Hugh, the diesel oil serves the same basic purpose as the Marvel Mystery oil. Whether you want to clean the engine out by soaking it in diesel or marvel mystery oil is subject to debate. Without a doubt it is a good idea to drop the pan, change the oil and clean the oil pump pickup screen. Turning the car over with the plugs out is a good idea. A better idea is to prime the car using a drill and one of those tools that fit in the distributor drive. _________________________________________________________________ FREE pop-up blocking with the new MSN Toolbar � get it now! http://toolbar.msn.com/go/onm00200415ave/direct/01/