How much fuel economy difference 5-20 vs 5-30?

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Owners manual calls for 5W-20 which I have been using. Car now has 106,xxx miles and I'm thinking of switching to 5W-30.
It's a 4 cyl. engine which delivers very good gas mileage. What do you think the mileage difference will be if I go with the 5W-30? 5W-20 is syn. and the 5W-30 would also be syn.
 
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Nearly 100% certainty it will be 1% or less. You worrying about it probably affects it as much as the change to 5W30 does
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Originally Posted By: skyactiv
If I had to take a wild guess, about 2/10 of 1 MPG. Very hard to measure in the real world.

Agreed, the difference in mileage will be lost in the 'noise' of measurement error.
 
Is there any indication there is abnormal wear in the engine? Or, is the model's factory oil spec known to be inadequate? If "no" to both, 5w30 is unecessary.
 
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So what I got from the the post is that a not at all old car runs on gas and requires oil. You can decide to either put oil in it, or to put oil in it. Hmmm. I vote oil. Difference in gas will be the tire pressure and distance traveled each time you turn the key. The numbers get better in warmer weather and via versa. Everything else is plucking hairs off polar bears [censored]. Not worth the trouble.
 
To the guys that have replied with an intelligent answer to my question I say "Thank you". To the other respondents that felt it was necessary to reply with a snarky response; I won't comment on your replies. I participate in another automotive forum where the members genuinely try to be helpful and polite to each other. The majority of BITOG members do try to be helpful and it's evident in their replies to posted questions.
 
A typical 5w20 has an HTHS of 2.6-2.7. A 5w30 is 3.0-3.1 unless it's Dexos approved then it is 3.2 for Valvoline Advanced full synthetic, and 3.3 for Mobil Super Synthetic. That's a bit of a sizable difference at the end of the day. I believe that would likely have an effect upon fuel economy. Even from a HTHS of 3.1 down to a 2.6 that is a fifteen percent difference between the two.
 
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You have posted on and off here for the past six years. I bet in that time you've picked up a thing or two by hanging around this forum. I also think you probably know the answer to your own original question and that the answer is 'not much'.

My original response was not intended to be snarky, it just distilled your previously gained knowledge into a singular succinct response.

I think you are more knowledgeable than you give yourself credit for.
 
Not a huge difference, but not as insignificant as the snarky posters want you to believe. The difference in viscous drag in the bearings is on the order of 10-12%. Probably on the order of 1% overall fuel consumption difference, which is difficult to measure directly in everyday driving, because uncontrolled variables cause larger differences.
 
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Originally Posted By: Imp4
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Bingo. The question is....why do you want to switch to 5w-30?
 
Originally Posted By: Imp4
You have posted on and off here for the past six years. I bet in that time you've picked up a thing or two by hanging around this forum. I also think you probably know the answer to your own original question and that the answer is 'not much'.

My original response was not intended to be snarky, it just distilled your previously gained knowledge into a singular succinct response.

I think you are more knowledgeable than you give yourself credit for.


It wasn't snarky it was the honest answer!
 
Originally Posted By: CR94
Not a huge difference, but not as insignificant as the snarky posters want you to believe. The difference in viscous drag in the bearings is on the order of 10-12%. Probably on the order of 1% overall fuel consumption difference, which is difficult to measure directly in everyday driving, because uncontrolled variables cause larger differences.


Like many things on here, you'll have blanket answers as gospel and people parroting the blanket answers. The reality for me is that it can depend on the application...and especially if it's a 4 cylinder. I've owned nothing but four cylinder cars for the last 38 years and I can tell you that depending on the oil and the car, there can be a repeatable ( albeit small ) difference in MPG that's outside the realm of statistical noise.

I've had two or more cars where switching to synthetic motor and gear oil gave me an FE increase in the 3% range. ~ 1 MPG

Sometimes, it seems statistical noise is stretched to 5% on here and if inputs are then controlled to go back to losing that 5% then that's noise too with stop light, traffic, average speed, tire pressure, and intestinal gas creating the delta on both ends. My take is that you can potentially be getting 1-2 more MPG in the right circumstance but it probably wouldn't be acknowledged here.
 
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