My transmission leaks about 1 quart of oil per month and only when I turn off my car after drive. It will be parked and running and nothing, as soon I turn it off it starts dripping. Sometimes the spill is as wide as 5inches and sometimes it will be one tiny drop... and sometimes it won't leak for a week. :huh: . The tranny has about 70K miles. No slipping, shifts smooth , oil looks like new and I always make sure it's filled up to top. Could it be bad gasket?