Rotella T 15w40

[Drivin' Miss Daisy]

Hello all,
I am the proud owner of a 1985 c10 with 150000+ original miles on it. I recently switched from using 10w30 to using Rotella T 15w40 and saw an increase in my fuel mileage jump from 10 city and 13 highway to 14 city and 17 highway with no other adjustments made. I don't know if anyone else has experienced this but with gas prices as high as they are and everyone trying to find a way to help the hurt, it might be worth a try. I did some research and Rotella T meets the API service specifications for our trucks.

As a footnote, in my original 85 owners manual 15w40 is a recommended sae viscosity grade in the temperature range of +10 F to +100 F and beyond.

Just thought I would pass my experience along for those who may be interested.

Darryl