Castrol 10W 30 on my 86 mustang GT good for 300,000 miles. Yes 300000 miles. I run Mobil one in my other cars but the cobra and the 86 get the castrol. cheap and effective. I don't buy into engine
oil additives nonsense. JMO P.S. My dad helped me buy the mustang as a graducation gift for myself from college in 1986 best damn car I have ever owned.
Oil changed religiously at 3000 miles.
later
Dennis Kelley