how dirt is si on uoa's

[sxg6]

first off, i apologize in advance if this is in the wrong forum, i dont know where to post it.

anyways, from what i understand elevated silicon levels in used oil analysis can indicate poor air filtration, or even an airbox leak. i was wondering how dirt or contaminates which come in thru the intake system translate to high si #'s on used oil analysis?

 

[Spector]

Usually seen very quickly in the iron PPM. However, like all things high Si is not always dirt. I got back an analysis this week that showed 110 ppm of SI when al previous samples were in the low teens. All wear metals were normal, especially iron. Conclusion, the new valve cover gasket replaced at the previous oil change was the culprit, no action needed. In order to know if the Si is causing problems though some trend in oil samples is needed to determine what the norm really is for your engine.

 

[haley10]

What Spector said. Also Si can show from anti-foam additive. That's why it's important to use a good analyst to evaluate the overall total picture. Also, it is possible to ingest dirt and not see an alarming Si level if it's going out the exhaust, but other wear metals will be an indication.

 

[Mike242GT]

All igneous and clastic sedimentary rocks are comprised of silicate minerals; compounds containing K, Na, Fe, Mg and Ca with Si and O. These rocks erode to form soil, which translates to dirt. Just about any sand, silt, dust or clay particles derived from rocks that get sucked into your intake contain silicon. The exception would be limestone or cement dust, which would contain high levels of Calcium. Ca is usually thought to be a good thing in motor oil, but not in this case!

 

[sxg6]

good information, thank you

 

[TooSlick]

I look for elevated levels of Chrome and Nickel, which indicates abrasive wear of stainless steel from the intake and exhaust valves....

TS