I've heard a lot about synthetics and have been told by several people that I should be running an amsoil synthetic in my truck for better mileage and longevity.
Then, my friend (he aint too bright, but he knows a lot of mechanics) got a duramax and told me he heard that synthetics are bad for diesels and they seap past the seals and cause leaks...
So before I dump a large sum of money I have to know for sure. Are synthetics good for the 7.3?

 

I have been running synthetics in my 7.3 for the past six years, I have not found any leaks. The only smoke I see is exhaust when I want to get down on it. other wise i haven't had any problems yet.

 

synthetics, well i know for a fact that it well not harm the diesel. i have done lots of research on the subject. it will improve the miles pergallon and reduce friction allot. but i don't agree with amsoil on how many miles you can go before changing it in a diesel. the oil get hotter and dirtier alot faster than if it were in a gas. your best way to go is using shell rotella-t 15w-40. i've ran it all my life in every truck i own including my 6.0 04 power stroke with 24,000 miles and my 95 7.3 power stroke which still runs great with 372,187 miles on it and in my 97 f-150 4.6 triton with 166,500 miles on it. all the truck i own where bought new and the oil changed on the same day i got them and fill with shell 15w-40 oil. all my trucks never had engine problem and still run strong. that what i run and that's what i recomend for you to run. it some of the best and lots of the truckin compainys use it for that reason.

 

I've been running Amsoil 15w40 for the last 2 oil changes on my cummin turbo, and would recommend this oil to anyone looking to change oil wheter it be gasoline or Diesel. Those Chevys just are not as tight as the Dodge or Ford lol. It is nice because the Amsoil will go 15k miles easily, and all you have to do is replace oil filter after 7500 miles and balance off oil level. Do not be scared. I like the ease of not changing oil ever 3-5 thousand miles. It will also increase economy about 1 MPG