In regards to why Fedex and UPS shut their engines down, I think the reasons have nothing to do with oil. Has more to do with theft of the truck and liability issues. Ever notice the postal delivery people? Every time they step out of their vehicles, they set the brake, put it in park, and turn the engine off, even if only for a few seconds. That's because of liability.

If you stay with the vehicle all day long like the taxi fleet and police do, then by all means let the engine run. That's why the taxi fleet can put over 300,000 miles on their engines without blinking.

 

Come to think of it, the local cops hardly ever shut their Crown Vics down, unless they are out of sight of the vehicle. I have seen them at accident scenes idle them for hours, A/C running etc. However, a Taxi has to be moving all the time in order to be making money. I doubt they idle as much.

Wasn't it Havoline the cops cars ran so many hundreds of thousands of miles on, in that old commercial?

 

I'll summarize this way, and see if labnerd will agree. I see no problem with running straight weight in your circomstance, and you won't have the polymers in the oil, BUT, you also won't have the other additives that you want. Those additives make today's oil better, allowing it to protect your engine better.

 

What wouldn't it have? I have been doing some research, mostly on the net and am finding interesting things. Example, a lot of utility companies run straight weight oil in their trucks, simply because they do idle so much of the time. Most specify a heavy duty, detergent type 30 wt. Some are brand specific, some are not. I think however, that I may still try the Chevron 10w30 supreme. I noticed during my readings, that a lot of companies with fleet vehicles that idle a good deal, specify that as well. SBC for example (phone company.)

Side note, off topic. I found very interesting the fact that virtually all NASCAR teams run 5w30 Mobil1, regardless of what the decal on the car says. That F1 and CART teams all run Mobil1. 10w40 for CART, 20w50 for F1.

I guess there is something to be said for both multi-weight and straight weight.

 

When I got my petrochemical degree, additives was an elective which I chose not to take.

You present a good case though. The thing about fleet vehicles is that the objective is to minimize costs on vehicles you own, but don't have to drive. A lot of different oils use the same base stock and used additives to make their specific brand. The additives raise the cost of the oil. Any oil that meets the specs for your vehicle will have no problem lasting 3000 miles in typical driving conditions. Your's being non-typical driving conditions, based in hours rather than miles, do all the rules which apply to 3000 miles also apply to 100 hours?