How to Replace an Oil Pan Gasket in a 98 Cadillacby Brett Johnson; Updated November 07, 2017
Items you will need
New oil pan gasket
4 to 6 qts. of 10/30 weight oil
Oil pan gaskets wear out over time and begin leaking at the rim of the oil pan. Sometimes simply tightening the mounting bolts will fix the problem, but in most cases, you should replace the gasket. This repair does require extra safety precautions, since you carry out the work under the vehicle. Replacement gaskets are widely available over the Internet and most auto-parts retailers will have replacements in stock.
Park your Cadillac on a level surface and set the parking brake. Brace the rear wheels using the wheel chocks for added safety. Raise the front end using the floor jack and place the jack stands securely under the frame and lower the car onto the stands.
Raise the hood, disconnect both battery cables for added safety and take off the oil fill cap to relieve the oil pressure.
Disconnect the exhaust manifold pipe (crossover pipe) from the cylinder engine block using a socket wrench. The crossover pipe is located on the right side when facing the engine. This pipe runs under the vehicle and crosses over at the oil pan and connects to the other exhaust tailpipe. Disconnecting this pipe will give you some space in which to remove the oil pan.
Put on your safety glasses and slide under the car on your back. Place the oil-recycling container under the oil drain plug. Remove the drain plug using a socket wrench, being careful not to drop the plug into the oil container. Completely drain out the oil and put the plug back in.
Remove all of the oil pan mounting bolts using a socket wrench, then gently tap the pan with a hammer to break the seal. Detach the oil level sensor plug attached to the oil pan. Scrape off the old gasket on the pan and engine block using a razor.
Apply a thin layer of oil onto the rim of the oil pan using your finger to hold the gasket in place. Place the new gasket on the oil pan and make sure that the mounting bolt holes are properly aligned.
Hold the oil pan against the engine block and screw in several mounting bolts by hand to hold it in place. Put in the remaining mounting bolts by hand and tighten them all using the socket wrench in a crisscross pattern. Clean off the excess oil on the pan so you can see if it leaks.
Reconnect the exhaust manifold pipe (crossover pipe) to the cylinder engine block.
Raise the car again using the floor jack and safely remove the jack stands. Reconnect the battery cables and slowly pour in 4 qts. of new oil and allow it settle before adding any more. Check the oil level on the dipstick and add more oil as needed. Start the engine, let it idle for several minutes and inspect the oil pan for leaks. Turn off the engine and check the oil level again.
Properly dispose of the used oil through a certified recycling facility. Most auto-parts retailers will accept used oil if delivered in a proper recycling container.
Do not to over-tighten the oil pan bolts. This will create a void and cause another leak. Only perform this repair when the engine has cooled, to prevent being burned by the exhaust.