Although my 2003 only has 15000 on it , and I drive it mostly on freeways and dont haul but my trailer, and thats rarely.. it smokeswhen I accelerate. Is that normal? And does anyone use synthetic oil and what are the pros and cons? thanks in advance..Dave

 

First is the "smoke" black or white/blue? Black is just a fuel rich condition that takes place till the turbocharger spins up and supplies more air. White or blue is from engine oil being burned in the combustion chamber. Some times this takes place till the diesel engine is fully broken-in, and everything gets seated. If it seems like alot, or continues to grow, take it in and have them check it out.
Synthetic oil, First lets only discuss 100% synthetic oil, anything less is gunk. It is a man made oil that is free of impurities, does not react to temperature swings like conventional oil:It stays more consistent,doesn't get as thick in extreme cold, or as thin in extreme heat. This consistency aids in oiling via pressure and flow. The oil does not "Break down" like a conventional oil would, It not only last longer, but when exposed to extreme temperatures (like those found on a turbo bearing surface) it remains stable, and does not burn or "Coke' the bearing.
Usually with synthetics, friction is reduced which allows parts to run more freely and reduces heat. The reduction of heat and surface tension results in increased life for the parts affected. There are also performance and fuel efficiency gains . I know when I switched my automatic transmission over to synthetic ATF, not changing anything but the fluid resulted in a 35 degree loss in fluid temperature. I found that to be significant.
The drawbacks to synthetic are few, one it does cost more then conventional oil, on average about 3-4 times as much. And you have to wait till the engine is fully broken-in, before you can start using it. With the diesel, it generally takes about 10,000 miles, and I like to get a good tow in there also. On a gas engine usually 3000-4000 mile in enough.