Contaminated oil - vs - contaminated sample

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Oct 7, 2002
Southern California
I just posted my results of an interesting and disturbing oil analysis in the Used Oil Analysis Section. My silicon number is quite high yet my wear numbers look really good. I have to consider that either myself or the oil analysis lab may have contaminated the sample. I sample with the Amsoil sampling pump through the dipstick and use new tubing for each sample. So, can you oil analysis pros spot a contaminated sample versus just plain old dirty oil? I will be draining the oil and taking my 10k sample in the next few days. That sample should confirm whether the silicon count is for real or simply an error.
If the silicon comes from RTV and similar sealants made of silicones, a form of silicon, you won't have high wear numbers from the gritty type of silicon called "sand" and dirt.
At 28,000 miles it should be finished breaking in. All the other numbers are very consistent so the high silicon is strange. Personally, I would not worry about this as the wear numbers are great. Could be a bad result, some outside contamination etc but if this high a silicon is dirt you would see considerably higher iron numbers as well as others. You can call the lab and ask to recheck but I would not jump off of a cliff due to this one number. You have great trend analysis here and one strange number does not a problem make.

I also have used the Amsoil tube etc. but unlike you I uese the same one everytime and just blow it out. I don't think that whatever is left in the tube can cause much of a problem, at least it has not for me.
UPDATE: I just posted my 10k mile results in the UOA section. Silicon dropped from 54 to 19 which confims my suspicion that my 7.5k mile sample was contaminated.
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