time for a oil change in my 2002 ctd 4x4 170000 miles on her trying to figure out what kind of oil to use she has 170000 and i heard it wasent good to switch it to syentihec with all the miles on it so i have so oil brands let me know what u guys/girls think i should use and chime in with other brand if u have any (amalie xlo 15-40) (rotella T 15-40) (delo 15-40) (napa auto 15-40)

 

I use Rotella, but you can use synthetic if you want to spend the money

 

I use Rotella. Most of my buddies use Rotella as well.

 

I run Valvoline Premium Blue. Switching to synthetic wont hurt anything

 

Rumor was that conventional oil would make the seals/gaskets swell and the synthetic would let them shrink back up causing leaks. If this is true on the CTD, I don'tnow.

 

No, it wont do anything to gaskets or anything. Its perfectly safe to use...both on a showroom stock vehicle with 0 miles and one thats pushing 300k miles. Gas or diesel

 

so it is ok to switch to syenthic i was asking because i have always used rotella 15-40 sence i got the truck off the showroom floor but she is getting up in the miles so i wanted to run somthing better like ams or somthing

 

Yes. Its ok to switch to synthetic. Amsoil makes some pretty good stuff, I run their ATF in my trans

 

I noticed yesterday at the store rotella makes a synthetic now. Is it ok to switch from the 15-40 to their 5w 40 sythetic on a 5.9? Or is the the newer sythetic just for the 6.7?

 

Been using shell rotella T 5w40 for the last 3yrs. shell has now made available CJ+4 which is backwards engineered for the older CI-4. The CJ+4 is meant for the new fangled emission controlled engines. It can be used in the older engines without concerns. I use the 5w40 yr round from +30 deg C to -45 deg C, never had any problems starting in real cold weather. I also pull 10k lb equipment trailer for business and summer time pulling 9k lb TT.

If your still concerned about engine oils I suggest checking out www.bobistheoilguy.com some good reading and info on his site, knows what hes talking about!