oil ???

[wired1]

I ve been using amsoil 15w40 since i bought the truck, thats what the guy i bought it from was using. Iam having trouble getting more then 6k on an oil change. I even have a by pass filter. And i am using blackstone for oil reports.I think i am going to change oil mfg and was woundering what everybody uses for synthetic's?. Because i was told once you go synthetic you cant go back. thanks

[dieseldan2005]

why couldn't you go back to synthetic? I am gonna run rotella 5/40 syn on my next change and probably go back to conventional 15/40 in the summer. Lots of people do this. I have never heard of anyone havign problems from switching oils. as far as brands, i like rotella, but i have heard amsoil is pretty good stuff. None of it is very cheap though. My old boss always told me oil is cheaper than parts, so not to try and extend an oil change if it could cause premature engine damage.