very sudden increase in oil leak!!

This morning was pretty much our 1st real cold morning here in southern NH and my Cherokee did not turn over very fast, just barely caught. So I'm driving into work thinking it may be time for a new battery...
I get to work and back it into a spot just in case it decides not to start, when I notice a great deal of smoke coming out from under my Jeep
So I get out and look underneath and I can see the puddle growing as I watch, everything is very wet underneath, but the main puddle is coming from the usual (after searching here) right rear portion of the motor.
Like most XJ's my engine has always leaked a little, sometimes leaving a little dolop of oil sometimes nothing at all, I mean maybe a quart every 2-3 months was all it took to keep it full, which I don't think is bad for a motor with 225,000 on it.
I read and realize all of the spots that could be leaking, but the sudden drastic change has me puzzled? Thoughts? I haven't looked at the air filter yet to see if my crank pressure had built up. Looking at the right side of the motor, aournd the filter adapter, pressure sender and dip stick tube don't look any wetter than usual (yes my engine is greasy and has been). It just seems like such a drastic change to be the rear main seal, wouldn't that slowly worsen over time? I'll do what I have to out of necessity, but it's cold and I don't have a garage....
Thanks,
Scott

Anytime mine starts seriously leaking, I find the crankcase vent plugged. The small one from the valve cover to the intake. Also check the grommet, were the line plugs into the valve cover have found the hole in the grommet plugged.
The plugged vent usually isn´t the cause of the leak, that´s usually a gasket or seal, but the pressure in the crankcase, makes it worse.
If it´s cold be carefull with the plastic vent line, they are brittle anyway when old and worse in cold weather.

I'd do an oil change and put in a synthetic, see if that helps, reason being that when organic oil is cold it's thick and does not flow so well, synthetic pretty much pours out of the bottle the same whether it's 80 outside or -20... does the same thing in the engine. I used to run mobil-1 in my trooper and got used to the way it started on very cold mornings, it needed an oil change so I took it across the street from work for an oil change, they charged me $50 for Mobil-1 oil change. Got out of work, paid for it, fired it up and as soon as it turned over I KNEW they had put organic in. Stormed back in and demanded they show me the empty bottles, which they did not have. Passed the word at work to everyone, being the network and systems admin I warned all 600+ employees about the rip off... Sorry for the digression.
Also if you have any moisture in the oil from short trips and not allowing it to 'cook off' you could actually be getting some ice in there..
Consider that a mechanical oil pump can actually pump some prett thick stuff....but the filter may not be able to pass it thru...

Thanks, I have used Mobil 1 since I bought it 60,000 miles ago, so I was a little surprised it turned over slowly, but I've never changed the battery in the 3.5 years I've owned it and I need a starter because it turns well but the wire going from the solenoid to the motor needs to be "wiggled" once in a while to get it to turn over at all. I have just been avoiding replacing the starter for something as simple as a bad connection, but this could have added to the slow turn as well. When I got to work I shut it off and it restarted normally other than the oil everywhere!
It seems weird that the pressure could build up that bad because I have replaced all of the plastic hose to the aircleaner with a rubber hose and a copper bend. I run it this way for months with no problem. My air cleaner does get some oil on it, but again, it really isn't that bad and I replace the air filter about once a year. I guess I'm hoping the little vacuum hose was frozen and caused this, God knows I really don't want to put a rear seal in it now!

I know this is kind off of a dumb suggestion, but try tightening the oil filter. My uncles XJ started doing that and I noticed it was coming from the area around the filter, but it did not look like it was coming from the filter. It was our first cold night and he had just changed the oil in warm weather. When he installed the filter it was nice and snug, but the first cold night caused the rubber seal on the oil filter to shrink and allow leakage when it ran. I tightened it up, and no more leaks. Just a suggestion. Good Luck.

90red

Thanks, I went out at lunch prepared for the worst but hoping for the best! I didn't feel like prying the air filter cover off, so I disconnected the hose I had installed and got a couple of oz. of water! It was clear, so I have no reason to believe it wasn't condensation. In the last couple of weeks we've had some torential downpours! I'm thinking that maybe it was blocked and frozen, maybe the other small hose was frozen too? Hard to believe that the pressure wouldn't have blown the hose off though, it wasn't really on there very tight. So I'm still open to things to look at (I will check the tightness of my filter next trip outside thanks).
I drove it around and other than the oil that was already there still dripping, it seemed fine. I doubt the whole event amounted to more than a few ounces but it sure does make a mess, at 1st glance you think you've gone through all your oil, but then check it and find out it was less than 1/2 quart (not sure how much I was down, hadn't checked the oil in a couple of weeks)!

I have had K&N oil filters loosen up after an oil change, had it happen twice a year + ago, figured it was the gasket they used, Mobil-1 filters went on sale so I stocked up on them, then K&N went on sale when I was running low on the M-1 filters so I went that way and stocked up and they were fine. Then the last time I changed the oil on the wifes olds the K&N had loosened up and spun off freely with my hand when I went to change the oil. The were all tightened correctly, I use the socket type wrench that goes on a 3/8" drive to remove and install them, I also do the 'fire it up and check for leaks for 10 min' exercise.