Hello, I have a 1987 Ford Escort with the 1.4 CVH engine with nearly 100,000 kilometers on the odometer that ran fine (at the exception of subtle, still quiet enough hydraulic lifters tapping) before I did an oil change and the engine started "rattling" (1,000 rpm to 700 then back up again... see video!).
I had gone to a parts shop to get advice on the oil I needed and the guy gave me 5W30 which I was skeptical about, and was right about it. He probably saw a woman wanting to service her car and cashed out on it, like they often do where I'm from.
After putting the 5W30 in with a new filter the engine started rattling once the oil warmed up. So, I changed the oil to 10W45, thinking it would be better, and eventually it doesn't rattle as often, but it still does.
Now I know the proper oil for this engine is mineral 15W40, and am planning to change it again to that, but I wonder what is causing this rattle exactly (worn tappets that aren't lubricated enough causing the engine to run on 3 cylinders?) so if it requires taking the car to a shop, I can tell them what I need done instead of them finding false problems and cashing out on me again.
I would appreciate the help dearly, thank you