Synthetic fluids improve MPG?

[Whitewolf]

Originally Posted By: Quest
given the basic prerequisites RE: ATF fluid to have proper viscosity and friction properties in order to meet a specific transmission manufacturer's requirements, syn based ATF is designed and blended to be of similar specifications (friction properties, viscosity, etc.) in order to be used in that same transmission.

With these 2 properties in-mind, I don't think you'll gain MPG (if any).

The only benefit of syn ATF (given all else equal) should be higher oxidation resistance (higher temp), therefore, it should lasts a bit longer(inside the trannie).

Q.


That is incorrect but I cannot say more right now.

 

[wiswind]

For what it is worth, Regarding Toyota T-IV fluid specification.... Red Line recommends their D4 ATF for the T-IV specification in Toyota / Lexus Vehicles.
I have Redline D4 in my 2003 Sienna that calls for Dexron III and I used the same in my '96 FORD Windstar that specified Mercon-Mercon V.

In terms of fuel economy gain, remember that a 10% gain on 25MPG is 2.5MPG gain.....
In other words.....don't expect get a 5mpg increase on your switch from one fluid to another.
How much of a gain you will see is going to depend upon the fluid that you have in there.
The synthetic, in theory, will not break down as fast, and will give you better performance over the term of the time it is in there.

It is important to use a fluid that meets the specification that your vehicle calls for.
Some fluids are licensed for the specific specification, others say "recommended for" or some other language that indicates that it may not be licensed for the specification.
In the case of not being licensed, you are trusting the company selling the fluid (Mobil, Redline, Amsoil, Valvoline....etc)
I trust the company that has their name on the bottle (Redline) for the fluid that I buy....and certainly many other major brand names could also be trusted.
A fluid that does not meet the specifications could do more than harm your fuel economy, it could cause damage to your transmission.

In terms of fuel economy, the biggest 2 things that you can do are to keep on top of the routine maintenance (timely replacement of the ATF is on that list), and driving style.

 

[Doug Hillary]

Hi,
HFSS_TR - In this case any product meeting the required specification is all that is needed. Paying extra money for "high quality fluids" is typically not justified

 

[HTSS_TR]

Thanks Doug.

 

[meep]

in rwd cars/trucks I have seen .5 mpg increase per axle. that is not .5%, that is .5 mpg. doing my 2wd jeep with amsoil 140wt in the tail and castrol ATF+4, thinnest vis next to amsoil, I came close to 1.5 mpg average on my easy commute (45-50 mph, minimal lights, etc.).

Similar with 97 pathfinder.

Similar with 93 Jeep GC.

Syn fluids in fwd honda or chrysler minivans (2) ... no measurable change.

I have never had a measurable change with syn engine oils, though I continue to use them for longer intervals.

M

 

[Capa]

What is so interesting, Doug, is that with your extensive testing with fleets, you saw a benefit using synthetic oil but no benefit with synthetic fluids.

 

[Doug Hillary]

Hi,
Capa -
Originally Posted By: Capa
What is so interesting, Doug, is that with your extensive testing with fleets, you saw a benefit using synthetic oil but no benefit with synthetic fluids.


Capa - Oils and fluids. For Thread this we'll call engine oils EOs and those lubricants used in gearboxes and diffs GOs. ATFs are those lubricants (fluids) used in an auto transmission or other specified applications

EOs - I have used synthetic engine oils for about as long as they have been available. This started with Castrol's ester racing lubricants in the 1950s. Unless specified by the engine manufacturer the benefits of their use IMO accrue in the possibility of extended OCIs and in some cases better contaminant handling and perhaps longer life due to better viscometric possibilities.

They should always be monitored for cost effectiveness!

GOs - In the correct application there are considerable benefits in using sythetic GOs. I have used these since the 1960s.

The benefits vary according to the application but in a general sense they considerably extend seal (and consequently wheel bearing) life amongst other things. Operating cooler they have benefits in extending component reliability and overall durability. This especially applies to heavy vehicles with tandem (interaxle diffs) and those with diff locks operating in extreme conditions.

With non synthetic GOs high levels of oxidation typically resulted in high acid levels which lowered OCIs considerably. Significant increases in viscosity was also a problem!

In my experience a move from the OZ Road Transport Industry "norm" of a mineral 85W-140 to a synthetic 75W-90 was a prime factor in extending durability - providing better cold flow and better high temperature cooling. Average temperatures were from 86C-94C with synthetics against a permissible max of 150C and an expected operating range up to 120C

One considerable benefit was lower cost - "lifetime" OCIs against 200kkms!

Multispeed 13speed> constant mesh and synchromesh gearboxes also perform better with better shift quality and lifetime OCIs too. These gearbox families had significantly extended shift fork and bearing lifespans

ATF - Where I have used synthetic ATFs in manual gearboxes and transfer cases etc the benefits over "normal" ATFs have been the same as under GOs above. In auto transmissions I have experienced much better shift quality over a "normal"ATF and much longer OCIs- "lifetime" in fact.

I would always use a conforming synthetic ATF in any auto transmission I own

As to measuring fuel economy benefits, the variables overwhelm the possibilities for accurate in-service measurement. Synthetic GOs will IMO however show most frictional resistance benefits (resulting in fuel savings) in inner city delivery vehicles etc where GOs rarely reach a suitable operating temperature