I made the decision to switch to Amsoil synthetic from Delo and luckily right before I left for a 1700 mile trip to Texas the oil arrived. So at the last second I did an oil change(Amsoil 15w40 severe and Strata filter) and here's a couple of observations:


1) The engine seemed to run a little cooler. With the delo I ran slightly over 200 deg., and with the Amsoil synthetic I run slightly under 200 dreg.
2) Fuel mileage definately increased by ~.5 miles to the gallon, I'm not sure if this is related to the engine running cooler.


Also on another note, I run the Power Sevice/MMO mixture(12oz+4oz) and the fillups without the additive seemed to get almost .5 mpg less than with the additive.

Anyone else have the same things happening with mileage or is it the fresh air in my tires?


BTW, the stretch of highway between Junction TX and El Paso TX is great for testing such things. That is one big axx state.

 

I just did my whole truck with Amsoil at 10,000 miles. Everything....Diffs,tranny, air filter,transfer case and engine oil. I used the new 5w40 that came out.The start up in cold weather is truly amazing. The biggest difference I have noticed with the Amsoil is how smooth the truck rides. Definetly a huge difference over stock fluids. It's the only stuff i'll ever use in my truck!

 

Did the tranny fluid make the shifts any different? Sometimes I get a wierd shift.


thanks

 

I bet it's the cetane boost that is in the PS that's getting you some of the extra MPG's

I also saw MPG increase with Amsoil in my 01 CTD

 

Yes, the tranny seems to shift smoother than before.

 

My 99 came off the lot with standard fluids and oil in everything. I drove approx 20,000 miles and changed the engine oil, front axle, rear axle, transfer case, and 6 quarts in the transmission to amsoil at that time. I never seen any MPG improvement nontowing or towing. The only MPG improvement came from when I hit right around 70,000 miles.

 

I have tried many different additives, and the MMO/PS mix was the least effictive. Mileage was the same as without an additive, and ran about the same.