I went to Carcomplaints.com and looked up info on the 2008 Suburban 5.3 liter engines. Excessive engine oil consumption leads the list of complaints for that year. Actually, 2007 was a new generation year for the vehicle and was even worse than the '08. I have a 2001 5.3 liter with 244,000 miles, but only add maybe a quart between oil changes and that's due to the front and rear seals leaking. All I can think to suggest is trying a high mileage oil instead of a full synthetic at this point. I am using a high mileage synthetic blend in my engine. I also use a Bosch oil filter with a check valve in it that helps keep the oil in the upper part of the engine where it needs to be. This helps with the engine knock that is typical with the earlier 5.3 liter engines. If I drive it today, it hardly makes any knocking noise the next day.

 

Subfan597, thank you for your kind comments. The oil consumption isn't the most pressing issue, as adding oil is easy. The real issue is the CEL repeatedly comes on with code P0521. I took it to a 2nd dealer. Unfortunately, both dealers agree the CEL reflects marginal oil pressure. The 2nd dealer stated I had a rear main seal leak, which the first dealer made no mention of. The 2nd dealer suggested starting with replacing the oil pump on the basis of an 0-ring at the top of the pump may be leaking after 11 yrs of service, contributing to low oil pressure. I am waiting on a price quote for this service. I will up date the forum if there any breakthroughs on this vehicle. THanks for everyone's suggestions!

 

I might roll the dice and go for a new rear main seal and oil pump, as it seems to have been a pretty good truck for you. That might get you another 50 to 75K miles. I would definitely draw the line on the repairs, as the next thing the dealer would want you to buy a new engine, or worse a new vehicle. Do you have a good independent mechanic in your area?

My 2001 Yukon XL came from the same area as yours, Amelia Island and Waycross GA. I "stole" it, under the cover of darkness and brought it up north. We will be soon heading south for the winter at St Simons.

Good Luck

 

Thanks!

 

there is some TSB that address the issues


on the oil consumption i would switch to 5w30 mobil1 or 0W30 mobil1 there is also an update valve cover that should help with the consumption



the oil pump could be worn out .. i'm seeing 70PSI on a cold start and 60PSI normal driving i.e 1500rpm (on 6.0l) but it does have the corvette oil pump.. variable displacement oil pump..



also your oil sensor could be bad or the oring is bad sucking up air VERY COMMON and the oil sensor screen can be clogged i suggest bringing the oil change interval to 4,000 miles

 

Dealership mechanic suggested replacing oil pump and o-ring at cost of $1,500. He mentioned the "air sucking" tendencies as well. I am contemplating that route. Will update. Thanks!

 

When I bought my Burb it had a "new" junk yard crash engine in it. That was three years ago. I'd do that again in a heart beat. So, all is not lost if you need an engine get one from a wreck. Resale isn't a huge issue because it's as good as it will ever get anyway.

 

I have a fleet of Suburbans, Denalis, Escalades, Running PHL EWR JFK. NYC PHILA
I prefer the 5.3 with sequential firing with regular gas over the 6.0 premium gas.
At about 250k, they start using a little oil. I turn them at 360k.
After 360k they still run and drive good, just don't look as good. My drivers and customers scoop them up before they hit the market.
Oil Changes every 10,000 use synthetic.
Typical wear parts,
Hubs
Control Arm Bushings
Struts Shocks
They run pretty much 24/7 the 5.3's get about 18-19 MPG the 6.0's 16-18MPG And you'll see them 75MPH on the Jersey TPike
The faces of the damned cheap AC and Radio buttons always wear off right away.
The key fob locking systems always have problems. Always use a regular key.
Also have Fords, Lincolns, MB's and BMWs
Personal drivers are Fords and BMWs.



Never had one motor or trans blow.

 

Thanks for sharing this. People talk trash about the 4L60e transmission but.. My Suburban has 247,000 (engine was replaced when I bought it) on the transmission. I changed the fluid and filter when I bought it three years ago. I tow my travel trailer with it and it's still running and shifting perfect. Granted, I drive it like grandpa 90% of the time. I'm going to drive it till I decide to do something else.

The back story on the engine. The lady that owned it let the oil run dry, it seized. It was sent to the junk yard where another, perfectly good, 50,000 mile 5.3 was in a wreck. The engine was switched out, new brakes, new tires, driver's seat reupholstered and it's on like donkey kong. I'm real **** about servicing.

 

Thank you for your kind comments. After considerable deliberation, I opted for a remanufactured engine from the dealership. They offered me a salvage engine as well, but my limited experience with salvage parts was very unfavorable. I still don’t understand why I was not able to replicate others in making this engine last longer. It always had Mobil1 5W30 full synthetic oil and either the Mobil1 or the top of the line Fram filter. The only thing I changed on it was, after the 100,000 mile powertrain warranty expired, I switched over to Mobil1 15,000 mile oil and changed it religiously at 15,000 mile intervals. Maybe that wasn’t a good idea. Never know for sure. Thanks to everyone!