Using heavier viscosity oil to increase fuel economy?
 

Has anyone tried using a higher viscosity oil and saw any mileage differences. I've taken the advice of Louis LaPointe's article on www.lubedev.com and switched the 5w30 oil that my Saturn had that I bought in June and switched it to 20w50 (Walmart SuperTech for testing right now) and my gas mileage has increased. Over the past 4000 miles on the 5w30 the best I could get was just under 38 mpg. With 20w50 over the past 1500 miles, my gas mileage has increased to 40 mpg. Pumping up the air in my tires to 44 psi, this week's mileage is 41.2.

I haven't changed my driving habits and drive this vehicle mostly on the highway. It doesn't burn or leak any oil so I didn't switch to the thicker oil for that and I haven't noticed any power loss due to the heavier oil.

I've tried the same thing in my F150 but instead using 10w40 and achieved the max mpg I got with synthetic 5w30 the first two weeks after changing the oil (22 mpg) . And this was having the cruise control on 64 instead of 59 where I usually keep it. Hopefully I will change to 20w50 this weekend if time permits and see what results I get.

I'm skeptical.

In the quest for improved FE, the goal of changing your motor oil is to reduce friction. The less energy you waste on heating mechanical components (including fluids) the better. So the better the lubricating properties of the oil the better since they reduce metal-on-metal friction.

**BUT**

Friction is not just caused by metal contacting metal. Friction (and energy loss) also exists in fluids. Viscosity measures a fluid's resistance to shear forces. Higher viscosity = more resistance = more energy required to move it around. By definition, a higher viscosity oil requires that your engine use more energy to make those parts move. Higher viscosity oils are appropriate for mechanical components with wide tolerances, but generally are not appropriate for newer automobile engines that are much more tightly machined than in the past. You want to use the grade that is recommended by the manufacturer, as that's what the engineers know will work.

So I don't understand why anyone would recommend higher viscosity for fuel economy. Rather, what you want is higher lubricity, which measures how well a fluid reduces friction between two sliding components. In general, this means switching to a high-quality synthetic of the recommended viscosity which will exhibit more consistent properties over time due to increased resistance to chemical breakdown.

Thanks for your insight. I was skeptical too which is why I tried using the higher viscosity oil. I also plan on trying it on my 97 F150 which currently has 10w40 in it (Always had 5w30 before as per the owners manual (funny, Ford recommends 5w20 now)). I guess the gain in lubricity is outweighing the pumping loss of the higher viscosity oil?

Anyway with no disrespect, isn't this forum for trying new things and sharing new ideas? I'm sure half of the modifications I have read would not be considered a "manufacturer's recommendation".

Trying stuff is wonderful, but keep in mind it's also very difficult to conclusively equate a small change in mileage to a single factor through tank-to-tank testing.

For those who want to read the source, can you post a direct link to the info that suggests using a higher viscosity oil to increase efficiency?

https://www.lubedev.com/smartgas/ultra5.htm

There are also several articles on the lubedev website, which pretty much covers the same tips.

If you tally everything up, the total "percent boost" if you do everything should be 95-195%. That would bring my car up from the stock EPA estimate of 28.5mpg combined to 56-84mpg combined. Going by the raw numbers instead would put me at 49-71mpg So...does that pass the sanity test?

I'm sure some of those things do help somewhat, but I get the impression that not much actual research has gone into their claims. But thanks for the link just the same.

This guys stuff comes up over and over and over agian, mainly his claims with acetone.

Nobody I've seen has ever taken a stock vehicle, and then followed his items step by step and reported results.

His opinion on the heavier oil is based on some lubricity tester he created.

I ran heavier oil in my truck than recomended, things were okay, but at certain points the engine felt held back under acceleration, i'm assuming the crank whipping through the heavier mix was slowing it down. And that's the problem IMO, that even if the cylinder is dragging less due to increased "lubricity" (we're assuming here) then somewhere else there will probably be more drag due to the oil weight.

oil
 

Lighter oil takes less energy. Why would automakers try to put the lightest oil in their vehicles? It is because with a lighter oil, the parts can move more freely. For example: my boss' work truck has 5w30 in it. (Chevy Silverado V-6)

I've run 20w-50 with no change in FE. I agree with Metro tank to tank varibility is a killer. Different cars behave differently but the only things on that site that have worked for me have been slowing down and driving technique. :)

the main thing I can see with heavier oil is that it is going to help the rings seal better, increasing compression in an older engine, from what I've been told, you want to run the lightest weight oil that still maintains oil presure (without a gauge this is hard to do), to light of an oil and it flows out of the bearings to fast, and you loose that cushin that prevents metal to metal contact.

