I took apart my 3.1 a few months ago after 3 owners and 160K of hard abuse. The thing looked fine. No deposits, no strange bearing wear. I used the cheapest oil I could find and a purolator pure one filter every 4-5K miles. When I first had the engine, I used to use STP oil treatment but I don't think that does anything and would not buy stuff like that again. I also used rislone a few times when I thought I had noisy lifters. It was an exhaust leak actually. Just use oil.

CHRIS
98 Amigo, 92 Pup

need a pickup 1st gen fuel level sender