Gas mileage improvements?

[cruiser54]

I found my wife's 88 XJ dropped from 16.5 around town at 5000 ft elevation to 13 over the last two tanks.
I hooked up my DRB-11 suspecting a faulty CTS. I found that the CTS was tellling the ECM that my engine temp was 167*. So I started shooting spots on the engine like the thermostat housing and found that in fact it was running about 172*. I replaced the 8 month old faulty Napa premium stat with a new one and she drove it for a week. Filled up last night. Over 17 MPG now.

 

[kastein]

I just completed a 336 mile (541km) road trip this weekend. Average speed was 60-65mph and most of it was in 5th gear. I filled the fuel tank to the brim and zeroed the trip meter before I set off. After I returned I refilled the tank and it took 15.9 US gallons (60.2 liters) yielding an average of 21mpg or 11.1L/100km. I was pretty impressed.
I normally get 16mpg (~14.5L/100km) city and 19mpg (~12.5L/100km) highway (75-80mph cruise).

This is EXACTLY how any post claiming mileage (especially high or low mileage) should be written.

 

[kidarkitect]

Something I just realized, that most of you would probably say duh to, is that recently noticed I haven't been getting as good of gas mileage- and the problem was I switched oil to High Mileage which is way thicker and not an "energy stamped" oil. I should have realized it considering how long I was Jiffy Lube Grease Monkey.

Also, I am under the belief that my front skid helps for highway mileage, its probably only a small amount but it is helping create less wind-drag on the all them parts underneath.

Does anyone think installing locking hubs might help if you have a non-disco axle. It seems it would cut down on a bit of resistance.

 

[keep0njeepin0n]

Something I just realized, that most of you would probably say duh to, is that recently noticed I haven't been getting as good of gas mileage- and the problem was I switched oil to High Mileage which is way thicker and not an "energy stamped" oil. I should have realized it considering how long I was Jiffy Lube Grease Monkey.

Also, I am under the belief that my front skid helps for highway mileage, its probably only a small amount but it is helping create less wind-drag on the all them parts underneath.

Does anyone think installing locking hubs might help if you have a non-disco axle. It seems it would cut down on a bit of resistance.

"High Mileage" oil has nothing to due with thickness. If you stayed with 10w30, the thickness is the same weather it's high mileage or regular.

 

[ert01]

I just installed my Precision Auto 1 hole injectors in my 98 XJ and it LOVES them! I can't comment on mileage just yet, I'll know better after a couple tanks, but idle is much smoother, better throttle response and definately more power right now.

 

[Johnnie Walker]

Earlier in the thread somebody said you have to change the oil after you fun sea-foam through. Should I run my sea-foam through before I change my oil? It's in need of an oil change soon... So is it better to wait?

That is worded horribly but I think it gets my point across. :gee:

You CAN run it in your oil, but it is solvent-based, which means it can break down your pil. Some swear by it and use it that way.
For me, and soem others. I would recommed Put it in your crankcase anywhere from 500miles- to 20-30 min run time before you change your oil.
You can run it in your intake and/or gas tank at any time.

 

[kidarkitect]

wanna bet? thats the story sure, but according to the quacker state/pennzoil rep the oils are made to the max cutoff point before it would be classified as the next level.

So 10w30 HM is more like a 14w39. It is part of how the oil "conditions" your seals along with the other additive.

dont take my word for it though:

http://www.quakerstate.com/#/motor-oil/higher-mileage-engine

check out where it says "Protect worn engine parts with a thicker oil blend"

 

[keep0njeepin0n]

wanna bet? thats the story sure, but according to the quacker state/pennzoil rep the oils are made to the max cutoff point before it would be classified as the next level.

So 10w30 HM is more like a 14w39. It is part of how the oil "conditions" your seals along with the other additive.

dont take my word for it though:

http://www.quakerstate.com/#/motor-oil/higher-mileage-engine

check out where it says "Protect worn engine parts with a thicker oil blend"

Use a better oil...I wouldn't run Quaker state or penzoil in anything I owned short of a lawn mower, even then I would only do it if that's all they had in stock.

I would switch to something like Valvoline Max Life...it's also a synthetic blend and not too pricy!!

http://valvoline.com/products/consumer-products/motor-oil/higher-mileage-motor-oil/2

With their logic, and if you're dead set on using their products, then use their 5w20 himi oil. That should get you closer to an actual 10w30 conventional oil.

