not all oils are formulated, or priced, the same, however. "If you look at the various suppliers of 5W-40s, virtually all of them are full synthetic oils," says Betner. "Per-gallon pricing is usually upwards of twice." But there are potential paybacks, such as the ability to consolidate your oil, as well as increase drain intervals.
"I have a municipality near Chicago that has everything under the sun in terms of equipment. They were using an automotive engine oil for their automotive fleet and a 15W-40 for the heavy equipment," Betner says. "When they went to a 5W-40, they were able to consolidate."
The automotive fleet is actually getting better protection in severe applications with the higher performing 5W-40 synthetic engine oil. "The heavy equipment turns over beautifully on the cold winter days on Lake Michigan, unlike the 15W-40 that would grind a lot longer," Betner asserts. "That municipality claims they are saving about $50,000 a year on fuel, consolidation and cold weather problems."
Drain intervals can often be extended with synthetics. Betner cites a quarry in Wisconsin that has significantly increased oil drain intervals safely. Oil analysis shows very low wear rates. "The quarry has also eliminated the use of ether in the wintertime, which was damaging some of the engines because the 15W-40 was making cold cranking more difficult," he states. Technicians would get impatient and overshoot the equipment with ether to get it running.
Of course, there are pricing advantages to conventional oils. Since a 10W-30 can be made with conventional base oil stocks, the price may not differ much from your current 15W-40 oils. And you still benefit from the lower viscosity. This includes better low-temperature startability and increased fuel economy.
"However, do refer to your manufacturer's recommendations," says Betner. Make sure the chosen oil is recommended for your ambient temperature conditions.
Clearly, there are still cases where the time-proven 15W-40 is the best lubrication solution. But in many cases, the new generation of oils, including 10W-30 and 5W-40, could provide additional benefits that are well worth investigating.