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Discussion Starter · #22 ·
Update: I ran BG Dynamic Engine flush through the car yesterday. It ended up being a 6 liter container that I got from a local dealership's parts guy.

So I ran the first flush with straight BG Dynamic Engine flush, following this protocol, and the second with 50% BG product / 50% motor oil. Then I did a third rinse with standard motor oil.

During the procedure I used an oil pressure testing kit to monitor the oil pressure. I noticed something funny during each cycle. The oil pressure would run at about 38-39 psi during the first minute of running the engine at 3,000 rpms. Gradually over the course of a 20-minute interval of holding a constant 3,000 rpms, the oil pressure would drop off to about 28 psi and hold steady at that lower psi. It did the same thing with both the initial BG product and the final rinse with 0-40 full synthetic oil.

Any idea why it would do that? Is that a normal thing? I don't know enough about how oil pressure works to know if that's a problem or normal behavior.

BTW, I haven't had time to pull the valve cover yet and see how it did with the de-coking. I'll do that soon and get some results photos on the forum.
 

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Update: I ran BG Dynamic Engine flush through the car yesterday. It ended up being a 6 liter container that I got from a local dealership's parts guy.

So I ran the first flush with straight BG Dynamic Engine flush, following this protocol, and the second with 50% BG product / 50% motor oil. Then I did a third rinse with standard motor oil.

During the procedure I used an oil pressure testing kit to monitor the oil pressure. I noticed something funny during each cycle. The oil pressure would run at about 38-39 psi during the first minute of running the engine at 3,000 rpms. Gradually over the course of a 20-minute interval of holding a constant 3,000 rpms, the oil pressure would drop off to about 28 psi and hold steady at that lower psi. It did the same thing with both the initial BG product and the final rinse with 0-40 full synthetic oil.

Any idea why it would do that? Is that a normal thing? I don't know enough about how oil pressure works to know if that's a problem or normal behavior.

BTW, I haven't had time to pull the valve cover yet and see how it did with the de-coking. I'll do that soon and get some results photos on the forum.
So you just bought the flush, not the whole kit?
How much did it cost?
Run it for 40 minutes each time? How much gas did you use? lol
Maybe some of that carbon broke off and is obstructing the pickup?
Did any chunks come out when you drained the oil?

I'd recommend dropping the sump when you pull the valve cover.

Edit:
If you started the test with a cold engine, that could explain the higher initial PSI reading. Then as the oil heats up it thins out and the PSI drops.
Looking through the WIS it says the minimum oil pressure at 2000 RPM with a warm engine (and 10w30 oil) is 2.5 bar or 36PSI. At 3000 rpm and a thicker oil I'd expect this to be higher.
28PSI seems to be on the low side
 

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Discussion Starter · #25 ·
So you just bought the flush, not the whole kit?
How much did it cost?
Run it for 40 minutes each time? How much gas did you use? lol
Maybe some of that carbon broke off and is obstructing the pickup?
Did any chunks come out when you drained the oil?

I'd recommend dropping the sump when you pull the valve cover.

Edit:
If you started the test with a cold engine, that could explain the higher initial PSI reading. Then as the oil heats up it thins out and the PSI drops.
Looking through the WIS it says the minimum oil pressure at 2000 RPM with a warm engine (and 10w30 oil) is 2.5 bar or 36PSI. At 3000 rpm and a thicker oil I'd expect this to be higher.
28PSI seems to be on the low side
Good questions:
1) I couldn't get the whole kit locally. The local distributor for BG doesn't stock anything except the Dynamic Engine Flush itself. The parts guy at the dealership said he thought the rinse product was unnecessary and that normal oil would do the same thing.
2) $180 for the Dynamic Engine Cleaner by itself.
3) 40 minutes for the Dynamic Engine Cleaner per the spec. 20 minutes for each rinse after. (Don't know on how much gas, not that much.)
4) It's possible. I had the same thought when I was watching the gauge during the first application. Then when it repeated the same exact pattern three times, I was a little confused. No carbon chunks came out with the draining from the pan. It was all liquid and very black for the first two rounds. Third round came out fairly clear.

