New member and looking for advise.. I have a 04 Avalanche with 100k miles. Oil pressure dropped to 20 at idle and 40 at 3k rpm. Took it in to AAMCO and they replaced the oil sending unit, tune up, injection cleaning, spark plags, and pulled the oil pan to clean the screens...... Oil pressure went up 30 at idle and 50 at 3k rpm..... 4 days later the oil pressure dropped to 5 at idle when warm.... 15 when cold..... 20 at 3k rpm..... now there is a constant ticking sound in the engine.... Dealer says replace the engine for $7k but I think it may be the oil pump.... Anyone have any suggestions ?

 

Had an old ford truck( yeah I know...) same thing with it. It was gunked up inside so bought some of the best engine flush I could find and put it in. I let it run about 15 minutes drained it out, filled up the crankcase again with oil drained it out after 15 min. drained it out filled it up again and drove it. The pressure did improve but not substancially, about 35 to 40 on the road. I drove that truck for years and gave it to my son and then he drove it for a while.