Looking for some advice from fellow Ford guys.

Not really truck related but here goes.

I just picked up a 2001 Sable with the 3.0 DOHC engine. Car has only 50k miles. Guy I bought it from had just had the oil changed with an unknown synthetic at 45k. This engine is dry as a bone with zero leaks.

I change the oil to 5w20 Motorcraft with the correct FL820S filter. The one I took off was a no-name of the wrong size. Anyway, the day after I change the oil I take a 400 mile road trip. When I get home I notice a wet spot on the garage floor and jack it up and take a look. It appears about a cup or so had leaked out. Wiped it off and now it just gets slightly wet after short local trips. The leak is coming from the rear main I am fairly sure.

The road trip was at speeds averaging 75-80. I am going to replace the PCV valve this week thinking that it might be letting the crankcase build up some pressure. If this doesn't fix it I thought about trying some high mileage oil. Even with only 50k miles it is still a 15 year old car.

I just don't understand how this one oil change caused this or is unrelated. Any ideas for cause or a fix short of pulling the transmission?

 

I agree with changing the PCV valve, just in case its acting out & causing a crankcase over pressure condition. I also agree with trying a high mileage engine oil, to see if it can soften & reseal the rear main, or at least slow the leak.
Reports from around the web about Valvolene MaxLife High Mileage Semi-Synthetic are good for it slowing, or stopping leaks & it also meets GM Dexos spec. so It has to have a lower NOACK % evaporation & lower piston deposits than API SN.
It's NOACK is 10.8%, thus its base oil has to be of good quality, so if NOACK % evaporation is also a factor with your engine, perhaps give it consideration & let us know how it goes.

 

Well, I changed the PCV valve and all the associated rubber parts. After a several mile local trip it was dry as a bone. This is the same type of local trip that before had left a drop or 2 on the oil pan so it appears to have helped.

A road trip will be the next test but before that I think I will change to the HM oil just to have a better chance of this problem going away.

 

Ok, good feedback on changing the PCV valve having a positive effect on the rear main seal leak.
I agree that having a high mileage brew in the crankcase before & during the road trip is likely a good idea, as the road trip will get things warmed up, mixed & circulated real good. It might take a few weeks or months before the HM recipe has a chance to do all it can. Keep us posted on how it goes.

 

The old PCV valve did still rattle a little when I shook it. It was a very sluggish rattle compared to the new one. Who knows, it may have been sticking a little. Cheap part but installing it was not real easy. Not horrible, but not easy.

The old hose from the valve to the throttle body was coated in a fine mist of oil too. I didn't see any noticeable holes but the rubber had definitely seen better days. I wouldn't be surprised if the old hose wasn't collapsing under vacuum.

 

Just an update but with about 3k miles now on Mobil 1 High Mileage oil the underside has stayed bone dry.

For some reason I talked myself into the 5w30. My thinking was that this engine was designed with that viscosity. Well, my mileage dropped from around 27 average to 25. Cant wait to change it back to 5w20 and will stick with the Mobil 1 HM.

 

OK, good feed back on the oil weep/leak seeming to be fixed with the PCV valve replacement & switch to the Mobil-1 high mileage recipe crankcase lube.
With the old PCV valve being kinda sluggish inside, maybe its caused enough crank case over pressure back wash & oil mist fouled the MAF sensor some, causing it to be lazy in sensing & reporting intake air flow changes & is beginning to muck up fuel trim a little???
Hard to tell though with that little of a mpg change, as that small of a figure could come about with drive cycle, temperature, gasoline, or tire pressure changes!!!!
If you decide to try cleaning the MAF sensor, consider removing it so you can get to both sides & if just driven let it cool before spraying with the non-residual CRC MAF sensor spray. Be careful not to touch the sensor with the spray wand, let it dry & keep it squeaky clean when reinstalling. More thoughts for consideration.