Gas increase with Castrol High Mileage

[MolaKule]

Here are some theories:

1. slightly increased viscosity of HM sealed rings better resulting in higher compression and more useful work from each cyclinder,

2. HM may have contained a bit more friction reducer than other oils you have used.

 

[Hadrien]

I just recently bought my girlfriend a little 92 Mazda MX3. It had 107K on it when she got it, and it had just had an oil change with 10W30 Pennzoil (according to the oil change sticker).

I let her run that for about 1500 miles due to the fact I was working 12 hour days 7 days a week. During those 1500 miles she usually got about 26-27MPG, which wasnt awful for mixed driving.

I did an oil change on it in Feburary with 10W30 Castrol High Mileage and a PureOne filter. She was getting about 27-28MPG at first, but recently she has been getting 28-29MPG and the other night she got 31MPG when she filled up and crunched the numbers. I have her keep a log to see how the mileage is doing.

I contribute the better mileage mostly due to the fact that it is no longer winter and she isnt blasting the heat the entire time she is in the car. But maybe, just maybe the oil did help a little.

On a side note. Her car only holds a little under 4 quarts. I usually get the 1 gallon jugs of Castrol High Mileage (since its more cost effective) from WalMart and leave it in the back of her car incase she ever needs to top it off.

Is it safe to use the rest of the 1 gallon jug the next oil change since it sits in the car with the changing temperature? Or should I just get another new jug and keep the remainder inside after the oil change since I know I wont use it all. Thanks in advance.

 

[grbr95]

Is it safe to keep the oil in your crank case with the change of temperatures, or should everyone change their oil everytime the temperature changes?

hehehehe

 

[UncleS2]

Yes, the leftover oil's safe to use. Don't worry about it.

 

[ConfederateTyrant]

I'm leaning towards your theories MolaKule, I was also thinking that winter fuel caused the decrease with GTX, but the increase was instant, not gradual. I never did any straight highway with GTX, but I would average together my 420 mile round trips with the High Mileage and they were between 26-27 mpg highway. Only used High Mileage during warmer months, March through November. Highway trips only took place with High Mileage oil in August, September, and October, which for Georgia was pretty warm, so I doubt the winter gas was in full use.

I installed Amsoil 5w30 and it averaged 25.5 mpg highway at the same speeds, but this was during December and January, so winter gas blend could explain that, plus the temperatures were finally getting into the freezing and below freezing area.

Hadrien, I've heard a few people say that they've gotten the same results from just using High Mileage. And to answer your question, the oil should be safe. How long do you go between changes, 3 months, 6 months, 1 year? I'd say that if you went a year then it may not be safe, but 3-6 months should not be enough time to degrade the oil.

 

[MarkC]

"I contribute the better mileage mostly due to the fact that it is no longer winter and she isnt blasting the heat the entire time she is in the car."
How would running the heater affect the gas mileage?
Just circulate warm coolant through the heater core and run the fan....

 

[ConfederateTyrant]

I'm not a big fan of my heater, so I doubt it caused a decrease in my car. I don't think it uses as much power as the AC system. On my car the heat is nothing more than the vent with the heat adjusted to the red, I don't have a heater option on my controls. Doesn't seem to take as much effort as running the AC system.

 

[Cutehumor]

quote:

---

Originally posted by grbr95:
Is it safe to keep the oil in your crank case with the change of temperatures, or should everyone change their oil everytime the temperature changes?

hehehehe

---

don't you change your oil every 3 mo when the season changes?

 

[Hadrien]

quote:

---

Originally posted by grbr95:
Is it safe to keep the oil in your crank case with the change of temperatures, or should everyone change their oil everytime the temperature changes?

hehehehe

---

True true true. My automotive logic engine (Im a software/hardware geek) isnt quite up to snuff yet. I was just uncertain if the temperature change would allow more condensation or water to get into an unsealed bottle of oil and contaminate it permanately. I plan on changing the oil in her car every 3000-3500 miles.

