Ticking sound from front driver side

[9900Eagle]

Hi all…. So I got this ticking sound coming from the front driver side of the motor ISX15 CM2350 with 590000miles. Took it to the shop in Dallas. They checked the cam and rockers (all good/ not damaged at all), did a valve adjustment, clutch adjustment, PM and still ticking.

-no coolant loss
-no oil useage
-PM every 10-12K with T4& Fleetguard filters
- no extra blow by or smoke puffing
- oil pressure is 38-40 when rolling and 19-21 at idle
- no codes, no check engine light

…. I will say it never did or make this sound but did start after using 3/4gal of Lucas when doing a PM. Not sure if it’s a coincidence or something bad happened from it. Also won’t make the sound when rolling down the road in neutral, just at idle after 100F and rolling at 0-50mph u can hear it clearly.