OIL and WATER !!

Usually the long bolts break because the two different metals, the bolt being steel and the cover aluminum react and cause corrosion along the length of the bolt over time and when you try and remove the bolts one will break. After you get the cover off there will be a lot of the bolt left to work with and I've always been able to remove them without to much trouble. On the oil leak i have also found the plate behind the oil filter can warp and cause a leak. it is held on by the center bolt that the filter screws onto.