A: You have to check the oil's ratings to see if it qualifies for gas and diesel. I run Chevron Delo 400 15W40 in my Jeeps and haven't had a wear related failure yet. (unless the motor was run OUT of oil, like my '83 Cherokee when the oil sender blew off and I drove 30 miles w/o oil) From: "Jay" <jciampi@xxxxxxxx> To: "AMC LIST" <mail@xxxxxxxxxxxx> Subject: Motor oil for older engines Date: Sat, 6 Nov 2004 07:03:21 -0500 I was reading a "tech Tip" in a Nash Club regional newsletter the other day stating that we, who own cars with pre-cat.converter engines, should use Diesel motor oil as it still contains ZINC for lubricating cam lobes, valves,etc. Modern engine with Cats don't need Zinc as they use hardened parts and Zinc will totally ruin a Cat. Modern gasoline engine motor oils do NOT contain any Zinc for that reason. Anyone out there that confirms that we need Zinc or can refute the statement that Zinc isn't necessary? I have never looked at a bottle/can of diesel motor oil to what it contains, so I have no idea if this is a genuine concern for older engines or not. if your engine has been overhauled with modern components, Zinc would not be necessary for your engine lubrication. Jay in FL.