I own a 1995 Saab 900 with a V6 and has about 140.000 miles. I recently the care 2 hours on the highway (65/70 mph) and it ran perferct. I stoppoed to obtain an oil change when I reached my destinationange before giving it to my son. Upon attempting to leave the facility the car began clattering like a diesel. The oil level was checked and it was oK. Any ideas on what could've happened? Is there a possibility the engine is damaged extensively? Is is possibile to replace the saab v6 with another v6 from a Catera or Saturn?

Thanks Much