QUOTE(Dezs @ Sep 10 2022, 01:12 AM)
Hey TS, wanted to check in with your opinion on my engine oil test. Car is milotin 1.5L Maibi manual.
P2 Myvi 1.5 2012
Odo : 165150 km
Date: 6-7/9/2022 on cheapass recycled A4 paper)
Oil Age : +- 4500km/10000km, 3/6m interval
........
There are 2 sets of samples here, 2 drops each time for consistency, left was first and right was a day later w time since the sample was taken. I got a bit concerned over the oil still being clear, but forming rings indicating soot/contamination? I used a 2nd piece of paper to get the next set on the right to validate, but the rings did not seem to form as clearly even though taken cold as well. Hot sample was taken for reference.
The dark paper marks appeared after the oil was left overnight. Initially the moire patterns were not really there. Drive wise the engine feels perfectly fine and no noticeable loss of power/smoothness/etc throughout its life. The carbon cleaning did noticeably reduce low rpm vibrations after, so its really hard for me to tell by feel if the engine is different than the years before.
Note 1st and 2nd test were on different A4's. 2nd one all on the same piece.
Thank you for the quite a detailed elaboration of sample taking.
For consistent comparison, I'm looking at the LHS 24 hr hot sample among the six and assume it as 10,000 km sample, CMIIMW.
There is absence of a darkened/blackish Centre Zone (of about 8 mm in physical sample on hand), transparent and not opaque but it is slightly or mildly grayish indicating a very small amount/level of large size/heavy density metallic wear particles.
A darkened aureole zone or perimeter ring encircling the Centre Zone is absent indicating absence of agglomeration phenomenon of combustion by-product particles within the used oil sample.
The Diffusion Zone is generally transparent and not opaque (in particular the outer half of Diffusion Zone) and the inner half is very mildly grayed indicating a very low level of light weight and low density combustion contaminants being spread out within the sample.
There is total absence of darkened or brownish zig-zag edges surrounding the Diffusion Zone indicating there is no signs of cautionary oil oxidation (not saying there is NO oil oxidation phenomenon in this 10k km used oil sample) and water moisture content in this 10k km used oil sample.
Translucent halo surrounding the zigzag edge (absent, for now) and Diffusion Zone points to the absence of fuel dilution phenomenon, as is normally the case with Maibi engines.
Overall, this rojak mixed oil at 10k km is holding up very well and is still in continuing serviceable condition if one so desires.
QUOTE
Current engine oil mix is a bit zhapalang of 5w30 leftovers though (oldest shelf life about 3yrs):
- About 60% Castrol Magnatec Start Stop Fully Syn 5w30
- About 40% of Motul 5w30 + Shell Ultra 5w30 Fully Syn
This rojak or mixed engine oil seems to me to hold up well at 10k km usage, at typical oil change interval by our local OEMs.
So much for engine oil cannot be mixed, in real life at reasonabe oci imo.
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Car history is fully syn mostly with on time servicing. Engine has recently run through a carbon cleaning via throttle body injection about 2 weeks before taking the sample. Fuel also 2 got tanks with injector cleaner about the same time.
This flushing out of stucked contaminants seems to be reflected in the 36 hr cold sample where a darkened (though slight) aureole zone/ perimeter ring can be observed, if one of two samples is at a lowly 4500 km.
QUOTE
Reason of concern: I am using an oil air filter that probably is not quite as great at filtration over the past 1.5yrs in the name of airflow and efficiency. Am worried if its causing severe wear, or maybe if it might be remnants of the carbon cleaning?
Your after market air filter is working normally. From the blotter spot sample here, I don't think there is any abnormal, let alone severe metallic wear and your worry is unfounded imho.
Yes, the 'dark paper marks' are indications of light weight and low density carbon contaminants as a combustion by-products. I believe these contaminants are
NOT metallic wear parts, which are supposedly of heavier weight and high density.