I tend to drive older European cars, mainly E28 and E30 BMW's and have always run either 15w40 Delo 400 or 20w50 Kendall GT-1 dino in them. I'm picking up a 96 SAAB 900s convertible tomorrow, 107xxx miles, 5 speed car. My research would indicate that this engine isn't the sludge-monster that some newer SAABs are, so can I sneak by with 15w40? Just for simplicity sake it would be nice. I tend to do 4k-5k OCI's with WIX filters...