Need help with my 1998 mustang
I just had an oil change in my 1998 v6 mustang.
The car has always had 5w30 since it was
manufactured and they put in 5w20. Before I notice
they changed the oil I started hearing a knocking
noise that comes and goes and a loud whistle
when I shut the car off. I got them to drain it and
put 5w30 back in but I am still hearing it just not as
loud.it didnt make these noises till they put the
5w20 in. Any idea on what this is or how to fix it?