I manage a fleet of 40 vehicles but started with this same company as a tech 10 years ago. Since before I started here through today, our shop has always purchased Mobil Delvac 1300 Super 15w40 for our entire fleet. Until recently it was a mixed bag of gas and diesel engines from 3.6 Rams to Cummins ISB 6.7's and Cat C7's. Today, the fleet is mostly gasser Fords. 2015 and newer 3.5L's (NA), 5.4/6.8L's (2V), and recently a handful of 7.3's (still have a couple 3.6 Chrysler engines though). I've been going back and forth on changing our bulk oil purchases from the Delvac 15w40 to a 5w30 synthetic blend to be more in line with Ford's "manufacturer recommendations" and maybe improve the fleet's MPG's in the process.
FWIW, I haven't had any issues with the 15w40 in any of our vehicles, and we keep them until 200k with a 6k OCI. We're in Central Florida and these vehicles do mostly highway speeds and some moderate idling.
Wanted to gather opinions from the BITOG crowd, as most posters seem to have done a lot of research and are well knowledged in the engine lubrication world. Do you think the move to 5w30 is wise, or should I stick with the "if it's not broke don't fix it" approach with the 15w40?
FWIW, I haven't had any issues with the 15w40 in any of our vehicles, and we keep them until 200k with a 6k OCI. We're in Central Florida and these vehicles do mostly highway speeds and some moderate idling.
Wanted to gather opinions from the BITOG crowd, as most posters seem to have done a lot of research and are well knowledged in the engine lubrication world. Do you think the move to 5w30 is wise, or should I stick with the "if it's not broke don't fix it" approach with the 15w40?
