i would change your plugs and then recheck timing and if plugs run hot for to some time the electroids will go bad so change them or your gonna wanna pull your hair out idk about that thin of oil 0-20w or 0-40 on older motors not that great sounds messed up but for examp i ran that in my 96 subaru and i did not like the sound of the motor if your gonna run syn like mobil 1 or ams oil or royal purple u might go as low as 5-20 but keep this in mind with a thicker oil will boost ur oil pressure theres alot of things to know about oils and brands not saying i know it all but i a GOOD amount thats why i run 10-40 syn in my rides and in warm outside temps 20-50 syns if ur gonna run it hard u might wanna be around there
