RTV, etc. Si effects on oil

[JHZR2]

Hi,

I posted a question like this but i think when those worms went through the board some time back, it made it get lost. The title exists, but there is no thread.

I am curious about Si and its effect on used oil analysis. I c an understand that if you have silica sand getting into your engine, some of the extremely fine particles may stay in the oil, may dissolve, etc., showing up in a used oil analysis.

But is it the Si itself that alters the oil chemistry, causing it to not work as well and screw up the wear numbers? Or is it the possibly abrasive nature of the suspended fines?

If one uses RTV sealant when setting a gasket, chances are despite any sure time, it will show elevated Si in the oil. This happened in my mother's car, which has severe service, 5 block commutes, all cold driving, etc., and her m1 filled engine didnt show anything odd at all.

But was that abnormal? Would typically the presence of Si (not in an anti-foamant application) in oil cause increased wear, or is it really the influx of silica sand/dirt that is the culprit? If I use RTV on my GF's valve cover gasket, and it puts Si into the oil, should I be concerned?

Thanks,

JMH

 

[Quest]

Thought Silica is about solid particulates, how can that correlates to RTV silicone may I ask?

 

[JHZR2]

well the fact is that a used oil analysis shows 'Si' concentrations. When people see elevated Si in their oil analysis, the usual suspect is an intake that isnt sealing. An intake isnt taking in RTV, but it may be taking in silica sand (SiO2). Under temperature, pressure in an engine, it may break down or something, or the crystals may just break apart into VERY tiny bits that dont get filtered, and show up in an analysis.

I dont see how Si from RTV sealant could cause excessive wear, and most talk about leaky intakes tells me that it is Si from the environment. So I am curious about the mechanism that takes elevated Si to elevated engine wear metals. Is it the particle breakdown in an engine that causes wear, or is it Si itself, effecting oil chemistry that screws up the oil, causing higher wear?

JMH

 

[Quest]

I must admit that other than some acidic fumes that used in RTV silicone sealant that may affect/damage emission components (CATs, O2 sensors), I'm not familiar with Si other than air-filter sealing/filtering problems or air leakage problems.

I too, would like someone to pitch-in with their interpretations to your questions.

 

[Jay]

Simple FTIR analysis can't distinguish between silicon and silicone. The former is harder than steel, and is extremely abrasive--even in small amounts. The latter is non-abrasive; in fact, silicone can even be a lubricant.