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... noise from valve train (lifters) and timing cover (timing chain), oil deposits under valve cover, worn timing chain, etc.
As for why, I will probably get some "dissenting" opinions but here goes:
It is not really the fault of the oil, so the type you use will not make as much difference as how often you change it. Synthetic oil may be better for your car, but switching to synthetic may not help much with this.
Sludge (like jelly) and other deposits ("coke" - bits of carbon mixed with oil that look like tiny oat flakes) form for various reasons. They don't all come out with an oil change or an engine flush. This removes them from the parts that get the most oil flow when the engine runs, but not from under the valve cover, the crank case, the timing cover, or the oil pickup screen.
A few weeks after an oil change, or flush, or valve cleaner (I have tried both), the noise will come back because the same crud you just washed off has landed in the same places.
Driving short distances with multiple cold starts per day (not garaged) in sub-freezing winter weather makes the problem much worse, in combination with poor crank case ventilation (that tiny plastic check valve is a poor excuse for a PCV valve).
If you live in a warm climate, keep your car in a heated garage, drive longer distances at hwy speeds, you are less likely to have the problem.
On some cars the oil pickup screens clog up completely and engines fail. On others like mine (I change oil pretty frequently), the result is engine wear, turbo failure, valve cover leaks and a worn timing chains.
Anders has posted on timing chains, pics of sludged engines, oil pickup screens, etc. and answered a couple posts I made about chain tensioners recently.
It is nothing new, and Saab is NOT the only make that has the problem. I talked to a couple independent mechanics who work on import cars all day, neither one said Saabs are any worse than other cars they worked on.
You can read about similar issues with Audis, Toyotas, a whole generation of cars that came out with what turned out to be poor crank case ventilation systems for reasons of emission control. A shop that did an oil pressure test for me recently told me they cleaned an Audi engine with 27,000 miles where the oil would hardly come out of the drain. (Naturally, the Audi dealer blamed the owner and refused warranty service on the car.)
posted by 68.249.6...
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