I changed my oil this weekend and I put in royal purple 10w30 which i normally use conventional. It developed a terrible oil leak. Bad enough that when I drive down the road theres a trail. It seems to be my rear main but I just replaced it a little less than a year ago and i havent driven the car in 3 months. Is there anything I can put into the oil to soften up the seals and make them seal better w/o actually contradicting switching to a synthetic oil?