9-3 9-5 Engine Sludge

The 9-3 models from 2000 until 2002 ( also 2003 convertibles) and the 9-5 models from 1998 until 2003 (4 cylinder engines only) are prone to have engine sludging issues. The reasons are varied, including a defective crankcase ventilation system, poor maintenance, incorrect oil, and unrealistic oil change intervals To meet more stringent EPA emissions standards, most manufacturers located the catalytic converter directly below the engine sump (oil pan) to help bring the engine to normal operating temperature more quickly and also increased the normal operating temperature. A cold engine uses more fuel and produces more emissions. In our examining many engines it appears that the oil in the shallow part of the oil pan actually cooks which results in a substance with the texture of coffee grounds. This material is washed into the lower area of the pan, and directly into the oil pickup screen. This process gets worse over time as the screen gets more and more restricted, finally resulting in the oil pressure light flickering occasionally while the engine is running. These are called idiot lights because they are triggered at approximately 5 pounds of pressure, substantially less than normal oil pressure.

Crankcase Ventilation System

In 2006, Saab released PCV update #6 and strongly recommended that all affected cars have the update installed. We still see cars regularly with the original crankcase ventilation system. The crankcase ventilation system is supposed to remain under a vacuum to draw fumes from the crankcase to be reintroduced into the intake to be burned. The original PCV system and subsequent attempts to correct were inadequate at best. Vacuum is marginal at idle and non-existent with foot on the brake.

Another frequent problem is a bad or incorrectly installed pcv check-valve. The check-valve is intended to prevent the crankcase from being pressurized when the turbo is producing boost.

Symptoms are oil leaks and sludge build-up leading to failed turbocharger and complete engine failure..

We constructed a simple tool to verify the proper operation of the pcv system (thanks to Chuck Andrews.)

Proper Oil and Oil change Intervals

The owner’s manual had oil changes required every 10,000 miles for some years. SaabUSA now recommends changing oil every 5,000 miles and only Mobil1 0w40 full synthetic oil.


We have seen sludge problems on cars with no maintenance history as well as cars with complete history and all scheduled maintenance. Because the pcv update came out so recently, just because a car has the pcv update, that doesn’t mean it won’t have a sludging issue. Caught early the problem is usually reversible. To check for sludge deposits, the oil-pan needs to be removed from the car. Then the baffle plate is removed, then the oil pickup tube. We recommend the ABC Sales sludge/Debris accumulator oil pan. This pan is a direct replacement for the original but has a clean-out immediately below the oil pickup screen. This allows inspecting and cleaning the screen to be carried out without removing the pan again. Cars found to have a sludge problem are fitted with the ABC pan and a new pickup tube. Then we use B&G Engine purge to flush the engine. Without the ABC pan, this would likely result in clogging the new oil pickup screen.

A mostly blocked oil pick-up screen.

Sludge deposits in the bottom of an oil-pan.

Inspection plate from ABC oil pan showing residue after performing engine flush with B&G engine purge.

Oil pick-up screen, viewed through inspection port on ABC oil pan showing residue after performing engine flush with B&G engine purge. The screen is easily cleaned.

The inspection can be easily performed at each oil change.