1991 Jeep XJ oil change

[captainofiron]

Originally Posted By: jeepman3071


If you have replaced the rear main twice and it hasn't helped I would look at your valve cover gasket. The valve cover gasket is known to leak down the back of the engine and look like a rear main seal leak, its also what usually coats the engine in oil when it leaks.


Yea I have replaced the valve cover gasket a couple times, the cork one just wasnt cutting it, so last time I invested in the "expensive" blue rubber felpro one, and that seemed to help.

Actually the biggest help to stop the leaking was when I built a catch can that I put in between the valve cover to the intake elbow

 

[captainofiron]

After looking around locally, Im going to go with the Rotella 15W40 (since its really all I could find)

plus the Jeep most of the time is in my garage (which is fully insulated) so I think the winter cold start ups wont be too bad anymore

 

[84zmyfavorite]

Yes the FelPro 1 piece gaskets are Awesome. My Gold 2000s 4.0 is getting one(I already have it, Awaiting) when Her ReBUILD is done. No more Mr.0331 Cylinder head, I have spent over 24 hours Porting&Polishing a 92' head that Shes gonna need with that 258 Crank. 4.5Liter with only a Light Hone. Currently I have 5 Cherokees with the 4.0, Have owned 13 total over the past 10 years, and worked on many other 4.0s(and 232s,258s,304s,360s,2.5s) and this 2000s badly neglected 213,202 mile 4.0 with cracked 0331 head and all, Has the least cylinder bore wear of any 4.0 I have seen. CrossHatching is mostly All still there, like as if it had 30,000 miles. The dual collectors running by this 4.0s oil pan gasket did Cook its Original Felpro 1 piece gasket pretty good. Not like a 87 thru 99s single collector. Hmmm, more exhaust pipe surface running close by the oil pan. Great idea, like the Blasted collector bolt stoppers on those cast (2000 thru 2006)manifolds.

 

[84zmyfavorite]

Oh, Oil,...I would run 6 quarts of German Castrol, Castrol Syntec EDGE 0w-30 in that 1991 Jeep 4.0 ifn it were mine. After replacing at that leaking oil filter adaptor o-ring, or leaking rear main. Oh wait it is leaking all over the engine bay. Valve cover gasket with New CCV and PCV 90s, New 1 Piece $19.99 FelPro oil pan gasket(Auto, no VatoZone), Front Main oil seal $9.99, and maby also Head Gasket. Could be any one of those or all of them.