Can anyone explain how silicon gets into the crankcase? (and other oil analysis q's)

[RobZ71LM7]

How does it get from the air filter to the crankcase? I've got a bunch of people arguing with me over my oil analysis. It showed 15ppm of silicon and I said it was due to the K&N air filter and I'm switching-and they say that's b.s. Some people will not believe hard evidence no matter what you do.

 

[Pablo]

Is 15 PPM high? can't really say, just reading your post.

Air carrying dirt (measured as Si) can pass thorough or around an air filter.

But - How many miles on the oil, do you live a dusty area, does your car have silicon in the gaskets, high Si Al alloy part(s), Silicone rubber intake hoses, silicon sealant used, etc?

I would not immediately condemn one brand of filter - for one analysis that show 15 PPM - insufficient information....

[ November 25, 2002, 11:11 AM: Message edited by: Pablo ]

 

[dragboat]

True,,some oils contain up to 10ppm as a antifoam and some call anything more than 20ppm dirt,,depends who you talk to.

 

[dickwells]

To address the original question: I have a feeling that the filter for the PCV system is pretty crude but it usually draws from filtered air in the intake system. Voila! Dirty air gets sucked into the crank case. RW

 

[RobZ71LM7]

I've had three analysis with K&N's come out 15-20ppm. I'm going to try swithcing one of the cars to paper and see what it reads.

 

[RobZ71LM7]

quote:

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Originally posted by dickwells:
To address the original question: I have a feeling that the filter for the PCV system is pretty crude but it usually draws from filtered air in the intake system. Voila! Dirty air gets sucked into the crank case. RW

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Other way around-the engine's vacuum draws air from the crankcase.

 

[Bio-T]

On my last oil analysis I had 23ppm silicone. But the wear metal were very low so it wasn't from dirt. But as Dragboat stated, the virgin analysis showed silicone at 10ppm, and the engine only had 2K on it when I did this oil change and ran the oil for 3K miles and then had it analyzed.

Not being an oil analyst, I would say that if the wear numbers are low, don't worry. If the wear numbers are high along with the silicone readings, look for air intake/filter problems.

[ November 25, 2002, 12:33 PM: Message edited by: 59 Vetteman ]

 

[dickwells]

Actually the engine vacuum draws air THROUGH the crank case and it comes from the "clean" side of the air filter system. All this talk of silicon levels does not mean much without knowing the miles on each sample of oil. Realistic talk of silicon should be based on PPM/mile or PPM/hr or some stable base. I just posted an analysis which shows 28PPM iron but that was 3.65ppm/Kmile which is not too bad. I expect it to go down on the next sample. The same sample showed nearly a hundred parts silicon but with the low wear it is apparently from the seals.

 

[metroplex]

Keep in mind that the seals for the PCV valve and crankcase breather tube are generally not 100% leakproof.

My PCV grommet isn't super super tight - there's a chance some dirt can get in there.

AND as someone stated before - Silicone can come from:

RTV (uses Dow Corning 500 silicone oil)
Silicon-Alloy pistons/rotating parts (anti-wear)
engine oil component
some materials from air hoses vacuum tubes, etc...

I think you need to do an analysis of dirty air to really see how much Silicone there is (from dirt, etc).

 

[RobZ71LM7]

Thanks for the correction ****. I had 15ppm on my oil after 2200 miles which I think is excessive. Other people with the same oil in similar cars have had significantly less. All of my hoses have great seals.

 

[Pablo]

I love it!! REAL Metrics....

I can now also agree,sadly

that the level of Si seems high for the mileage. I had less Si in my turbo in 10,000 + miles...and that car gulps prodigous quantities of air....(can't remember - it was 12ppm or something, too lazy and burnt to look)

 

[Bror Jace]

Red Line uses something like 10-15ppms of a silicon-based anti-foaming additive. I use a K&N cone shaped open air filter ... but only service it every 30,000 miles or so.

After 7,232 miles, my silicon PPM level was 14.

--- Bror Jace

 

[Mike_dup1]

What is the topic? Silicon or Silicone

Silcon - Chemical element forming Silica

Silica - Glassy mineral found in the form of quartz

Silicone -Silicon compond resistance to heat, water, etc.

Silicon in the oil most likely comes from dirt entering the air intake system.

Silicone in the oil may come from gasket materials used in engine assembly.

So, it would seem to me that any amount of Silcon in the oil is to much, the lower the better. Its grit and will evently cause wear.
Agree ?
Disagree?

[ November 29, 2002, 12:42 PM: Message edited by: Mike ]

 

[widman]

Unless the oil uses a lot of silicon for anti-foam, or the engine is new, 15ppm is reasonable but I feel on the high side on 3000 to 4000 miles. Wear metals tell the story. I try to keep silicon under 15ppm, but as you can see from this analysis
http://american.netfirms.com/analisis/tierra/tierra.html
there are people who will do anything they can to screw up an engine.

 

[SteveD2]

quote:

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Originally posted by Mike:
What is the topic? Silicon or Silicone
....

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The oil analysis cannot tell silicone from silicon--it all reads as ppm of Si.

As said, Si can come from seals and gaskets leaching, from anti-foam additive in the oil, and from dirt.

Ken

 

[metroplex]

If you look at your PCV grommets and crankcase breather grommets you will usually see a lot of dirt stuck next to it.

Chances are, a few specks of these might fall in from time to time causing a higher Si reading.

Remember ppm is very small, so a few grains of dirt or sand would probably throw it off.