I will say this. Her car seems to accelerate smoother even to this day with the Castrol HM in it than it did with the Pennzoil. Its a little bit more expensive but not terribly.

 

[Mr Magoo]

For those who want a very cheap HM oil.

Advance Auto Parts has Havoline HM for 49 cents (clearance sale)

I bought 20 quarts this week. Just thought I would pass this info also, cause alot of people on BITOG like HM oils.

 

[BrianWC]

Hah, mine put it on clearance but for $1.95! What a clearance!

 

[Hadrien]

quote:

---

Originally posted by Mr Magoo:

For those who want a very cheap HM oil.

Advance Auto Parts has Havoline HM for 49 cents (clearance sale)

I bought 20 quarts this week. Just thought I would pass this info also, cause alot of people on BITOG like HM oils.

---

I just wonder if all High Mileage oils are somewhat equal, or if they are 90% snake oil and 10% motor oil.

 

[Hirev]

How many miles on your car? I own a 91 Toyota pickup I bought new so I've checked mileage a lot over the years. As the miles got up there I stated using 15w 40 HDEO in the Summer the last 4 years. It it interesting to note the best mileage I've consistently recorded over the years has been with Mobil 1300 and Chevron Delo 400 15w 40.

They seems to make about 1.5 MPG increase over XX - 30 in this truck. I think ring seal may be a factor in my case. Two years ago I changed back to 5w 30 at the end of August before winter fuels came out and instantly lost 1.5 MPG.

 

[GROUCHO MARX]

"For those who want a very cheap HM oil."
---------------------------------------------------------

Max-Life FAR

 

[ConfederateTyrant]

My car has 105,000 miles now, but I used Castrol High Mileage from 92,000-97,000 miles.

Ring seal could definitely be a factor, just proof that higher viscosity doesn't lead to decreased gas mileage. The Amsoil 5w30 thickened up in my car to a low 40 weight, and no drop in gas mileage.

 

[jeepman]

I have used the WW SuperTech High Mileage 10W30 before and thought it was just as good as anything. At $6.68 for a 5 qt jug it's pretty hard to beat the price. With that said, I just put another post out there that I just started using Havoline dino this week, and am darn impressed with the quality of that oil. So I would cast my vote for the Havoline HM if you don't mind spending a couple of bucks more, although the Supertech HM with a Supertech filter gives you a complete oil change for around $9.00, which is hard to beat...

 

[Mr Magoo]

LOL,

I also mailed in my Maxlife Free After Rebate offer last week. But that Maxlife offer is only good for 5 quarts.

49 cent Havoline HM & Havoline Syn Blend is hard to pass up considering how much other HM oils go for.

 

[GoldenRod]

Confed: Did you notice any difference in mileage between HM 5w30 and HM 10w30?

 

[ConfederateTyrant]

I no longer use Castrol since I have switched to Amsoil, but I was wondering if someone could shed some light on this. Two years ago when I was in high school, I was using Castrol GTX 10w30 and my city fuel economy was always coming about to be in the mid 16 mpg area, usually around 16.5 mpg. Someone recommended using the High Mileage oil, so I gave it a shot and I used the 10w30 for 6 months, then 5w30 for another 3 months, and each time I filled up, my city mileage was in the low 18 mpg, usually around 18.2 mpg in the city. I didn't change my driving habits, and I still drove the same routes to school, grandmother's, work, home, and girlfriend's house.

From what I have read on here is that the High Mileage oils are thicker so wouldn't it be more logical to have a drop in gas mileage? Are there any other additives that lead to that much (about 1.5 mpg) increase?

[ April 06, 2006, 12:38 PM: Message edited by: ConfederateTyrant ]

 

[TR3-2001SE]

What may have happen to you is an increase in tire pressure. It can make a lot of difference in mpg as is the single most increase you will ever notice. My Honda Accord went from 25-26 around town to 27-28 around town with an added 7psi. Oil probably made no difference at all.