rotella t syn. 5w-40 for dodge cummins

[countryboy9799_99]

I have a 99 dodge cummins with the 24 valve motor. The owners manual says to use 10w-30 from 0 to 30 degrees f. or 5w-30 syn. from -10 to 20. I found rotella t syn. 5w-40 and was wondering if I could use that? Whats the difference between 5 30 and 5 40? I would like an oil that will work down to 20 or 30 below to 40 above. Any suggestions? Thanx

 

[Rebel Rouser]

I'm using Mobil Delvac 1 5W-40 in my '98 24 valve Cummins, which is a full synthetic oil. The major difference between a 5W-30 and 5W-40 would be it's viscosity at 100 degrees C. I personally would only use the Rotella 5W-40 if it could be had for around $12 a gallon. If costing anymore than that, then the true synthetic HDMOs like Amsoil or Delvac 1 are a better deal IMO.

 

[countryboy9799_99]

The rotella t syn. isnt a true synthetic?

 

[Rebel Rouser]

quote:

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Originally posted by countryboy9799_99:
The rotella t syn. isnt a true synthetic?

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It's a group III basestock that can be labeled and sold as synthetic in the U.S. Indeed a good oil, but pricewise, if it costs nearly as much as the group IV/V oils, then I'd look into buying those instead.

 

[frankoilman]

I did notice walmart has the Rotella T 5/40 on sale for $11.00 and some change. Not a bad deal, even if it isn't a "real synthetic".

 

[countryboy9799_99]

Thanx guys, I will look into delvac 1 also.