“This is a really good article by AMSOIL on 5 myths of motor oil that are not true!
-When motor oil turns black it must be changed
-You must change oil every 3000 miles
-You can’t mix synthetic and conventional motor oil
-Once you switch to synthetic you can’t go back
-Synthetic oil causes engines to leak oil
Also, there is a good video with Gale Banks on “what’s in synthetic motor oil!”