Seems like my fuel mileage dropped about 2-3 mpg since I switched from Mobil 1 5W40 to Chevron Delo 400 15W40. I am going to change the dino out at 7K and switch back to Mobil 1.

Anyone else noticed anything similar?

I started out the first 18K miles with dino (Rotella), switched to Rotella T synthetic and now Mobile 1 turbo diesel the last 2 oil changes. I figure out mileage every tank and only with the change of winter/summer diesel have I noticed a mileage change. The last 2 tanks of fuel I have gotten average 17.2 mpg which is a little unusual for the winter blend fuel but it too early to say it is because of Mobile 1. Today while at Wal-Mart, I noticed the 2.5 gallon of Shell 15W-40 for $24. I may end up goijng back to dino even though I like the cold starts with synthetic. For the price I pay for Mobile 1, I could do 2 oil changes with the dino. I normally change the oil at 3-4K which is crazy using synthetic but it gives me peace of mind.

once again ...schaeffers oil...if you liked mobil 1 then you will love this stuff

Synthetics have a lower coefficient of friction, which should theoretically decrease workload and help increase fuel mileage. Engine oil itself is usually very small. It's when you switch to synthetic tranny fluid and gear lube that you see the most improvement, if there is going to be any.

I started out the first 18K miles with dino (Rotella), switched to Rotella T synthetic and now Mobile 1 turbo diesel the last 2 oil changes. I figure out mileage every tank and only with the change of winter/summer diesel have I noticed a mileage change. The last 2 tanks of fuel I have gotten average 17.2 mpg which is a little unusual for the winter blend fuel but it too early to say it is because of Mobile 1. Today while at Wal-Mart, I noticed the 2.5 gallon of Shell 15W-40 for $24. I may end up goijng back to dino even though I like the cold starts with synthetic. For the price I pay for Mobile 1, I could do 2 oil changes with the dino. I normally change the oil at 3-4K which is crazy using synthetic but it gives me peace of mind.


I haven't noticed much of a change in mileage with syn vs. dino either but cold starts are easier.

And watch out for those 2.5 and 5 gal of Rotella. They actually cost more:eek: than the single gallons. Take the price and divide it out. The gallons are really cheaper by more than a few cents. Atleast at my wal-mart.

The fuel economy is most effected on people who live in cooler climates and drive short distances. Since synthetic flows better at low temps, it will provide better milage if you typically don't drive far enough to warm up your engine. Otherwise, you won't notice much if any difference.