Fuel Savings with Synthetic Oil ?

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I change my new cars to synthetic oil (Mobil 1) at my first oil change at 3,000 miles. After this, I change my oil at 7,500 miles. I have noticed that I get about a 2% increase in fuel mileage when I change my oil from conventional to synthetic. Has anyone else seen fuel savings with a change to synthetic oil ? If so, why don't oil companies advertise this ?
 
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Never noticed a fuel savings going from conv to syn oil, but it has been a long time since i ran conv oil in anything. Now I notice a change from winter gas to summer gas. Winter gas takes about 1.5 to 2 mpg out of my truck.
 
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Mainly because it's rare that you actually save any money when you factor in the increase cost of the oil. The difference you mention could easily be accounted for in temperature change and the switch back to summer blends of gasoline as well.
 

Corvette Owner

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 Originally Posted By: Maritime Storm
Mainly because it's rare that you actually save any money when you factor in the increase cost of the oil. The difference you mention could easily be accounted for in temperature change and the switch back to summer blends of gasoline as well.
While I doubt that other things caused the increase, as it happened EXACTLY when I changed the oil, on that tank of gas, you are right about small savings. I calculated on my Corvette, an increase from 22.5 mpg to 22.95 mpg is only $13.58 over 7500 miles at $2.12 a gallon!
 
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this has been discussed many times in many different places, and IMO and experience, it's all in your mind; meaning, you can make that 2% (or 5% or whatever) happen just w/ your right foot. 2% is too small an increment to say it was because of the oil. in a 30mpg car, that's only a gain of 0.6mpg! you can have a greater fluctuation from tank to tank, w/ weather changes and such. the only way to be for certain would be to conduct a lab test; barring that, you would have to switch someone's car w/o them knowing (so they keep driving like normal) and comparing the data from one oil to the next. btw, I DID switch to syn some time ago, in both my cars, and although I did notice quieter operation, everything else stayed the same. I was able to get a substantial increase in mpgs just by driving more carefully. I went from a 25-27 avg up to over 32 just by driving at the speed limit and shifting sooner.
 
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Since I switched to synthetic last October, I've noted a 2% overall fuel economy increase. During that time I ran Mobil 1, Pennzoil Platinum, and Q-Horsepower. Basically on the interstates I get about 32.5 mpg instead of the old 32 mpg that I used before.
 
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 Originally Posted By: mpvue
this has been discussed many times in many different places, and IMO and experience, it's all in your mind; meaning, you can make that 2% (or 5% or whatever) happen just w/ your right foot. 2% is too small an increment to say it was because of the oil. in a 30mpg car, that's only a gain of 0.6mpg! you can have a greater fluctuation from tank to tank, w/ weather changes and such.
I agree 100%. Any improvement in MPG by switching oils is too small to measure accurately.
 
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Royal Purple and Schaeffer's both advertise increased MPGs and get ridiculed for it by some on this board.
 
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 Originally Posted By: Corvette Owner
I change my new cars to synthetic oil (Mobil 1) at my first oil change at 3,000 miles. After this, I change my oil at 7,500 miles. I have noticed that I get about a 2% increase in fuel mileage when I change my oil from conventional to synthetic. Has anyone else seen fuel savings with a change to synthetic oil ? If so, why don't oil companies advertise this ?
Yes I have.
 
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The biggest savings will come from going to synthetic in a manual transmission and rear end. Now, going from, say, 10W-30 conventional to 0W-30 synthetic might save a fraction during warm up.
 

FZ1

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I went from dealer fill to M1 5-20 and got 2-4% increase. But..........I dunno if the dealer fill was 5-20.
 
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 Originally Posted By: Jaymus
The biggest savings will come from going to synthetic in a manual transmission and rear end. Now, going from, say, 10W-30 conventional to 0W-30 synthetic might save a fraction during warm up.
I had hoped for that in my '96 mazda MPV, a true MPG pig. factory rating is IIRC 12/18. engine is freshly tuned, new timing belt, almost full amsoil (ft and rr diffs, trans, engine, just didn't do the transfer case) and I didn't see any appreciable improvement; mixed driving is still around 15, same as before fluid changes.
 
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I looked back over 20,000 miles of fuel records in the truck...10k miles of old M1 and 10k miles of QS. Both were 5w-30. Both had all seasons/all driving types. Wasn't even .2 difference between them.
 
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 Originally Posted By: mpvue
 Originally Posted By: Jaymus
The biggest savings will come from going to synthetic in a manual transmission and rear end. Now, going from, say, 10W-30 conventional to 0W-30 synthetic might save a fraction during warm up.
I had hoped for that in my '96 mazda MPV, a true MPG pig. factory rating is IIRC 12/18. engine is freshly tuned, new timing belt, almost full amsoil (ft and rr diffs, trans, engine, just didn't do the transfer case) and I didn't see any appreciable improvement; mixed driving is still around 15, same as before fluid changes.
Well, that sucks, lol. I did this in my 1986 F-150 old school NP435 transmission and Ford 9" rear end, and gained probably 2-3 mpg. The stuff that was in it was thick and orange... probably factory fill. But I know it wasn't synthetic, lol. I'm surprised for your case.
 
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 Originally Posted By: Jaymus
 Originally Posted By: mpvue
 Originally Posted By: Jaymus
The biggest savings will come from going to synthetic in a manual transmission and rear end. Now, going from, say, 10W-30 conventional to 0W-30 synthetic might save a fraction during warm up.
I had hoped for that in my '96 mazda MPV, a true MPG pig. factory rating is IIRC 12/18. engine is freshly tuned, new timing belt, almost full amsoil (ft and rr diffs, trans, engine, just didn't do the transfer case) and I didn't see any appreciable improvement; mixed driving is still around 15, same as before fluid changes.
Well, that sucks, lol. I did this in my 1986 F-150 old school NP435 transmission and Ford 9" rear end, and gained probably 2-3 mpg. The stuff that was in it was thick and orange... probably factory fill. But I know it wasn't synthetic, lol. I'm surprised for your case.
perhaps if I used this truck for commuting I might be able to see a mpg advantage, but it's our family truckster, lots of local stop and go. to be fair, mpg wasn't a 1st priority for the syn switch. I was more interested in longer OCIs and winter protection. it runs real well, pretty torquey engine. it is a heavy vehicle w/ only a 3.0 V6, so I wasn't expecting miracles.
 
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