Lastly, thanks for looking that up on the WIS. That's great info on the oil pressure spec. I'm going to pull the valve cover first (because that's really easy). Then I'll see about dropping the pan.

The engine warming up theory is interesting, but I did the swaps pretty quickly, so the engine itself didn't have a chance to cool down that much in between. And the coolant temperature stayed right in the mid zone throughout.
 

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Whoa, 180 bucks. Seems pretty steep considering you didnt get the rinse, fuel treatment or oil additive that the kit comes with. Hopefully it was money well spent. I cant wait to see what's under that valve cover!


The engine warming up theory is interesting, but I did the swaps pretty quickly, so the engine itself didn't have a chance to cool down that much in between. And the coolant temperature stayed right in the mid zone throughout.
The engine may have been warm, but the oil you poured in was room temperature and not the 100c you'd expect from hot oil.

As viscosity decreases, naturally you will start losing oil pressure.
 

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Discussion Starter · #27 ·
Whoa, 180 bucks. Seems pretty steep considering you didnt get the rinse, fuel treatment or oil additive that the kit comes with. Hopefully it was money well spent. I cant wait to see what's under that valve cover!




The engine may have been warm, but the oil you poured in was room temperature and not the 100c you'd expect from hot oil.

As viscosity decreases, naturally you will start losing oil pressure.
Thanks! That's really helpful to see that chart. And that makes sense.
 

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One contributing factor to sludge is premature engine shutdown. Now while our beloved Saabs are "genetically" prone to it, it is also true of any turbo engine from any maker that shutting down a hot engine causes problems with both the turbo and the oil.

Basically sludge is cooked oil. The oil lines to and from and (particularly) the capillaries around the turbo are very hot when the turbo is spinning. So when the oil stops pumping at shutdown, the oil around the turbo can cook. The when the engine is turned on again, fresh oil pushes the carbonised sludge back to the sump.

Now it usually leaves the lines lined with hard carbon thereby reducing the oil cooling of the turbo in future. If hot shutdowns are repeated, this in turn eventually leads to an expensive turbo explosion... or heart attack if you will. This is the reason turbo timers were invented.

A good (scratch that)... essential habit to have with any turbo engine is to let it tick over for a minute or two before turning it off. This keeps the oil pumping around the turbo while the turbo temperature cools down. The bigger the turbo, the longer it takes. In 16 litre trucks engines it can take 3 to 5 minutes. But in cars it literally only takes a minute with a healthy turbo. A Pyrometer is a great tool for watching the magic as it happens. A turbo timer is even better to stop the issue in the first place.

Once again, this is not the single cause of Saab sludge... but it is the same basic principle. So just imagine that the whole engine is (unfortunately) designed with several hot spots throughout the engine and you'll understand what an issue it is.
Thats true only when after driving on highway, 1-2 min cool down is good but what really contributes to oil sludge is long oil changes, many people get misled by automakers which instruct them to 20-30K km oil changes that is ridiculously stupid, NO OIL last that long regardless of what they say.
Do frecuent oil changes 7.5 to 10K km and you will not need to worry for sludge.
 

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Thats true only when after driving on highway, 1-2 min cool down is good but what really contributes to oil sludge is long oil changes, many people get misled by automakers which instruct them to 20-30K km oil changes that is ridiculously stupid, NO OIL last that long regardless of what they say.
Do frecuent oil changes 7.5 to 10K km and you will not need to worry for sludge.
In Europe, 20-30k is pretty much the standard now. However, on average the synthetic oils in Europe are better than the synthetic oils in North America. Europeans have a stricter definition of synthetic oil, by law a synthetic oil in most European countries means it must have Group IV base stocks. What this means is that the base stocks consist of actual synthetic oils, called PAO's. This used to be the case in the United states as well until about the 2000's, when Mobil1 tried suing Castrol over claiming their non-PAO oils as synthetic. They lost, and as a result most of the synthetics we see here in America are made up of group III base stocks. Group III are basically highly refined mineral oils, and not true synthetic oils. As such, do not have the longevity of a PAO motor oil.

