PYB conventional will protect well enough for 4,000 miles ... Of course PPP synthetic will protect better , longer at temp extremes and provide better cleaning ability where as with PYB conventional you might get some light varnish after a number of miles (light varnish won't hurt anything) . I dare say the few times I ran PYB conventional my engine sounded better than it did running any synthetic oil . PYB conventional is fine for 4,000 miles / 4 months where as I run PPP synthetic out to 6,000 miles / 6 months before changing .