Hello fellow Subaru devotees. I've been searching these boards and trying to find an answer to why I woke up this morning and my 1992 Subaru Loyale 235K had a terrible lifter noise. It was loud and on the passenger bank of cylinders. I read about how these stick and cures from using aftermarket thickners, Risilone, Marvel Mystery Oil, etc etc. I also read that a piece of carbon or built up sludge could cause this to happen. I replaced the engine on this car at 215K, with a Japanese pulled engine (they said about 30K on it). Anyway so the engine probably only has 50-55K on it and I change the oil every 3K religiously. I don't deserve this sticky lifter. Anyway some old timers (probably in their 30's) recommended trying sea foam, or ATF fluid. ATF is a high detergent lubricant from what I read, and it can help clean up sludge and help unstick a sticky lifter. My oil pressure was good so I didn't opt for the oil pump reseal yet. I was about 1/2 way through this oil change period, so I drained a little oil and topped off with a quart of ATF fluid. I drove it about 30 miles to get it warmed up a bit, the noise ceased at about 10 miles. Yes, it CEASED. You don't want to drive too long with ATF in it, so I'll change the oil now while it's hot. I'm going to mobile 1 synthetic, because I got a good deal on it at Costco. I had been using Chevron 10-30, also a good deal at Costco, but a couple of months ago I pulled the valve cover off my Toyota Land Tank and was more than surprised at how clean the synthetic oil kept the engine. NO sludge period. The cam and valve train were bright and spotless other than a gold tinge that mobile 1 gives to the engine components. It was really clean so I'm going to refill with that. I would highly recomend you try this ATF trick for a while to see if it helps with your lifter. I could hear it was only on one side. If your oil pump goes out, it is not a tick. It's a loud rattle and you will show zero oil pressure or almost zero. That's how my first engine went. From what I know now, I would have just replaced, or resealed the pump. These engine last forever. Anyway anyone who reads this forum deserves and atta boy. Can you imagine the moolaa I would've shelled out at the repair station for a sticky lifter? I'm not even going to guess, but people who don't know about or pay attention to these forums give our automotive economy a big boost in the pocket every day. Ya'all take care and have a great weekend.