Originally Posted by geebee
My rig is identical to yours, only 1884. It's a P-30 chassis, but you probably already know that. It has 82K miles and I've put on about 22K in the 16 years I have owned it. I put ZDDP in with the oil to spplement the the Zinc they no longer put into todays oil. Since we don't have Catalytic converters there is no proplem.
Just thought I'd pass that along.
Just ran/completed a test on "Delo 400 LE 15-40" and all is perfect.....
Delo has 1300 ppm of ZDDP.
Old oil in use was "Royal purple" 15-40 which is a very good oil also, Through the high desert heat (above 110º) the Delo never varied except when the RPMs did.
At cruise (58 MPH-2800 RPM) the pressure remained at 49 PSI and the idle pressure was 39 PSI, Driving over the hill into Redlands which was 25º cooler the oil pressure increased to a steady 51 psi and remained that way until I stopped in Anaheim hills RV park....
Delo is sold at Walmart..