N43794 - Blackstone Oil Analysis: Wear Metal Trends

Continental TSIO-360-FB1  |  7 samples: Jun 2021 - Dec 2025  |  Phillips XC 20W50  |  Last updated: Jan 7, 2026

Iron (Fe) steel wear - univ. avg ~85 ppm

Nickel (Ni) exhaust valve guides - univ. avg ~17 ppm

Chromium (Cr) rings / cylinder walls - univ. avg ~16 ppm

Aluminum (Al) pistons - univ. avg ~10 ppm

Silicon (Si) dirt / air filtration - univ. avg ~11 ppm

Fe + Ni + Cr combined valve/guide issue signature

Complete Historical Data Table

SampleTachOil Hrs *FeNiCrAlSiCuPbMoPZn
Universal Avg-~30 hrs85171610118410055809
* Oil Hrs = logbook-confirmed: prior oil change tach to sample tach. All cross-referenced from engine logbook lb400/lb401.
Blackstone-reported MI/HR on Oil was inaccurate for all 7 samples. Do not rely on it.

Confirmed oil change dates from logbook:
2/17/21 T=2855.9 (p.36) | 8/5/21 T=2897.8 (p.37) | 4/4/22 T=2987.1 (p.38) | 3/9/23 T=3089.7 (p.39)
6/21/23 T=3104.7 (p.40) | 12/3/24 T=3252.1 (p.48) | 5/20/25 T=3293.3 (p.50)
Note: 9/3/2025 annual (p.51) did NOT include an oil change.

Tach source (* = derived from logbook, shown in blue on charts):
Oct 2023: tach 3177.8 from Advanced Leesburg WO#3050, exact date match (lb400 p.44).
Apr 2025: tach ~3281 interpolated between 3255.4 (1/16/25) and 3293.3 (5/20/25); Blackstone "1405" was Hobbs.
Dec 2025: tach 3333.3 from Kuhn WO#2025643 dated 12/18/25 (lb401 p.3); sample taken 2 days prior.
Note: Hobbs and Tach track at different rates and one cannot be derived from the other.

Trend Analysis Summary

WATCH Iron chronically 2-3x above universal average. Improved 286 to 136 ppm (Dec 2021 to Jun 2023), spiked to 220 at tach ~3281, eased to 180 at tach 3333. Still elevated but trending right.
WATCH Nickel persistently elevated (2-3x avg ~17 ppm) - Blackstone flagged exhaust valve guide wear in multiple reports. Improved 42 to 22 ppm in 2022-2023, jumped back to 44 at tach ~3281. Dec 2025 drop to 25 encouraging.
FLAG Apr 2025 (tach ~3281, 28.9 oil hrs): Fe + Ni + Cr all rose simultaneously - Blackstone classic triple-metal valve/guide signature. Borescope strongly recommended. Dec 2025 follow-up showed improvement across all three.
GOOD Aluminum dramatically improved from 82 ppm (2019 era) to 6 ppm (Dec 2025). Near-normal and stable.
VARIABLE Silicon spiked May 2022 (tach 3013, 21 ppm) and Oct 2023 (tach 3178, 23 ppm). Currently 7 ppm - clean.
NOTE Phosphorus and Zinc (anti-wear additives) dropped sharply post-2022. Worth flagging with shop on next service.