Re : Delo 500
Hi, biggish... This from my friend -
Chevron Delo 400 15-40 is what I use on all my four stroke diesel trucks and buses I service. It is a multi-viscosity lubricant. It flows like 15 to 40 relative to temperature.
Delo 500 40 is used for older Detroit Diesel engines like the 671 straight - six ......6v92.....8v92...and all Detroits with the old style mechanical governor and injection systems. It is a single viscosity oil. The reason we use 40w in these old engines is that the 40w is a "stiffer" oil. If you use 15-40 in these Detroits the components "float" too freely in the governor because the parts move to freely and the engine has a tendency to surge and have a wandering / searching rpm at idle when the governor is attempting to find its equilibrium. The thicker 40w oil restricts this "sloppy" movement and the governor which controls the fuel rack is more stable in its attempt to find its equilibrium.
It's almost the same thing like using 85-140 oil in some manual transmissions that require 5w 30 oil.......They're hard to shift between gears in cold weather because due to the close clearances the oil becomes trapped between the synchro cone and ring slowing down the time it takes the synchro to bring the next gear to a matching rpm to enable easier shifting. The 5w30 escapes and is squeezed out of the clearances much quicker and the shifting quality is much quicker and smoother.
Hope this helps clear up your curiosity!!
