warranty

"Malcolm William Mason" skrev i en meddelelse news: snipped-for-privacy@4ax.com...

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...

"can clog", since you asked.

I'm not sure what year you are talking about, but for newer models, the recommended interval is kind of confusing. The warranty covers scheduled maintenance, which is at 15000, 30000, etc. miles. The SID will even tell you the oil is fine until you hit those intervals. In the manual though, the recommended oil change interval is 5000 miles. It seems to me those oil changes should fall under scheduled maintenance too, but I guess they doesn't. This is confusing and misleading.

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

Yes, I'm not sure I understand how blowby of gasoline would cause sludge, however...

Right.

I think the key, Fred, is in how the oil vapors are recovered by the PCV system. There is a, well, a box at the bottom/back of the engine that condenses the mist back into liquid, to drain back into the sump. There's a small orifice going into this box, I'm guessing to limit airflow. Problem is, that mist then gets "mistier" while hot, in an oxygenated environment. Chemicals oxidise more rapidly when they're in smaller particles, _and_ when they're hot - both conditions which occur in this particular PCV oil reclaimation method.

Google for HSA (Hot side aeration). To get the homebrewing links out of there (it occurs there as well), try this string hot side aeration oil sludge -beer

I'd bet a bottle of nice Scotch that this is the cause of the problem, maybe made worse by combustion byproducts blowby past the piston rings.

Dave Hinz

FWIW the Toyota's Camry & Highlander V6 has a notorious "sludge" problem; there's plenty of info on their respective boards.

"Dan" skrev i en meddelelse news:5aEne.591$ snipped-for-privacy@news.uswest.net...

Are you talking about the current 9-3?

Yes, but not so for the Saab engine. I can post pics of the difference of the pistons, from 9000 to 9-5, if you wish. :o)

Cheers!

"Malt_Hound" skrev i en meddelelse news: snipped-for-privacy@adelphia.com...

The oil getting a bit thinner, but not a problem. The gasoline however, tears the oil apart - destroys it. That's why the oil turns into sludge. It's the same thing if you where to drive 50.000 miles on the same oil. Once the additives and molocular structure of the oil, can't stay together anymore, you'll get sludge. The gasoline does the same, just more rapidly...

Confirms the facts. ;o)

Cheers!

Yes. I have a 2004 9-3 Aero USA.

I'm almost positive that somewhere in either the owner's manual or the service manual for my 2004 9-3 Aero, it actually recommends a 5000 mile oil change inteval. Of course, I can't find anything to back that up now. I'm nearly certain I read 5000 somewhere, but I'll admit that there is a non-zero probability that I made the whole thing up.

"Dan" skrev i en meddelelse news:LbJne.2087$ snipped-for-privacy@news.uswest.net...

There's your reason. The engine in your car, isn't based on the original Saab-design, but is a development from GM - full alu engine. It's completely different, from the engines in question.

Cheers!

If you find it in the manual please point to the page. When I first got my car I asked on saabcentral and the response was to follow the computer directions.

Dan

The SID is definitely not an accurate measure of oil quality. It does not actually monitor oil quality; it only makes estimates based on driving conditions. I change my oil every 3000 miles and the oil quality reading never increases, only steadily decreases.

I'll keep searching for the 5000 mile recommendation, but, like I said, I might have imagined it.

Turns out I didn't imagine it (but it isn't actually in the manual). Are you registered on owners.saabusa.com? Check out the maintenance schedule section:

Engine Oil and Filter Change Service will be determined by the service indicator reminder on your SID display. Interval: Every 5,000 miles.

Well, my 2004 9-3 Aero USA's SID did not remind me until I was approaching 15K miles since my first oil change at 1K miles.

Since this has intruiged me I looked for info on my '93 9000. Couldn't find my owner's manual but did find info on saab9000.com.

Of course they didn't have the sludge problem. Is it *really* fuel getting into the oil. I just heard it was bad crankcase breathing - but I can see some logic in Henrik and Dave's comments.

Graham

I have to confess I'm not aware of the details of the latest 4 cyl engines.

How much similarity is carried over from those we know typically to be found in

Graham

Almost all of the people with sludge problems in the Toyota V6 have no documentation of oil changes. Those that do have documentation have shown an ignorance of driving conditions. They refuse to acknowledge that short trips where the engine never warms up is considered severe driving conditions. They look at the manual and see the oil change interval of 10,000 miles and select that, because it is convient. They ignore the much more frequent oil change interval under severe conditions. We have a Sienna with the V6 - no sludge issues, but then I still drive my 1982 Volvo turbo and 1992 Saab 900. The secret - -

-change the oil every 5,000 miles with synthetic. The Sienna is subject to frequent short trips - severe driving conditions.