oil, both 5w30. Strange thing is, after the oil change (first 500-1000 miles of the OCI) it does't use hardly any oil. After the oil gets some miles on it, the usage increases quite a bit. I check the oil before each leg of the trip. PCV valve is new as well. I guess my two main questions are... 1. Is that common for the HM oils to break down like that? Would I be better served going to a straight dino oil as oppossed to the Semi-synthetics like the ML and the Castrol HM? 2. What is the best way to isolate between leakage and oil burning? Sorry for the long winded post, if anyone can direct me to previous threads that cover this that would be great!
 
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My daughter has the same car and as you probably already know, the valve cover gaskets notoriously leak on those engines. I talked to a Chrysler tech about these vehicles before I bought hers, he said they aren't bad, but they just leak everywhere. And he was right...behind the power steering pump, valve covers, rear pinion seal, tranny pan, tranny pump. As for the oil isage after 1,000 miles...I have the same problem with my own car, but it happens after 4,000 miles. Things to look for with oil usage is smoke - bluish smoke. If you see a puff of dark smart when you initially start the vehicle in the morning,mid suspect valve seals. And if you get a puff of smoke out of the tail pipe when you floor it....same deal, valve guides or valve seals.
 
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Go to a do-it-yourself car wash and get everything under there clean, really clean. Spray some degreaser carefully around the area for a couple of times before the car wash and stay away from the upper part of the engine compartment and away from expensive electrical stuff. Start checking the area frequently and isolate the problem. Then decide what to do about fixing it. Now you can determine what's left to do. This might just fix the problem or at least narrow it down to consumption vs a leak.
 

HoosierJeeper

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Good ideas guys! Yeah the valve cover gaskets seem to be an issue one these, especially the passenger side one. For the leak, I'm thinking that with as much highway driving as I do with it, it probably gets blown back before it can really drip. Plus the skid plates probably catch quite a bit. When I start it, I just see the standard steam coming out. Don't really see any blue but I'll pay better attention. Any thoughts about the oil choice? Or stay on course? Is the semi syn HM stuff exacerbating the issue?
 
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If there is a valve seal or ring issue, it can be inconsistent. Faster you drive, more revs, more oil gets past them. In the morning after sitting overnight have a helper start the engine and you watch the tailpipe. I'm guessing its valve seals
 
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You mentioned a new PCV valve, is it OE an aftermarket part? Aftermarket parts like PCV valves can be hit or miss at best. I learned that the hard way. I replaced a Ford PCV valve with a Purolator PCV valve as part of a tune up. All of a sudden I started using oil, switched back to a Motorcraft part oil burning stopped instantly. The same happened a few years later with a Fram PCV valve in another vehicle. I switched to OE and the oil use stopped. Lesson learned! You also mentioned an oil leak, I would fix that. While it might not be dripping it could be slinging oil while driving at speed and you're not really seeing how bad the leak is. I would address the obvious items first and work from there. One way to isolate between leakage and oil burning is to fix all leaks first.
 

HoosierJeeper

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The PCV is an aftermarket one. I thought if it rattled that meant good. I'll have to try a Mopar one. Easy starting point! Thanks
 
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It's about how ell the ball and seat fit. MFG tolerances, etc. OEM's are designed to pass smog testing. Others, maybe ... That's where I'd start. And go back to MaxLife HM as a test. Oil chemistry is not all the same. In some cases, the individual formula may make a difference... Once you have found one that works, stick to it smile
 
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