i've been using mobile 1 full synthetic engine oil ever since i got my car a yr ago. mileage has been quite promising, 28-32 hwy..or somewhere around that number. however, recently i've changed it to castrol due to the whole region of where i live was out of mobile 1 5w-20 full synth....so i had no choice but get the second largest brand in the world(or third), full synth. after i changed it, drove the same distance as i do everyday...but the number had dropped. i had to fill up at 27 when i hit mostly high ways, and once in awhile, i'll get 29 with all high ways..and i was not doing heel/toe or hard rev or any other practices that causes mileage decreased.

so my question is: does diff. brand of engine oil effects the mileage of the FIT? by far, Mobile 1 is doing fine, i got Castrol now, and i saw the diff...what do you guys/girls think?

 

The viscosity of the oil you use should play a bigger role than the brand. My two cents

 

Some folks switch to 0w-20 oil for economy...

 

how is 0w-20 to regular 5-20? lot thinner? so, regardless of brand, but both are 5w-20, how would one kind made an effect on mileage than the previous one?

 

i think 0w-20 is just thinner when it's cold, but the same as 5w-20 when it's warm.

the W stands for winter.

 

sorry no offense but, my question still hasnt been answered yet...how could both kind of engine oil, same grade, one could effect the mileage and the other one didnt?!

 

If the viscosity did not change between brands, then there is no reason for the MPG drop. The drop must be from something else. Outside temp drop, change in driving patterns, etc.

Also, unless Mobil-1 and Castrol changed their formulation, neither are "Full Synthetic", but rather Group III hydrocracked mineral oil.

I wanted to clarify this a bit. It goes against logic that oil gets thinner as it gets colder and thicker as it gets warmer. Both 0w-20 and 5w-20 gets thicker as the temps drop. The difference is in the additive package which allows the 0w-20 to have a better cold flow rating than the 5w-20

Interstate526 is correct that "W" stands for winter. 0w,5w,10w, is nothing more than a cold flow rating and not a "weight" as many believe.

 

its your foot. change the way you drive

 

thanks for clearin' that up, i do think they changed their way making the oil...anyother opinions?

 

^ fyi, i've been driving the same as i first got the car, i dont do heel/toe motion or hard rev anymore as i stated in my first post! i used to when i had my dc5, but not this, i got a kid in the back, so i drive as gently as i could all the time.

 

it isnt about driving gentle, driving like a grandma, or any of that. driving fuel efficiently takes a lot of time and technique

 

The thinner synthetic gets better mpg because its easier to pump at 30 to 70 psi. 0-20W is thinner at low temps than 5W-20.start up but same viscosity at running temp. Your fit runs considerable time at lower temps so then you consume more gas with 5w than with 0W.
PS oil production hasn't really changed in 40 years but the additives may be different. Its one of those additives that causesthe oil viscosity to reduce at low temps instead of thickening. Their known as VI's - viscosity modifiers.

 

It depends how you drive, my last few tanks have been between 34.0 and 34.9 mpg both city and hwy driving with sport auto running regular 5w-20 oil...

 

I remember reading that 0w-20 oil does not prolong longevity of the motor as 5w-20 oil does. Can someone vouch for this statement? the recommended oil for the car is 5w-do so would it do any harm running the 0w-20 to increase fuel efficiency? and are there any negatives to driving hard running 0w-20.

 

It depends on the clearances in the engine. Yes, thinner oil is not as good a long term lube as thicker but then the tighter the clearances the less easy it is for oil to lube. Our 2004 Civic HX stillruns on 5W-20 oil with no lost and still gets 40-44 mpg at 120,000 miles.
When you see NASCAR running very light opil for qualifying they will change it before the race. And theur clearances are a trifle greater than a Fit's.
The great thing about synthetics is their ability to withstand spreading out in thin sheets without 'tearing'.The weight oil is not the prime factor, just the ability to be spread out in thin sheets (as in a bearing) without tearing to expose metal-to-metal contact. Few normal hydrocarbon oils, (if any) can excel at that.

 

it IS about driving gently/grandma AND using "techniques"

grandmas accelerate slowly and have lower top speeds - i'd like to hear your justifications on that

as for gentle...gentle acceleration only

u can drive "hard" like not slowing down 4 corners, tailgating ahem i mean drafting, not stopping for stop signs/red lights to gain fuel economy but your grandma comment......?

 

thanks. yeah, I wasn't trying to say that it's thinner at colder temps, but the 0w will flow better at colder temps than a 5w.

 

its more than just driving slow. its driving smart. THROTTLE POSITION>RPM

 

oil brand won't make a difference. just like solbrothers said. its your foot

 

reeeeeeeeeeeeeeeeeeeeeeeeeeeeeeepped!