Granted there are benefits to using Group III based motor oils.
  • significantly cheaper
  • I change my oil at around 6-7k, at this type of interval I don't have to top up my oil between changes. If I went 30k I'm sure i'd have to top up.
  • don't need to use more expensive oil filters
 

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In Europe, 20-30k is pretty much the standard now. However, on average the synthetic oils in Europe are better than the synthetic oils in North America. Europeans have a stricter definition of synthetic oil, by law a synthetic oil in most European countries means it must have Group IV base stocks. What this means is that the base stocks consist of actual synthetic oils, called PAO's. This used to be the case in the United states as well until about the 2000's, when Mobil1 tried suing Castrol over claiming their non-PAO oils as synthetic. They lost, and as a result most of the synthetics we see here in America are made up of group III base stocks. Group III are basically highly refined mineral oils, and not true synthetic oils. As such, do not have the longevity of a PAO motor oil.

Granted there are benefits to using Group III based motor oils.
  • significantly cheaper
  • I change my oil at around 6-7k, at this type of interval I don't have to top up my oil between changes. If I went 30k I'm sure i'd have to top up.
  • don't need to use more expensive oil filters
Thanks, this information is good.
 

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In Europe, 20-30k is pretty much the standard now. However, on average the synthetic oils in Europe are better than the synthetic oils in North America. Europeans have a stricter definition of synthetic oil, by law a synthetic oil in most European countries means it must have Group IV base stocks. What this means is that the base stocks consist of actual synthetic oils, called PAO's. This used to be the case in the United states as well until about the 2000's, when Mobil1 tried suing Castrol over claiming their non-PAO oils as synthetic. They lost, and as a result most of the synthetics we see here in America are made up of group III base stocks. Group III are basically highly refined mineral oils, and not true synthetic oils. As such, do not have the longevity of a PAO motor oil.

Granted there are benefits to using Group III based motor oils.
  • significantly cheaper
  • I change my oil at around 6-7k, at this type of interval I don't have to top up my oil between changes. If I went 30k I'm sure i'd have to top up.
  • don't need to use more expensive oil filters
This is why I prefer running "German Castrol". Unfortunately they don't have the weight for the Saab so I use Mobil 1. Many years ago, on another forum someone sent samples to Blackstone to verify the differences which I thought was pretty interesting.
 

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Here in Finland we have SAAB/GM Dexos2 super synthetic oil (5W-30) which is priced economically. Price is just around 20-25 EUR/ 5 litres
Oil meets following: .ACEA C3 (former A3/B4), API SN/CF, GM-LL-A-025, GM-LL-B-025, MB 229.51, VW 502.00, 505.00, 505.01
 

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Discussion Starter · #33 ·
Update: Finally pulled the valve cover off after having run the BG protocol with Dynamic Engine Cleaner. The upshot is the flush did something, but nowhere near tackling a problem of this size.

I think I’m in the camp of just driving it and doing oil changes at a more frequent interval, say every 1,500-2,000 miles.

I’m pretty sure that to actually clean it out I would need to pull the engine and do a rebuild. I’m probably not going to get to that this year.

280665
280666
280667
 

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Put some diesel in a spray bottle, and spray it all over, and let it sit over night. Repeat the following day. It will soften up so as to remove pieces. Shove a rag down there that you can pull up without it unfolding and dropping all the sludge.
 

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Discussion Starter · #37 ·
Put some diesel in a spray bottle, and spray it all over, and let it sit over night. Repeat the following day. It will soften up so as to remove pieces. Shove a rag down there that you can pull up without it unfolding and dropping all the sludge.
I hear what you’re saying. The consistency is such that it’s easy to flake off. It’s like burnt marshmallow. It crumbles away without difficulty. But it’s a double-edged sword: There is no way that I could shove a rag down there without knocking loose loads of coke. I’m afraid most of it would end up in the sump/throughout the engine while trying to clean it that way.
 

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I hear what you’re saying. The consistency is such that it’s easy to flake off. It’s like burnt marshmallow. It crumbles away without difficulty. But it’s a double-edged sword: There is no way that I could shove a rag down there without knocking loose loads of coke. I’m afraid most of it would end up in the sump/throughout the engine while trying to clean it that way.
The diesel will soften and bind it together. I've had the same situation a BMW engine. Took the valve cover off and .......dear God!!!

Forgot to add. Spray first before trying to a rag in there.
 
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