Just wanted to share my experience on our 2005 Suburban LT 4x4 5.3L engine oil pressure problems. Actually up to about 2 months ago pressure had been pretty normal running 30ps at idle and 45 psi at normal driving speeds. Its kinda funny but just a coincidence though I believe that I noticed it after my wife took it to Valvoline Quick Lube place. This Suburban has seen alot of starts and city driving besides highway miles.
I've always changed the oil and filter every 3000 miles in the past but she "tried to help me out this time" I had been using 10W-30 high mileage Castrol GTX for quite some time with an AC/Delco PF46 filter. They used 5W-30 Valvoline with their filter. Did the tech do something wrong? Hell who knows but I replaced the oil and filter the next week as oil pressure was acting weird. It seemed to return to normal and I even had my mechanic replace the oil psi sending unit. (2005 does not have a screen). Everything seemed in normal range again but she drives it not me so who knows.
Well 4 weeks ago the 4L60 tranny lost 3 and 4th gear clutches suddenly after she got off the highway or tranny was starting to slip and she didn't realize it. So my mechanic put a rebuilt tranny in it for $1800 and it works great. The oil pressure issue was still bothering me as it started to get worse with idle oil pressure dropping below 20 psi and setting off low oil pressure message. I asked her about it and she said it had been doing it off and on for about 2 weeks. She could hear lifters ticking when this occured and engine was sounding funny. I work out of town so I'm always not around to jump right on an issue but told her to let me know always.
Well I've read the many oil pressure & usage problem of the 5.3 LS1 GM engines and knew I could try the oil pump and pickup tube O-ring replacement first. But I asked myself the question what if the engine has some internal issues and with 160,xxx miles how much more life will I get out of it without further engine problems. Oil consumption has been 1 qt plus between changes for a long time so not real bad there. It has the original crappy design left side valve cover on it still. My mechanic drove it and we talked long and hard about it. I told him I wanted to keep the vehicle another 4 yrs at least as it has no rust and is in excellent mechanical condition other than the motor. We only paid $18,700 cash for a 3 yr old Suburban with 33,000 miles cause nobody wanted them when gas was $3.85/gallon. This belonged to a doctor's wife and it came loaded with options. (sunroof, DVD player,heated seats, etc)
We decided that the Jasper Engines 5.3L rebuilt long block with oil pan & timing cover for $2500 was the best way to go for her to have a reliable vehicle still. Only breakdown she ever had was the transmission. He's an authorized installer and they have a 3yr/100,000 warranty on the motor. On their website they talk about how they correct all the "issues" with the 5.3 LS1 engines during the rebuild process. So Monday it will be getting the motor installed and I'll give a follow up on how things turned out in a few weeks. It will be getting a new water pump, radiator hoses, belts, plugs, starter and new design left side valve cover too. I figure total cost around $4000. This will put my overall maintenance cost to $11000 for 8yrs of ownership. Still the total cost without gas costs at $29700 is still way below the $50000-$60000 of what a new one would have cost if we would have purchased new.