i use carquest 5w30 full synthetic oil. carquest is the same oil as valvoline. i got 75k on my 97

 

You cant go wrongwith Rolay Purple 5W-30 yes its going to cost you 6 or 7 bucks a quart but well worth the money i think.The TA just turned97,000 and still running strong.For regular oil castrol 5w-30 gave me a 89 V6 firebird thats never had the vavle covers off 230,000 And still kicking plus a 85 pick up that my grand pop handed down to me before he died that had 160,000with 305.Also never had the valve covers off.

 

mobil one full synthetic

 

i also use royal purple 10w 30 in the summer and 5w 30 in the winter and colder times.

 

WHere is the oil leaking from on the intake?? Why don't you clean it off and hit it with some high temp silicone?

 

I use Amsoil Series 2000 0-30 racing oil. Runs great in my 94 Z28 and my 95 Z28.