The study examined methods for determining the friction coefficient in metal forming processes, using a universal friction testing machine for this purpose. An assessment was made of the feasibility of determining the friction coefficient by this method for cold tube rolling in cold pilgering mills. The studies were carried out for two versions of cooling lubricants: No. 1 — emulsion, machine oil + water (50/50 %); cooling lubricant No. 2 — composition of cooling lubricant No. 1 + complex lithium grease containing 1.5 % nanodiamonds (50/50 %). During the experiments with cooling lubricant No. 1, we obtained the repeatability with a high degree of reliability. The recommended friction coefficient value for cooling lubricant No. 1 is λ1 = 0.13, which falls within the range of friction coefficients reported by other researchers for this metal forming process. Experiments conducted with cooling lubricant No. 2, when reproducing the test, showed that the resulting dependence diagrams exhibit a completely different pattern of friction coefficient variation as a function of test duration, explainable by the segregation of nanodiamond additives, which is difficult to predict when mechanically adding a plastic grease modified with nanodiamond additives to the cooling lubricant No. 1 followed by mixing, but hereby, the initial friction coefficient values across different diagrams differed by no more than ± 2.150 % and lay within the range of 0.263. Thus, the method for determining the friction coefficient developed by the authors is also applicable to cold pilgering.