In this work a single cylinder four stroke compression engine when it is powered by Madhuca Indica at different fuel inlet temperatures. The fuel inlet temperatures and kinematic viscosity coefficients were the only parameters which were varied, and the shifts in engine performance must be attributed to these temperature and viscosity variations only. The results obtained are summarized as under:

• The preheating of oil shows considerable improvement at higher loads 75% of full load without preheating 4.9 and with preheating 4.58 and at full load without preheating 5.5 and with preheating 4.38. The improvement in BSEC at 75% of full load is 6.5% and at full load 20% was measured due to preheating.
• At 75% of full load 25.8% Brake thermal efficiency obtained for diesel fuel, 19.9% for Madhuca Indica oil without preheating and 21.8% efficiency with preheating. The raw MI oil without preheating has high viscosity and it affects poor spray characteristics and homogeneity of air fuel mixture.
• In the preheating oil to participate better in combustion resulting lower CO emission than raw oil by 47% at 75% of full load. The CO emission was high for advance/retard injection timing at high loads only.
• The reduction of HC emission is 58% at 75% of full load and 48% at full load compared to without preheating and for that of diesel was 52% reduction at no load and 25% for full load.
• The reduction of NOx for preheated oil is 53% at no load, the reduction of 56% at 75% of full load and reduction of 68% at full load than diesel,the reduction in NOx emission is due to lower air entrainment and fuel air mixing rate with MI oil compared to diesel.
• The smoke increases with increase in load. Raw MI oil without preheating produced Smoke emission of 0.5 BSN at no load, 2.8 BSN at 75% of full load and 4.4 BSN at full load but the smoke with preheating was 0.5 BSN at no load.