Will using 15-w-40 synthetic(royal purple) be alright in my truck? I accidently ordered that instead of 5-w-40.

 

I dunno dude....

If it doesn't say that's OK to use in diesels, than I wouldn't use it.

 

I don't know about the synthetic, but I've been using 15-40 Valvoline dino in mine since new.

 

as long as it is CJ-5 (I think) compliant your good. . .

besides I've been useing 15w40 all the time in mine. the 5w40 is good for winter since it is a bit thinner. helps with start-up lubrication during cold temps.

 

As long the oil is CI-4+ rated oil you will be good to go. My self I use Amsoil 5w30 HDD and so far it is holding up better then the Rotella 5w40 synthetic I tried out for one oil change last fall. You also need to make sure any 5w40 oil you use is synthetic and not a synthetic blend as it will not hold up or so Dodge thinks.

Also if you do use the new CJ-4 oil if you burn any LSD you will need to shorten your oil drain interval by up to 50% as it does not hold up well when you burn LSD do to the higher sulfer content. One other thing about CJ-4 oil it is not made to run extended oil drain intervals do to the lower TBN number it has.