I would follow through with the recommendation of the oil anaylsis. I use Amsoil oil analysis kit. M preference, you can as mentioned find one doing a search. We used OA program in the Army. I had a large motor pool and we had to change th eoil out maybe 4 or 5 times. This was mostly due to driver error....not securing the new airfilters..high silicia content. It will take more than one analysis to tell you how your engines are doing; the first will be your baseline. From then on you can trend metal particle content and judge your extended oil changes from there.
Color is not a manner of judging oil quality, nor is rubbing a tad fomr the dip stick between the fingers. Particles of 5-10 microns can still damage engines so if your into long care for your engines OA is the way to go......best regards..........LH