James,

I switched from 5w30 to 10w40 to slow the oil consumption of my Geo Prism. (its got worn valve seals) I never run it low, I was just tired of topping off every 500 miles. I now top off every 2000 miles. But, I am getting better FE also. 31mpg consistently on a certain route as compared to 29mpg before. I think it does something for efficiency if you are mostly doing highway driving.
Since it definitely does lengthen engine response time, it will hurt "city" FE.

so, in this thread we've had confirmation of either "no change" or "slight increase" in FE... Why? this should be looked into a bit deeper i think, and if i wasn't under warranty, i'd try it myself.

I guess I could test on my wifes civic, but she isn't as precise as i'd like, so...

Thanks for your results! I'm not noticing any lag with city driving but do notice the increase in mileage.

I agree! I'm planning on trying it on my 97 F150. Average over the past 25000 miles is 20 mpg. I already have the same brand of oil (Walmart SuperTech 20w50) in the garage. Hopefully I can get to change the oil this weekend. This truck doesn't get driven as much as it used to 100 miles a week vs 500 miles a week. But, I hope to see some positive results, but will take more time to report them since I can go about 500 miles on one tank of gas.

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While I can't speak for other Hybrids, I can tell you that Toyota recommends 5W-20 for the Prius. I just choose to use 0W-20. If it's good enough for 110 MPG over 1400 miles in my Prius, just think what I would get with a good gear lube oil, say 80W-90?:D

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This old guy has been doing mileage research for 50 years....though some things he posts are political or a bit exaggerated. I don't really think too much of the Torco oil...except for the 2-cycle GP7 for the PIB.

As far as adding up those percentages...yea that's a bit overdone also...but don't think you could go wrong TRYING the things he mentions.

The auto companies specify low viscosity oil in order to marginally improvrove their overall company fuel efficiency ratings, so they can comply with the government standards. If heavier oil gave better fuel efficiency in a new vehicle, they would be specifying it. There are a number of things on that website that make me want to laugh (or cry?), such as "NO engine can operate efficiently without some acetone in the fuel".

He also recommends overfilling the crankcase by one quart--the road to main seal failure on some cars.

I think some of his ideas are okay, and found elsewhere, but all in all I would take his info with a grain (cup?) of salt.

I think that any time people speak in absolutes I begin to stop listening to what they are saying.

"We normally overfill the crankcase one quart by adding one bottle of MPZ Magnetic Friction Reducer additive along with one bottle of EAL Engine Assembly Lube that is a slippery supplement without equal on this planet." to quote his site.
It is nonsense like this that makes you doubt everything he says. The acetone info has been debunked quite thoroughly, too, at least to my satisfaction.

His website comes under the category of "It's on the internet, it must be true".

So who is willing to test?

I plan on it.
This is what I am going to use on our vehicles:
1992 Saturn SL1 20w50 Walmart brand (2000 miles driven on this oil so far)
1997 Ford F150 4.6L 20w50 Walmart brand (Solid 20 mpg over the past 25000 miles)
2003 Honda Odyssey 5w40 Shell Rotella T synthetic (19 mpg combined city/highway for past 43000 miles)

Quick update!
Changed truck and minvan oil on Saturday. First thing that was noticed was a quieter running engine.

Drove 100 miles on the truck so far. Too soon to really tell, but it looks like it is helping (don't know how much).

Honda, wife and I are really seeing a difference on this first tankful. 150 miles driven so far and needle is definitely higher than where it normally with this amount of miles.

Will give an update every tankful with each vehicle.

I have a question for jamescartagena, and anyone else who is going to try running thicker oil, how many miles are on each of these vehicles, what is the engine compresison with thin oil, and what is the compression with thicker oil, and how does that compare to what the compression should be? I only ask this because if it's an older vehicle with worn rings, it would only make sence that thicker oil would increase compression, and give better mileage, thus useing thicker oil might not work for people like me who run 0W-30 on an engine with 225,000 miles and 180psi compression acrose all 4 cylenders when the ideal compression for my car is 185psi, and I've seen them run fine with compression as low as 120psi, but at that point, thick oil is when it really helps.

97 Ford F150 - 122,899 miles
92 Saturn SL1 - 123,350 miles
03 Honda Odyssey - 44000 miles

Never run a compression check against any of them (don't have a compression tester as well), but if oil cleanliness is any indication of ring seal quality, the oil all three vehicles only starts to turn brown after 3000 miles. In 25000 miles of driving, the truck has only used 3 quarts of makeup oil, and the Saturn after 4000 miles needed 14 ounces.

