I have not used penzoil ultra, but have used castrol edge. This motor oil and mobil one still have zinc in them which acts as an additional barrier and coating for your internals. You can change it every 15k or 1 year which ever is first. I am using a mobil one filter with a 99.9 first time filtration and 98% thereafter. The oil seems to be more quiet, but am a little sceptical about the whole 15k mile thing. I will let you know in another 7k what the oil looks like.