Dear Tom and Ray:
OK, this is going to be a bit of a long story — sorry. As a college graduation present, my father got me a used 2004 Mercury Sable with 189,938 miles on it. When he gave it to me, he said it had only a small oil leak, but that leak turned out to be coming from the oil pan, and it's more than a small leak. I have to fill it every three to four weeks, which is getting expensive. So I took it to a friend who is a mechanic, and he discovered that my oil pan is welded in place, not screwed on, like it should be. So we are at a loss as to how to remove it and replace it without things getting really expensive. My friend thinks we should drop the engine and try it that way. What do you think we should do? — Kylee
Ray: I'd say fill it with oil every three to four weeks and start applying for sales jobs, because they sometimes come with company cars.
Tom: You're in a lousy situation here, Kylee. Your oil pan is leaking, most likely because the gasket failed. Normally, that's a pain in the neck, but not a horrible repair. But I'm guessing that at some point in this car's recent past, someone broke off the bolts that attach the oil pan to the engine block.
Ray: That would explain why they welded it back in place. The proper solution would have been to drill out the broken bolts and tap new holes, and use slightly bigger bolts to reattach the pan. But that's a big and treacherous job, so they took the easy way out.
Tom: Your friend is suggesting that you do that job now, because it requires pulling out the engine.
Ray: But before you go to that length for a car with close to 200,000 miles on it, try a simpler solution. Start by thoroughly cleaning the area where the oil pan meets the engine block. Use a good solvent, like Brake Kleen. You can reach most of the oil pan from underneath the car with minimal removal of nearby parts.
Tom: Once it's been thoroughly cleaned, remove any rubber gasket material that's hanging out, and then lay a bead of silicone caulk on the seam. There's a type of silicone caulk that's impervious to oil, which you can get at parts stores, and that's the stuff you want.
Ray: I would start by putting a thin layer of the caulk where the pan meets the block, and let it dry overnight. Then apply another layer the next day. Even if it doesn't completely stop the oil leak, it may slow it down.
Tom: That'll give you time to shop around for some really cheap cases of oil. Good luck, Kylee.
(Car Talk is a nationally syndicated column by automotive experts (and brothers) Tom and Ray Magliozzi. Write to them at the Car Talk website.)