I need some help setting up an oil range calibration. The state requires TEPH DRO as C11-C28 and is about to request adding on TRPH C29-C35 which I guess to be motor oil or maybe hydraulic oil. Up till now I have not needed to quantitate motor oil. What is a good motor oil brand and weight to go with for the C29-C35 range?

I have an expired SAE 30W Motor oil standard that I am going to dilute and run tomorrow.
AccuStandard FU-018-H-40X 20mg/mL in hexane

For DRO, I'm currently shooting 5uL per shot so my MDL is 25 ppm and max cal is 50,000 ppm. I'm thinking I should make the ORO calibration separately and then run either calibration separately for reporting. This because mixed sample types have overlap between the DRO and ORO ranges. How is this overlap typically handled? Any suggestions would be welcome.