To remove the lower oil pan, first raise the vehicle and support it securely on jackstands, then remove the under-vehicle splash shield and drain the engine oil. Loosen the lower oil pan bolts in a crisscross pattern and remove them. Use a plastic-face hammer to bump the side of the oil pan to break it loose; if that doesn't work, tap a putty knife or other thin tool between the upper and lower oil pans to remove the lower oil pan. Clean all remnants of RTV sealant from the sealing surfaces and wipe them with lacquer thinner to remove traces of oil. Check the lower steel oil pan flange for distortion, particularly around the bolt holes, and flatten it if necessary. Apply a bead of RTV sealant around the steel oil pan flange and install the steel oil pan, tightening the fasteners in several steps in a crisscross pattern to the specified torque. The remainder of the installation follows the reverse order of removal. For the upper oil pan, the engine must be removed from the vehicle. Begin by removing the subframe and the rear cover from the upper oil pan, then remove the four bolts attaching the upper oil pan to the transaxle and the upper oil pan bolts in reverse of the tightening sequence. Use a prying tool to break the oil pan loose and remove it, then take out the two O-rings from the block and the oil pump housing, along with the gaskets from the front timing cover and rear seal retainer. For installation, scrape off all traces of old gasket material and sealant from the upper aluminum section of the oil pan, the lower steel pan, and the engine block, cleaning the mating surfaces with brake system cleaner while avoiding scratches. Ensure the threaded bolt holes are clean, apply RTV sealant to the ends of the timing chain cover gasket and rear oil seal retainer gasket, and position the gaskets on the oil pan. Apply RTV sealant around the upper aluminum oil pan flange and install new O-rings in the engine block and oil pump body. Carefully position the upper aluminum section of the oil pan on the engine block, install the bolts, and tighten them in the recommended sequence in three or four steps to the specified torque. Finally, install the transaxle mounting bolts, ensuring to install a new oil filter and wait at least 30 minutes after applying the silicone sealer before adding oil.