I know kinda stupid question. But in my 05 I have run Delo 400 from Day 1 and now 75,000 miles later I am thinking of changing to Syn either Mobil 1 or Amsoil. So hoping for better MPG possibly. Already average 18 and 14 MPG.

There's no problem switching. The products mix fine. You're still pretty low miles so really no need to flush and you've been doing the keep on it, then it's probably in fine shape. If it's not using or leaking now, then no worries.
If you lean towards amsoil (both are fine products), be glad to help...if you need it.

Go to different oil company places and ask for a product booklet there is some good info in them on syn oils. Years ago I asked SAE for info on the oil and good back about an inch of papers.That binder has about 1 1/2" of papers in it. The gent was very good and said he had some other info that I might be interested in. There would be alot of it on the net on syn oil this will enable you to learn some of the differences and give you the info to make good choices on choices and when you want to change oils and why. Good reading.:D

To really gain any perceived MPG, you'll have to not only switch to synthetic, but also change to a lower grade (viscosity). In fact, you'll get more MPG from moving to a lower viscosity than the alternative.

The pumping losses due to grade differences is much greater than the frictional differences between conventional and synthetic lubes. In other words, moving from a 15w-40 to a 10w-30 will net more MPG than moving from a conventional 15w-40 to a synthetic 15w-40. The "best" savings would be moving from a 15w-40 conventional (such as the Delo) to a synthetic 5w-30 or 10w-30 from Amsoil, Castrol, etc.

But don't get all giddy. The most that Castrol projects you might save in such as drastic move is about 3%? That's pretty realistic; a lot of other claims are way too zealous. So 3% of 18 MPG is a whopping .5 MPG. Heck, just slowing down and driving conservatively can get more than that ... Not that it's a bad thing, but just don't be disappointed when you don't see a huge jump.

To really gain any perceived MPG, you'll have to not only switch to synthetic, but also change to a lower grade (viscosity). In fact, you'll get more MPG from moving to a lower viscosity than the alternative.

The pumping losses due to grade differences is much greater than the frictional differences between conventional and synthetic lubes. In other words, moving from a 15w-40 to a 10w-30 will net more MPG than moving from a conventional 15w-40 to a synthetic 15w-40. The "best" savings would be moving from a 15w-40 conventional (such as the Delo) to a synthetic 5w-30 or 10w-30 from Amsoil, Castrol, etc.

But don't get all giddy. The most that Castrol projects you might save in such as drastic move is about 3%? That's pretty realistic; a lot of other claims are way too zealous. So 3% of 18 MPG is a whopping .5 MPG. Heck, just slowing down and driving conservatively can get more than that ... Not that it's a bad thing, but just don't be disappointed when you don't see a huge jump.

Exactly. I tell people there will be an increase but not to expect the big jump that some people claim. When someone claims 2 or 3 mpg in an oil change I call BS. 3 to 5% is common and realistic. 3-5% in a vehicle getting 16 mpg isn't alot. It could amount to 75.00 a year in a vehicle driven 25k miles per year. That 75.00 paid for the oil and one of the benefits to you is the ability with synthetics to extend your oil change interval further saving you money depending on your OCI and your initial cost of the synthetic you choose and the filter you use.

I do think that Amsoil fluids, in the entire drive train, will make more or a difference !!!!!!!!:D:D

I got Amsoil from front differential to the rear differential...and everywhere in between. Never noticed any mileage increase...but that is not why I switched in the first place.

To really gain any perceived MPG, you'll have to not only switch to synthetic, but also change to a lower grade (viscosity). In fact, you'll get more MPG from moving to a lower viscosity than the alternative.

The pumping losses due to grade differences is much greater than the frictional differences between conventional and synthetic lubes. In other words, moving from a 15w-40 to a 10w-30 will net more MPG than moving from a conventional 15w-40 to a synthetic 15w-40. The "best" savings would be moving from a 15w-40 conventional (such as the Delo) to a synthetic 5w-30 or 10w-30 from Amsoil, Castrol, etc.

But don't get all giddy. The most that Castrol projects you might save in such as drastic move is about 3%? That's pretty realistic; a lot of other claims are way too zealous. So 3% of 18 MPG is a whopping .5 MPG. Heck, just slowing down and driving conservatively can get more than that ... Not that it's a bad thing, but just don't be disappointed when you don't see a huge jump.


Did not see any MPG gain when I went to Mobil 1.

Now the kid's car runs 5W-20 recommended energy conserving oil and gets over 30mpg.

We put 5W-40 in it one time and saw mileage drop below 30mpg - so there is something to what Newt said above.........

:D

Most people who do not track their mileage by hand won't ever notice rthe change in mpg. Its slight and will only be detected by someone who already tracks their mileage by hand calculating it. My DIC is about .5 off on MPG when compared to hand calcs. That might be the total amount as in dnewtons post above that one would find in a change to syn. But as Kodiak said many people don't change for the mileage its just a side benefit however small it is.

I do think that Amsoil fluids, in the entire drive train, will make more or a difference !!!!!!!!:D:D

All synthetic fluids will some difference, but not 2 or 3 mpg.

First of all, the diffs already come with synthetic (the grape juice). So there's no gain there.

The engine will see some, but the real gain, as I had stated, is in moving to a lower viscosity. Perhaps 3%?

The tranny can gain a bit, but with the new models ('06 and up) using DEX VI, which is by nature a thinner fluid, there's probably little to no gain there as well.

That leaves the t-case. It's direct drive from the tranny to t-case input/output shaft, so about the only gain you'd see is the ever-so-slight reduction of friction on the drive chain. If you run engine oil because it's "thicker", you just lost any mpg gain there as well, even if it is "synthetic" engine oil.

So the reality is that the engine is the highest gain point, and it's about 3%, or roughly 1/2 mpg for most of us, if you step down to a lower vis.

Still - it can add up over time. I just want for people to be realistic. Anyone that says that gain 3 mpg from a synthetic engine oil changeover is full of stuffing. To go from 18 mpg to 21 mpg just by changing to "synthetic" engine oil is claiming a 15% gain.

Not in reality, folks.

Not in reality, folks.

Good post

The information that I read years ago one of them was Mobil tests their's showed between 8 to 9 % improvment. One of them was a drive from one side of the US to the other and the difference of fuel used was interesting. In the 50's there was alot of snake oil being sold as syn that wasn't. Some of the immediate benefits with syn is that if flows sooner and doesn't break down with the heat and that with the cold temps. I know with my 93 2500 Dodge the Getrag trans lasted till 276,000 kms with using the Mobil 1 5W/30 oil in it.It did need new bearings when I sold it but there were alot that didn't go anywhere near that long with the conventional 5w/30 oil. Always have been a high mileage driver.:D