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Date: Thu, 02 Jun 2005 11:08:00 -0400
From: Malt_Hound <Malt_Houndnospamm*yahoo.com>
Subject: Re: warranty


Dan wrote: > On 6/2/2005 3:50 AM, Henrik B. wrote: > >> "Malcolm William Mason" <mwm1(spam)nospamedu> skrev i en meddelelse >> news:ehet9190a0m0hjpl4tntkn2mmnong0pm7inospamcom... >> >>> This week I receive a letter from Saab USA stating that a small >>> percentage of certain Saab engines could fail due to oil"sludge" >>> accumulation. >> >> >> >>> Does anyone have any insight to offer? >> >> >> >> Hi Malcolm. >> >> The problem is, that on the newer Saab-engine (I4 with Trionic 7), the >> pistons are smaller (and lighter). The piston rings are also smaller. >> This all to reduce internal weight and resistance, to reduce >> fuelconsumption. This means that during (cold)start, there's more >> gasoline running by the pistons, down into the oil. This wears the oil >> a great deal, so that the oil begins to build sludge. This sludge >> doesn't lubricate very well, and kan cloack (spelling?) the oilfilter, >> oilpump and so on. >> >> Saab has tried for the last 5 years to solve this problem, by >> introducing different types of oil-filtering-systems on the >> inlet-side, which obviously isn't the right way to go. >> >> As the problem occurs due to the coldstart issue, the problem mainly >> effects cars with at lot of coldstarts - short trips. On a longer >> drive, the gasoline in the oil will have time evaporate. >> >> What you need to do, is change the oil (and filter) every 5.000 miles. >> And keep and eye on the oilstick - to check for sludge. Use a good >> fully-synthetic oil - 0W-30 or 0W-40. This will keep you a happy >> Saab-driver for a long time. :o) >> >> Cheers! >> > > If SAAB has a confirmed problem, then why do they recommend a first oil > change at 15K miles for 9-3? > > Also, what you describe being the problem I don't get. With modern > machining tolerances should be tighter and less of a chance for gas to > seep down the cylinder wall... I agree, this explanation of the sludging problem is somewhat lacking. Regardless of the design of the pistons and rings, there is no raw fuel in the combustion chamber to seep down into the crankcase, *unless* you also have a fuel injector leakage problem. Even with that, I would expect thinning of the oil and excessive engine wear, not sludge buildup. If anything, flushing the crankcase with a bunch o fuel thinned oil would *reduce* the sludge buildup not increase it. I have heard of sludge problems on the 4 cylinder engines ever since the recommended oil change interval was increased. I first heard about this when I had a 2000 9-3 2.0l. OTOH, I've never heard of it occurring on engines where the oil was changed at 5k miles religiously. -Fred W

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