i bought a new 78 ford 150 in fall of 77. used oil from the start and had bad piston slap. so after 7 qts of oil and complaints to dealer. they said bring it in and we will change oil and filter. they said call us after you drive 2000 more miles. i had their service manager put that in writing and he signed it. 4 days later and abit over 500 miles i called them. told them to send tow truck as truck had thrown a rod thru block. they put a new engine in it. the other one was like i had told them from jump street. no rings on any of the pistons!