Thanks a lot for this great help.
What are the differences between diesel and gasoline oil, is it only phosphorous percentage ?
I’m not sure. There’s a forum devoted to discussing motor oil: www.bobistheoilguy.com
I’m sure that has been discussed there. That’s where I got the details on the Rotella T6.
If the engine runs very hot, would a 5W40 or 5W50 be better for that purpose ?
The engineers have a reason for recommending the operating temperature viscosity (the second number of the viscosity spec.) that they do for a given engine, though I know the manufacturers skew their results towards the low viscosity side to help their federal fuel economy numbers, which is why I usually go one step in the higher viscosity direction, especially after the engine has some age on it.
Think of all the important things they consider in the recommended oil viscosity, like normal operating temperature lubrication protection and wear and fuel economy. There’s pretty much a bell curve on those two things - higher viscosity (within reason) is better for lubrication protection and wear, but worse for fuel economy. They are pressured to slightly sacrifice the protection and wear for slightly better fuel economy numbers due to government pressures. I put a higher priority on engine life, so I figure one step higher in normal operating temperature viscosity is putting things more like they really should be (for my personal priorities). But you can go too far in that direction too, and the tweaking of the viscosity I do is a guess with no data to tell me how far is too far in either direction. I doubt 50 operating temperature viscosity will do any damage - I just don’t want to get too close to that end of the scale without really knowing the technical details for the particular engine.
And of course the first
number of the viscosity spec. can be low (like 5) for a synthetic as the oil is going to be more viscous at startup temperatures, and good flow takes priority at cold startup. 0 probably would work too, especially for a colder climate, but, again, there’s a balance to everything.
What about water, can I use standard cooling water ?
I’m not familiar with G12 coolant - is that a European thing? Or maybe it’s a later improvement. In North America, Chrysler says G05, which Some Fords and Mercedes also use.
What model Champion or Bosh spark plugs can I use ?
A lot of experience on the LH car forums says that the Champions are the sweet spot in spark plugs for the 2.7 engine, and NGK or Champion spark plugs are it for the the 3.2/3.5. Several people have attempted to get jiggy with spark plugs and almost always regret it. Usually other plugs just don’t run as well in our cars, but there have been more than one instance of electrodes breaking off into the combustion chamber on some of the Bosch plugs with the real thin ground electrode. Bosch may be an OK brand in general, but Bosch parts (spark plugs and engine sensors) and Chrysler engines just don’t play well together.
For the EGR system, is it possible (technically) to redirect oil vapor to the atmosphere rather than into the intake ?
Do you mean PCV or do you mean EGR? If PCV, you need the intake vacuum of the PCV to actively pull exhaust gases and moisture. The crankcase would be a mess without PCV. If the use of oil concerns you, some people install a small oil trap (similar to oil and moisture traps used on compressed air systems) in the PCV hose. My experience says that if your PCV system is kept in good condition (PCV and crankcase vent hoses clean and not cracked, PCV valve clean and working properly), you don’t get oil usage. However, it’s not unusual for a 2.7 much above 100k miles (150km) to use oil heavily due to bad valve stem seals
. More often than not, replacing the valve stem seals on a high km 2.7 eliminates the high oil usage.
Get the PCV system and valve stem seals in good shape, and there should be almost no oil usage. (Check that oil is not dripping from the oil pressure sensor - replace if leaking - use OEM only for that part.)