Four quarts is not normal. I would expect to see black soot inside the tail pipe if it's burning it. To go through that much oil, you should be seeing a lot of blue smoke from the exhaust.
To put things in perspective, my daily driver is an old rusty trusty '88 Grand Caravan with 389,000 miles on the engine and it's never been rebuilt. I haven't removed the oil drain plug in over eight years! I have to add about one quart of oil every 1,000 miles. If I forget, it's not at all uncommon for the valve train to start rattling and it takes three quarts to fill it up. It only holds 4.5 quarts so you can see I'm almost running it out of oil completely. I replace the filter about once every other year.
By adding so much oil, I'm getting the full treatment of additives such as seal conditioners, detergents, and anti-foaming agents. I rely on the leakage to remove the sludge and dirt. Mostly highway miles helps in that regard. As I told my students, this is not neglect; it's abuse, but it shows what these engines are capable of. I would not do this to any of my other cars, but with all their computers, I wouldn't trust them any further than I'm willing to walk back home. My '88 has been on three cross-country trips in the last three years. It refuses to break down. It just recently started leaking from the oil pressure sending unit. Other than that, there hasn't been an external leak in over five years. All my oil loss has been from burning it past the piston rings. I can occasionally see a puff of light blue smoke from the tail pipe. I'm sure there's more but I just can't see it while driving.
Start by looking under your engine for signs of wetness. To burn a quart of oil in 1,000 miles, there should be some sign at the tail pipe. It's common on a lot of engines for leaking oil to pool in hidden spots when the engine is stopped, then blow off on the highway when you start driving. Evidence of that will show up as wetness under the floor working its way toward the back. The engine will also be wet from the source of the leak and below it, but it might not leave a spot on the ground. Of course if there is a spot on the ground where you park, it's obvious there is an external leak that needs to be located.
Some of the more common causes of a leak are that oil pressure sending unit at the middle, front of the engine, and if you have the 3.0L engine, the valve cover gaskets can leak. They are reusable rubber gaskets. All that is required is to tighten the two bolts in the middle of each valve cover a little. Don't over-tighten them because that will distort the covers. One turn on the bolts is plenty. Camshaft seals can leak too. Those can be a little tricky to locate because covers have to be removed. That's where the dye is useful.
Front and rear crankshaft seals can leak, but that is very rare. If the rear one leaks, the oil will drip from the front of the transmission. The rest of the engine will be dry. If the front one leaks on the 3.0L, it can be thrown around by the timing belt and make it look like the leak is up higher. With either engine, the wetness will be on the passenger side of the engine. Oil pan gaskets have been known to leak also on both engines. Cleaning and resealing them is not a real big job. The oil will run all the way around on all four sides of the pan's lip, but the clue is there won't be much wetness above the lip.
Tuesday, August 23rd, 2011 AT 2:38 AM