i changed the oil 2 1/2 months ago, i plan to change it this weekend. i use 5-30 castrol regular oil, not the synthetic one, would it make a difference if i add synthetic oil, that stuff is pretty expensive and i read somewhere that if it has not been used in a long time it i snot recommended, due to its thinness and might leak more from the gaskets on the engine. Especially my engine is almost 200k.
Change the viscosity? You mean the type of grade oil I put in or...
I live in Arizona and in the summer time I use the 20-50.
Changing the type of oil grade like that does it harm the engine?