 

[kidarkitect]

same thing with valvoline.
hears a links showing their viscosities:

valv conventional
http://www.valvoline.com/pdf/All-Climate.pdf
valv maxlife
http://www.valvoline.com/pdf/Maxlife.pdf

i can show you the same for mobil as well. I'm NOT saying there aren't additives but they are all the thickest you can get and still be in that class. which will cause parasitic loss, how much depends on too many variables so your results may vary some. mine were significant.

 

[bigalpha]

I got a Saturn for my mileage increase

I actually got shoddy mileage in my XJ. My MJ doesn't get much better but it's not in the best of shape.

 

[kastein]

I got a Saturn for my mileage increase

to be fair you have to deduct oil consumption from your fuel mileage :lecture:

 

[keep0njeepin0n]

Something I just realized, that most of you would probably say duh to, is that recently noticed I haven't been getting as good of gas mileage- and the problem was I switched oil to High Mileage which is way thicker and not an "energy stamped" oil. I should have realized it considering how long I was Jiffy Lube Grease Monkey.

same thing with valvoline.
hears a links showing their viscosities:

valv conventional
http://www.valvoline.com/pdf/All-Climate.pdf
valv maxlife
http://www.valvoline.com/pdf/Maxlife.pdf

i can show you the same for mobil as well. I'm NOT saying there aren't additives but they are all the thickest you can get and still be in that class. which will cause parasitic loss, how much depends on too many variables so your results may vary some. mine were significant.

Ok so I take my words back, it appears as though the "thickness" or viscosity does slightly increase with the himi oils. Enough to create a NOTICEABLE decrease in fuel economy??? VERY doubtful! You said before that the himi oil was "way thicker", which according to valvoline, their max life is only 0.72 points higher, or thicker on the viscosity index than their conventional for hot temps and 5.26 points higher in cold temps. You will never convince me, or anybody else with any knowledge of internal combustion engines that those numbers are "significant" enough to cause a loss so drastic as for you to notice it in 20 gallons of fuel usage. There's just NO WAY!!!

 

[kidarkitect]

to be fair you have to deduct oil consumption from your fuel mileage :lecture:

hahahaha


keepon:I guess i should have clarified I was switching from conventional 5 w30 to 10w30hm and back. Its definitely not as noticeable in summer but in winter most of my trips are less than 5 miles in
30deg F (-1 celcius) which is probably why i notice it. i have idiot gauges currently so i cant tell you what operating temp is in that time but its not enough to to keep me warm from the heat vents most of the time.

oh and all oil brands are all the same :gag:

 

[kidarkitect]

oh and i was just quoting the numbers that the rep told me. so that was my bad.

 

[bigalpha]

to be fair you have to deduct oil consumption from your fuel mileage :lecture:

True, but at 30mpg+ a couple of quarts of oil isn't asking too much.

 

[kidarkitect]

yeah saturns can be a good gas sipper. I think they got a bad rap because most of the masses who buy american cars either don't care to or cant afford to maintain them properly.

I've seen some that were taken good care of, regarding basic maintenance and they went for a longs time.

I've seen a lot that came to my work that were 5000miles over, they'd never checked the oil in the meantime, two quarts + low. and low and behold after a bit they start having valves knocking or other engine problems.

Does anyone know if locking hubs would help??? I am really curious, got a vac disco in mine atm but looking at a swap to non disco.

 

[CherBear]

Do you think installing a TC lock up switch could help with highway mpg? IIRC the AW4 handles all of that automatically like most auto transmissions... worth a try?

 

[kastein]

it does handle it automatically... generally when it unlocks, it is for a good reason, like you trying to accelerate and wanting a bit more torque.

 

[bigalpha]

I would think that locking hubs would work somewhat since you wouldn't be spinning any of the attached drive train when it was unlocked.

I seem to recall some people having used the locking hubs and not noticing any appreciable increase in their mileage.

 

[CherBear]

I would think that locking hubs would work somewhat since you wouldn't be spinning any of the attached drive train when it was unlocked.

I seem to recall some people having used the locking hubs and not noticing any appreciable increase in their mileage.

Well it should help, not going to do armchair engineering, but anytime you reduce friction, you increase efficiency. Probably a very small amount, hubs arent that difficult to turn as compared to all the work being done just to move the car.