Bobcat 600 frame-size models—S630 and S650 skid steers, and T630 and T650 compact track loaders—now use a 74-horsepower Tier 4-Final engine that features an ultra-low-particulate combustion system and requires no diesel particulate filter. Engine-oil-change intervals have been increased from 250 to 500 hours, and a new air-cleaner has a built-in pre-cleaner for optimum engine protection in severe applications. In addition, a new engine-protection system manages engine functions to prevent engine-coolant and hydraulic-oil overheating, but will shut down the machine if temperatures are excessive. All Bobcat M Series features are retained, including a newly designed hydraulic system, new boom arms and linkage, large pressurized cab with increased visibility and lowered threshold, and a choice of controls.