oil buildup in ls head intake passages

[sgian]

I hope I'm posting in the right place for troubleshooting. The vehicle is a 2005 Chevy 4WD with a 5.3 ls engine with about 175,000 miles. I took the intake off to replace the gasket, and saw this...

I'm thinking that might be too much oil buildup in the intake passages in the heads. Is it? Also, if I don't fix the oil buildup, will it cause the new intake manifold gasket to go bad?

I was hoping this would be the last 6+ seater I would have since my kids are getting older and might start moving out in a couple years. So I need this repair to last at least several years. Oil consumption is less than a quart between 3,000 mile oil changes. Under the lifter valley and valve covers, it is clean. Some time ago, maybe a year, I did a compression test and all cylinders were between 190 and 195 psi, which I thought was high but seems to me to indicate that the piston rings are ok. I don't believe the PCV is serviceable on this vehicle, so it isn't a matter of replacing a valve. So does that leave the valve stem seals as the most likely culprit if this buildup is excessive? I don't have access to a leak down tester.

 

[87vette81big]

That is typical Gunk buildup using Todays Pump Gas.
So much for EFI Keeping intake valves clean.

In the Past GM TOP ENGINE CLEANER WORKED GREAT.
ITS BEEN DISCONTINUED.

GO OUT AND BUY A 1 QUART BOTTLE OF MARVEL MYSTERY OIL.
WE CALL IT MMO.
POUR 6-8 OUNCES IN THE GAS TANK WITH 10 GALLONS OF GAS.
DRIVE NORMAL.
1 DAY LATER ROMP ON THE ENGINE HARD TO 80-90 MPH ON AN OPEN ROAD.
ALL THAT GUNK WILL BE GONE IN THE INTAKE PORTS AND FROM THE BACKSIDE OF THE INTAKE VALVES.