'91 Explorer Losing Oil | Ford Explorer Forums - Serious Explorations

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'91 Explorer Losing Oil


Active Member
April 9, 2010
Reaction score
City, State
Wasilla, Alaska
Year, Model & Trim Level
1991 Explorer Eddie Bauer
Hello again,
Trying to figure out why my 91 Eddie Bauer is losing oil. Every 300 miles or so my oil light comes on which means i need to add a quart. Everything on the motor has been machined and reworked and it runs great now. My brother suggested a new PCV valve so that was replaced several times now.

There is no oil marks on my parking spot.....no drip marks anywhere behind the valve covers.

This has turned into a real head scratcher.

Any help or ideas would be greatly appreciated :)

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Also on the oil type, being in Alaska where it can reach -50F i have been told i should be running 5W30 full synthetic. Is this correct?

This has been happening to me every ≈600 miles ever since a complete rebuild ≈15,000 miles ago. I tried the pcv replacement too, unsuccessful.
No oil leaks, no discernable white/blue smoke from tail pipe. No coolant leaks. Just oil dissappearing. I also had a ping/predetonation/ when accellerating uphills. There are a few of posts here that attribute it to lower intake manifold bolts that require re-torquing. A #5 spark plug that is extra fuzzy with white deposit has been called out to be more evidence of this. My #5 was infact extra fuzzy, so I recently disassembled down to the lower, and 2 of the bolts were in fact not near torque spec. I retorqued, (did not replace the lower to block gasket, did replace all the other gaskets to get to the lower) and reassembled. Have not driven enough to know if it solved the problem. Will see soon. If it didn't work, then I suspect the replacement head I have may have warped, as that is the major change to the engine in the rebuild that I think could explain this.

there are a couple other posts too. don't have them bookmarked.

So you are losing a full quart of oil anywhere from 300-600 miles with no marks on the ground and no smoke from exhaust? I am curious about this, it has to go someplace! lol a quart of oil is a large amount of oil to be just going away. Drain plug and filter tight no oil leaking around the filter? I can check my owners manual for you on cold weather oil but i am pretty sure that is correct oil aside from it should be synthetic blend oil, motorcraft 5W30 is a blend. Something curious about oil weight, at least on my rig is on engine bay it says use 10W30 but owners manual says 5W30, figure that one out! I hope you find somthing! let us know!

So you are losing a full quart of oil anywhere from 300-600 miles with no marks on the ground and no smoke from exhaust?
Not intending to hijack thread. My case is this: 1 quart, every 600 miles. No leaks. Not a drop. No smoke, or not enough to be obvious. OP probably has same or very similar cause, just consuming ≈2x the rate.

I'm in northern MN, I ran 5W-30 full synthetic, -30 degrees and lower, it worked great year-round for many years. Minor ping on engine loading is normal, it is even mentioned in the owner's manual as normal behavior.

If you have high confidence it is not leaking, it is being burned... a leak-down test will help diagnose.

I agree with every part of what 777 said. Minor non constant ping is normal 5W-30 will be fine i always only stating that the motor craft is a blend (at least what is sold here is) and if you really can not find a leak do a compression test, although with that much loss id like to think it would be pretty gutless/miss something. Or you have someone playing a twisted joke on you.