For the many engines I've used Synthetic in, no difference in MPG.
Take care, Bill
Take care, Bill
How does synthetic yield better gas mileage?
- Thread starter Bill in Utah
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I'm trying to decide between DELO 15w40 dino vs. Rotella T synthetic 5W-40 for my 97 Mercedes E420 (105k miles). While reading up on the Rotella Synthetic, it said that it offers improved gas mileage compared to dino HDEOs? how?
While the synthetic is warming up it is thinner. After it is hot the two oils are about the same. It is enough for them to make the claim of better mileage.
Be sure to get your cam chain checked in that Mercedes engine. I think that chain in that engine is 7 foot long and if it breaks...bad news.
Be sure to get your cam chain checked in that Mercedes engine. I think that chain in that engine is 7 foot long and if it breaks...bad news.
Basicly Synthetic oils have traditionally had a higher viscosity index than conventionals, The higher the VI the less the oil thickens as it cools. Today the viscosity index is getting better for all oils so the difference in the warmup phase viscosities is getting to be less but a difference remains.
Here is a graphical representation of what the others are saying. Depending on how cold your oil is, the 15w40 will be much thicker than the 5w40 at the same temperature.
You can see that at around 0 degrees F, the viscosity of the 5w40 is about 3000 cSt vs. 10000 cSt for the 15w40.
Many thanks to Rich Widman for the new viscosity graphing toy!
You can see that at around 0 degrees F, the viscosity of the 5w40 is about 3000 cSt vs. 10000 cSt for the 15w40.
never really "SEEN" MPG increase. want better mpg? lighten the vehicle up 500#'s and accelerate slower.
I believe it takes a total makeover package to get better mileage. What I am talking about is a total drivetrain fluid replacement to synthetics.
Synthetics are known for less resistance needed for an engine/drivetrain to do the same thing as dino.
It would be like waving your arms underwater and then waving your arms under jello. Of course I am just giving you an example. Why do the new SM oils get better mileage? Less friction/resistance like synthetics.
Synthetics are known for less resistance needed for an engine/drivetrain to do the same thing as dino.
It would be like waving your arms underwater and then waving your arms under jello. Of course I am just giving you an example. Why do the new SM oils get better mileage? Less friction/resistance like synthetics.
I'm not sure the "official" reason for this. However, FWIW here's my theory of what is going on:
It's been my experience that Synthetic oils are generally a bit "slicker" than dino oils. And so (at least in theory) they result in less engine friction (and many of us have noticed more "engine power" on synthetics, so this sounds plausible). Since friction is essentially engine drag that isn't doing anything useful, lowering the friction should allow slightly more of the engine power to be put to more useful purposes (such as moving the car forward). Therefore you need a little less overall power (and therefore a little less gas) to get the same "useful work" done (as you are wasting less of the total energy on friction drag)...
As others have said, there's no significant difference at operating temperature, but a bit of an advantage during warm-up.
I also have seen no difference between dino and synthetic on fuel consumption. I did see a slight decrease in fuel economy when using MaxLife Synthetic after draining out Mobil 1. I think MaxLife is a little thicker, even though both were 5W30. PP 5W30 weems to act the same as Mobil 1 5W30l.
What you are seeing is the differnce between "energy conserving" 5w30 and 5w30 that is not energy conserving. The difference is due to the higher viscosity with the ML syn.
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The more refined one gets the dino themore uniform the molacules. SO a group III is going to have a much more uniform molecular size. GIV adn V oils are completly uniform. Now you are probably woundering how this answeres your question? Well if you are trying to make someting spin or slide would you rather have all of the ball bearings the same size or random sized? Now I do not know enough about GIII wich is what RTS is made from but with GIV adn GV base stocks the oil itself has different frictional flow chateristics then dino. What I mean is that the oil behaves differently then dino as it pass's over parts kind of like the difference between laminar airflow v.s. non-laminar airflow. THis is when a picture would be worth a thousand words. Seeing how winter is not far away I think that your interests would be best served by RTS 5W40.
I was looking for the word molecules and last post had it, yours, good explantion...
if I may add molecules the same size slide past each other much better than mineral oil molecules wich are all different sizes
I've used various brands of 10w30 dino oil, 10w30 Mobil 1 and 10w30 HDEO....and the car gets the same gas mileage.
The way you drive your car has a greater impact on gas mileage.
The way you drive your car has a greater impact on gas mileage.
Synthetic oil is slippryer and has better pumpability.
Takes less engine power to pump it and it does reduce friction.
In the end though, some engines might get better mileage with it, others won't.
Mine does. 1 or 2 mpg better, and longer drain intervals.
Takes less engine power to pump it and it does reduce friction.
In the end though, some engines might get better mileage with it, others won't.
Mine does. 1 or 2 mpg better, and longer drain intervals.
I really would like to see the definition of slippery in terms of motor oil, and the results from the "Energy Conserving" tests that show synthetics providing lower friction despite meeting the same specifications.
"slippryer " ???
And what kind of "synthetic" do you think is "slippryer"
Again. Oils that thicken less when cool have less friction due to the flatter viscosity curve during warmup.
Some examples of 40° and 100° viscosities in a few brands of 5w30 @ 40 and 1000°c respectively
Tropartic- 64,10.9
Mobil 1- 64.8,11.3
Pennzoil Yellow- 63.9,10.5
Pennzoil Platinum 57.5, 10.3
Valvoline AC- 61.98, 10.46
Valvoline Synpower- 60, 10.3
Castrol Syntec- I would post but they play trickey Dickey with their PDS system.
Plug these items into the Widman chart to get a viscosity curve if you wish..
And what kind of "synthetic" do you think is "slippryer"
Again. Oils that thicken less when cool have less friction due to the flatter viscosity curve during warmup.
Some examples of 40° and 100° viscosities in a few brands of 5w30 @ 40 and 1000°c respectively
Tropartic- 64,10.9
Mobil 1- 64.8,11.3
Pennzoil Yellow- 63.9,10.5
Pennzoil Platinum 57.5, 10.3
Valvoline AC- 61.98, 10.46
Valvoline Synpower- 60, 10.3
Castrol Syntec- I would post but they play trickey Dickey with their PDS system.
Plug these items into the Widman chart to get a viscosity curve if you wish..
I recall seeing a test on one of the automotive shows on either Speed Channel or SPIKE. They put a car on the dyno, measuring horsepower with dino fluids in the car. Then after replacing engine oil, rear end and maybe transfluid (not sure) with synthetic fluids (I think they used RP) the dyno showed around a 5 hp gain. Does this prove synthetic reduces friction?
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