I have a 92 camry with 130k mi. It runs great and I want to keep it running as long as I can. So I'm considering switching to Synthetic oil. Walmart brand beacause its about half the price of mobil. I heard that some older eninge seals can't handle synthetic oil and will bread down and leak. is this true for a '92 Camry 4cyl engine? Any comments on my idea to switch or the leaking?