Originally Posted By: clatterpillar
i am trying to complile a list of reasons as to why my boss should stop using 15w-40 rotella diesel oil in our entire fleet.
we have 6 medium duty IH dump trucks, several cat backhoes, and about 80 gas pickups; mostly 2010+ ford f250s, with a few dodges, and chevys mixed in. we also have a few "passenger type" vehicles; ford escapes, ford station wagons, jeep libertys/grand cherokees, etc. we also have two ford hybrid cars (i forget what model). all vehicles are gas, except the dump trucks/equipment. 99% of them call for 5w-20.
using 15-40 in them cant possibly doing them any good, can it? these new engines are not the same engines made in the 80s. we have several pretty new trucks that have serious bottom end knocks/valve train noise. my boss thinks this is totally normal.
i was dumbfounded when i first started working at this job, and was pouring 15-40 into dodge neons. our fleet is plaged with oil leaks, low-hour engine failures, low-hour major component rebuilds, and general un-reliability. *i* think alot this stems from their "one oil fits all" approach. we only use one engine oil (15-40), one atf (atfII), and one gear oil (80/90). nothing in the fleet calls for atfII, or 80/90. yet we spend $28/gallon for some gimmick synthetic hydraulic oil.
am i over thinking this, or am i on the right track?
I don't think using 15W-40 would cause damage to the engines, even if they call for 5W-20. But you will experience less fuel economy and horsepower. Regarding 15W-40 decreasing the engine life in gas engines, it's hard to say. Also, you might have difficult starting and even engine damage at very cold temperatures.
For heavy-duty diesels, even a CJ-4 10W-30 is a no-no. These engines require 15W-40, period. You could use 5W-40 but nothing less. Even a CJ-4 10W-30 would cause a lot of wear on these soot-coughing beasts, as the thinner oil film cannot cope with the abrasive soot particles.
Another problem with using gasoline-engine oil in fleets is that dino PCMO won't work with fleets and you need synthetic PCMO or dino HDEO. Both dino HDEO and synthetic PCMO allow longer oil-change intervals and harsh driving conditions but dino PCMO is a no-no for fleets.
If you want to switch from 15W-40, these are your choices:
(1) Switch to 5W-40 synthetic CJ-4 HDEO for all your fleet -- it will solve your problem during very cold temperatures. Shell Rotella T6 5W-40 or Chevron Delo 400 LE 5W-40 are not expensive.
or
(2) Keep the 15W-40 HDEO for heavy-duty vehicles and switch to a cheap 5W-30 fully synthetic PCMO for gasoline engines, such as Formula Shell fully synthetic 5W-30 or similar.
I would recommend against dino 5W-30 PCMO in fleets. It won't allow you long OCIs and harsh driving conditions. I would also recommend against 5W-20, unless all your gasoline engines call for it. It could be too thin for some engines and cause excessive oil consumption and tailpipe smoke. Note that dino 5W-30 also shears down to 5W-20 after a short time.