Ok i am fast approaching my next oil change and have a question. My trailblazer will have 52000 miles on it when i get home so i am wondering can i safely switch over to synthetic oil like amsoil at this point? The understanding i have about synthetics is that they should not be used on higher mileage engines due to the threat of oil leaks. Since i am used to metric up here and am still getting used to the american cluster in the trailblazer i need to ask what mileage intervals should i be changing oil at? I normally changed at around 3500-4000 kms with my older vehicles so im not sure what i should be using for intervals on my american trailblazer. Thanks in advance guys!