Assessment of the Impact of Lubricating Oil Contamination by Biodiesel on Trunk Piston Engine Reliability

Abstract

The rheological, ignition, and tribological properties of lubricating oils diluted with biodiesel were analyzed. The flash point tFP, calculated cetane index CCI, density ρ, coefficient of the temperature density change ε, kinematic viscosity ν, dynamic viscosity η, viscosity index VI, and lubricity during a High-Frequency Reciprocating Rig (HFFR) test (x, y, WSD, and WS1.4) and lubricating conditions during an HFFR test (oil film resistance FILM and friction coefficient μ) were determined. The test was performed for the oil mixtures of the lubricating oil of the SAE 30 and SAE 40 viscosity grades, which were diluted with the biodiesel blend (D93B7—diesel oil with 7% v/v fatty acid methyl esters, FAME) at concentrations of diesel oil in the mixture equal to 0% (pure lubricating oil), 1%, 2%, 5%, 10%, 20%, 30%, 50%, and 75% m/m, respectively. The experiment confirmed the existence of clear relationships between the increase in the dilution of lubricating oil with tested biodiesel blend and tFP, ρ, ε, ν, η, and VI, and the deterioration of lubrication conditions. It is recommended to take remedial action even in the case of low diesel oil concentration (<5% m/m) in the lubricating oil due to tFP, ν, and η changes. Simultaneously, the tests showed no significant effect on the lubricity and the CCI. The critical contamination of oil with fuel in the range of 2–5% by weight, as indicated in the literature, still allowed for a certain “safety margin” regarding these parameters. However, when the concentration of diesel fuel in the lubricating oil exceeded 5–8% m/m, the deterioration of the lubrication was expressed by a decrease in FILM and an increase in μ was observed; hence, such a contamination should be considered excessive. When the concentration of diesel fuel exceeds 10% by weight, there is a serious risk of engine damage during operation.

A Quantitative and Qualitative Analysis of the Lubricity of Used Lubricating Oil Diluted with Diesel Oil

“…For all measurement points of the tested mixtures included in the experiment, we obtained boundary friction under test conditions. This was confirmed by the r indicator, referred to in other sources as the FILM parameter [31]. Its high values, determined during the HFFR tests and amounting to > 84, indicate that, during the lubricity measurement, there was no direct dry contact of the cooperating samples due to surfactant adsorption.…”

“…Among the many different methods of evaluating lubricity, three have basically found wide industrial use [30]: the high-frequency reciprocating rig (HFFR) [31], the ball-oncylinder lubricity evaluator (BOCLE) [32], and the scuffing load ball-on-cylinder lubricity evaluator (SLBOCLE) [33]. The HFFR method is utilized in this experiment because many fuel quality standards specify lubricity determined by the HFFR method, which has several advantages over other lubricity determination methods.…”

A Review on Biodiesel Production, Analysis, and Emission Characteristics from Non‐Edible Feedstocks

“…The density of biodiesel is a key physical feature that influences its usefulness as a fuel and how much energy it contains [137] . Hydrometers, [138] pycnometers, [139] and oscillating U‐tubes [140] are just a few of the tools available for determining biodiesel density. A hydrometer is submerged in the biodiesel sample, and its buoyant force is measured.…”

Modeling of Selected Parameters of Used Lubricating Oil Diluted with Diesel Oil Using the Characteristics of Fresh Lubricating Oil

“…It should be noted that the main cause of fuel leakage from the combustion chambers into the crankcase is blow-by. This involves the deterioration of piston rings, pistons and cylinder liners [3], and the fuel injection system, as well as the fuel leakage drainage system [16]. The fuel that penetrates through (along) the cylinder liner into the crankcase intensifies the wear and tear of the piston-ring-cylinder liner tribological system.…”

“…• flash point measurement (PN-EN ISO 2719:2016 [10] and PN-EN ISO 2592 [11]), • measurement of self-ignition temperature (DIN 51794:2003-05 [12]) • oil volatility analysis, initial boiling point measurement, and distillation curve determination (ASTM D322-97(2016) [13], ASTM D5800-21 [14], and CEC L-40-A-93 [15]), • gas chromatography (GC) (ASTM D3524-14(2020) [16], ASTM D3525-20 [17], ASTM D7593-14 [18], CEC L-94-10 [19], JPI-5S-23-2017 [20], and JPI-5S-24-2017 [21]),…”