[Rick Leininger Jr.]

As far as I'm concerned, along with some of the factors already mentioned - piston skirt design, piston oil groove drain back design, oil kinematic viscosity at your operating oil temp, rod bearing clearance, isolated cam tunnel or not - can also impact the minimum oil ring tension or drag required for acceptable oil control.

I use the Hastings flex vent style oil ring in all cases where it is available. I pull the piston/pin assembly with WD-40 and a fish scale I've had for years, and have a backlog of data with. As far as adjusting tension, I'll get smaller or larger bore expanders and adjust as necessary. If I can't get the tension down to where I want, I'll install each oil ring expander with excessively gapped oil rails on an undersized piston, and use a band style ring compressor to squeeze some tension and circumference out of the expander. If I need more tension, I'll stand the expander upright on a flat surface, and press an ever so slightly larger drill bit in between each lug of the expander to increase it's circumference and tension.

Also, each lb. of oil ring tension removed per set is worth ~ 1 lb. of torque at the flywheel.