I hope the aluminum foil is nothing more than just a oil jug seal. It didn't appear to have any glue or otherwise on it, so i wonder if that melted off from the heat of the oil, or if this came from another source. Either way, the concern remains about the sludge. When a shop ran my car to see the type of oil, they claimed that it could take either synthetic or conventional. I assume that at least one owner decided to put the cheapest garbage in the poor thing, because the sludge is ridiculous. I guess if i didn't know I would probably buy the cheapest stuff too....
So far I made an attachment for my shop vac so i could scrape and suck the sludge and varnish out to get the big deposits. so far the head looks better. That said I have taken apart Briggs and Stratton engines from 1940 with less sludge and varnish buildup. Really looking for a chemical remedy at this point.
May give the kerosene a try soon, but first i am trying some detergent. My plan is to pop off the oil pan and get the big deposits that i assume are there. Then I will fill her up with cheap synthetic and run the oil detergent for a few hundred, then add a motor oil flush liquid that is marketed as being something you run right before an oil change to break up the goo before doing the change. Once it is all emptied out I will probably stick my inspection cam in there and see if any of the remaining sludge and varnish still stands. If it does, i will probably give her a fill up of kerosene and cross my fingers that a spark doesn't happen in my crank case in the few minutes i will run her on it
After that point, if the poor bastard still has a lot, then that is how much it will have the rest of its (hopefully long) lifetime. Going full synthetic at that point.
Additionally I took valve clearance measurements while i was in there of course, but i cant seem to find a 2012 service manual, so i don't know how to adjust these and if they even need it. If anyone has a link to the service manual please let me know, I need to search within the forum too, as im sure I am not the first person to need it