Pure plant oil fuels, used in compatible agricultural machinery contribute to sustainable food supply. Especially rapeseed oil fuel significantly reduces greenhouse gas emissions up to 91 % and thus, lowers the carbon footprint of agricultural products. However, despite this advantage plant oil fuels are barely used in practice, because of technical, economical and sustainability concerns of potential users. It is the purpose of this work, to show the reliability, downtimes and the emission behaviour of pure rapeseed oil compatible tractors in practice. As test fuel, cold-pressed rapeseed oil fuel, complying with the national German standard DIN 51605 was used. Emission testing on the tractor test stand is based on the standard procedure of EU guideline 2016/1628. Differing from type approvals, where engine test stands are used, here the measurement is done at the tractors with mounted engines. The power is measured at the power take-off (PTO) with a dynamometer. As testing cycle, the Non-Road-Steady-Cycle (NRSC) and an adapted Non-Road-Transient-Cycle (10sNRTC) are applied. For real driving emission (RDE) measurements, two state-of-the-art tractors are being used. By using a PEMS Semtech Ecostar, which was set up in a box for off-road use, the emission components CO, HC, NOX are measured. Investigation of the monitored 20 tractors (exhaust stages I, II, IIIA, IIIB and IV) for more than 60.000 hours, showed no considerable failures or damages. Generally, the limited exhaust gas components (NOX, CO, HC, PM) determined at a tractor test stand remained nearly at the same level over the operating time. Plant oil tractors with exhaust gas stage IV achieve the legal emission limits with rapeseed oil fuel during both, the NRSC and 10sNRTC. Results of RDE measurements also show that recorded emission values are within expected limiting values for both fuels. Conformity factors that relate actual emissions, measured with PEMS, to corresponding test cycle values, measured at the test stand are within approaching legitimacy.