What we did in the service, if you were posted to a place like this and needed a personal vehicle, which the service would often NOT pay for shipping your vehicle overseas, folks would just buy a local junker and then sell it to the next serviceman coming in to replace them.
Sorry, I know thats like telling you to close the barn door after the horse has left.
I would worry about the fuel, when I was in Iraq I saw several brand new American Vehicles rendered useless by contaminated local fuel. And it was more than clogged fuel filters, it was damage to the fuel system and engine. Catalytic Converters can suffer a lot of damage and clog as well, from the impurities and especially any lead compounds in the fuel (a lot of foreign Nations were using leaded fuel long after the U.S. banned it, NOT sure if that is still true today).
At the very least, I'd look at changing your fuel filter, and sadly, because American Fuel standards are so high now, all the manufacturer's have switched to lifetime fuel filters that are much harder to change, like drop the gas tank to change them.
Dusty conditions means changing oil more often, the dust does work it way into the engine and into the oil. If you have to change filters every 2 months, you should be changing oil very often.
You immediate problem
, you're way overdue for an oil change. And you have to decide if running on bad oil of the correct viscosity is better than running on new oil of the wrong viscosity. I don't know how bad the MDS of the Hemi reacts to the wrong viscosity, that is the big "IF" here. BUT we do know running to long on bad oil will ruin your motor,
so your going to have to change it eventually or your going to end up worse off than the MDS NOT performing up to optimal levels.
- If you can find Conventional Oil of the right viscosity, use that, just change it more often, like every 2-3k miles.
- If you can find Synthetic Oil that is thinner but closer to the right viscosity, I use that and change it more often.
- If the 10W-40 is the only oil you can get, definitely get synthetic over conventional (synthetic flows better for the same viscosity as conventional so it likely will act closer to a lighter oil when flowing through the MDS plumbing). To offset the heavier weight, I would make sure you idle the cold motor for 2 or 3 minutes or even more, after starting cold before driving, it will really only offset the cold viscosity when the oil is cold by warming it up before driving and engaging the MDS.
Spark Plugs, a lot of the newer ignition systems have proved finicky on plugs for some people, seen posts (on this and other forums) that folks switched brands or types of plugs and got symptoms of worn out plugs and it didn't go away till they switched back to the exact OEM plug by part number. For that reason I stick to the exact OEM plug by brand and part number.
The problem with Platinum and Iridium plugs with the newer ignition systems is usually if the newer ignition system is a "Wasted Spark" or "2 plugs share 1 coil" Distributorless Ignition System (DIS). In DIS ignition systems, if they decide to share 2 plugs on one coil, one of the two plugs has a reverse current flow. That reverse current flow reverses anode/cathode on the electrodes on the plugs and in the case of Platinum or Iridium plugs that have different metals between the anode/cathode, you've just reversed the effect of slower eroding to faster eroding electrodes. This is why they developed Double Platinum Plugs that has platinum on both electrodes for the Ignition Systems that have reverse current flow the plug can handle it and NOT errode away faster than regular plugs.
- So determine what Ignition system your HEMI has, does it share more than one plug per coil? If it does, then I would use the exact brand and part number for the plugs as OEM. If you only have 1 plug per coil, then you can experiment with other plug types and thoeretically shouldn't run into a problem.
My 2010 3.7L is a "Wasted Spark" system, my brothers 2007 3.7L (Grand Cherokee), although the engines are identical in every way, has one coil per plug. I might be cost savings, it could be emissions, the wasted spark fires on exhaust and power stroke, so it does offer some improvements in burning any HC in the emissions.
Brakes, shudder or pulsating pedal is often wapred rotors or bad rotors, replacing pads may help but if the pulsating/shudder comes back, its the rotors. But dirt, lack of lubrication, foreign debri between pad/rotor can create those effects also, a good common sense inspection of the brake looking for anything wrong and fixing what you find, might help.
With modern brakes, you can sometime get the rotor hot enough it effects the metalurgy on parts of the rotor, you get hard spots or different temper spots, that creates the shudder that can dampen out with heavier brake force. When it happened to my mini-van, the pad that swept the surface with the hard spot would NOT wear evenly, it will wear faster on one edge so the pad would always tilt in relation to the rotor. It did NOT go away when I had the rotors turn (the hard spot extends lower then the surface) it only went away when I got new rotors.