Hmmm.... "Flowing out" faster means what? If it flows out faster, mustn't it also flow in faster to replace itself(after all, this is a hydraulic system!)? And, flowing faster ... in and out ... means better cooling! Cooling is the 2nd job of the oil!
Plus, when the engine is first started...the oil is cold ... and thick! Oil pumps don't like thick oil (the little pressure relief valve opens!)...narrow spaces don't like flowing thick "coolant"! It's the FLOW of oil, not the pressure which lubricates! No flow=no oil=no lubrication! ALL weights of oil are thin when hot! 5-w-30 is fine! "Hot" 30 weight is like "hot" 60 weight...they will both flow! Cold is another matter, entirely! Ever hear the expression "95 % of engine wear occurs at start-up"? Hmmm.... I wonder why?

Pumping oil pressure is a power losing operation. Unfortuanately the Synlube in my xB engine is 20w50 rated and not the 10w30 called for but I still see higher mileage and will not be worrying about heating the oil up too much. But I don't rev the engine too much when cold either or else the oil pump bypass kicks in as it can also work the oil filter extra too.

OPPS and a little extra oil in the Lawn Tractor resulted in it blowing into the carb and smoking up a massive cloud of blue smoke and stalling the engine. About 1/4 inch on the dip stick maybe 8 oz extra - drained it out and it was ok.

Right on!!! This nonsense just goes on & on & on! -Ted Hart

So far to date, the Saturn is averaging 38.78 in the last 3000 miles where I where my best single tank before using heavier oil was 37.2. Have two tanks where I have gone over 40 mpg. No data on my truck as I don't drive it enough but I can tell you that the engine is noticeably quieter. Same thing with the Honda.

So far getting 38.89 mpg average for the last 3500 miles. Traffic is getting bad ever since Labor Day so it is difficult to get the same driving conditions I was getting earlier in the summer. Not bad considering it is taking me about 1/2 hour more each day to get to work.

Plan on trying a thinner oil next oil change. Havoline 5w20 (Gets good reviews and UOA's on BITOG)

I think thinner engine oil can reducing restriction with the
internal movements.
New cars can alway use thin oil to get better MPG,
but as for old cars, because the pistons and rings are not
seal tightly as new car,so thicker oil can helps get better
compression, also more power.

Stop playing with your engine oil and switch to Synlube once and for the life of your car you will not have to change your oil again and get better mileage and less wear.

Okay JanGeo, I'll bite.

Can you point to a controlled study that supports the fuel-saving claims of SynLube?

Yeah look at my gaslog graph - read the info in their website - besides right off the bat you save by not having to change your oil again for 100-150,000 miles which should cut your oil cost in half at least and save you tens of hours of time.

I would love to try Synlube but at 32 dollars a quart is the initial shocker for me. Plus I like to change my oil. How many miles do you have on your oil?

Sounds like you have been brain washed by the auto and oil industry . . . LOL
. . . m u s t c h a n g e oil!
Right now 7839 miles and I put it in at about 3800 miles after initial breakin so 4,039 miles give or take a few miles. Level is exactly the same and it looks as black as the day I put it in. Yesterday I bump started it in second gear going about 1.5 mph - it started right up - just popped the clutch out and in again as fast as I could move my foot. Started better this way than with the starter motor.

Ahem - "controlled"? :)

No offense, but the graph proves nothing one way or the other about Synlube. It's of a vehicle which was breaking in, in ambient temperatures that were rising, driven by someone who wants to get good fuel economy. (And is getting great FE, I should add!)

I don't doubt your MPG numbers. I just don't think you can authoritatively say that based on your graph, Synlube raises MPG.

Cost savings aside, I'm really just interested in the FE claims.

I had a look on their site and couldn't find any mention of a controlled study for replacing crank case oil in a passenger vehicle and its effect on FE.

Replacing diff-oil in trucks & heavy equipment with synthetics is different, and known to have a small FE benefit. That *is* mentioned.

I was just curious if you had more information is all.

They say about an 8% increase with the engine lube then the power steering lube was a few percents and the tranny will vary with what was in it originally. Apparently EVERYONE that changes the tranny oil in the Scions sees mileage improvements when they change to a "better" lube. . . I.E. Redline - Mobile1 etc.
One thing I did notice was that the idle gets down to 0.1gph and about 650rpm but after some extended driving around the idle gets higher like about 750-800 and still 0.1gph so yes the engine is still breaking in a little but is averaging about 10mpg more than EPA estimates (33% more).

A concern
 

I hope I'm not too late on this one -- I once heard - no validity, just hearsay - that you're asking to blow-out the seals and gaskets with a significantly higher viscosity than needed. Would the oil pressure increase with the thicker stuff? A guy used to insist on 40W oil for his engines (this was for the old carbed cars). The guy got a newer, fuel injected car, insisted that the 40-weight oil be added, and it blew the living daylights out of the engine.
RH77