After getting my oil changed because the oil light started going on I took it to a cadilac repair center.( i just bought the car off a car lot and this happened.) I knew the history of the car it had the motor rebuilt 25,000 ago and had 140000on odometer. After I picked it up the mechanic said he put a lighter oil in cause the light would come on at idle. Then next day it started popping through carborator. Took it to another mechanic he said a bad valve or bad lob on cam. Should I try putting heavier oil in or replace the engine. Whats my best choice or is there a fix that you know of?
Thanks for any help.

Need a little more info. what year and model ht4100 or 4.1 v6 Year can important when dealing HT4100 as far what can be done,but 4100 are hard on cams, flat lobs and worn out distributor gears are common. Carbon build up is also an issue.Hope it helps