T
Tony Hwang
Hi,BG said:
As far as I know mixing two different oil brand, weight is considerd
not a good idea. If I were you, I wouldn't do that.
Tony
As far as I know mixing two different oil brand, weight is considerd
not a good idea. If I were you, I wouldn't do that.
Tony
B
Byron
Tony said:
As long as both kinds of oil meet or beat Subaru's requirement of
viscosity and API specification for spark-ignition engines I'm pretty
sure you'll be just fine. My owners manual specifically says I could
use different brands simultaneously, as long as they meet the specs.
My '02 WRX requires SH or newer - check your owners manual for your
Outback if you want more piece of mind. Mine prefers 5w-30 for general
use, but allows the use of 10w30 and 10w40. It also says that under
severe duty, SAE30, SAE40, 10w50, 20w40, or 20w50 can be used to suit
the load and expected temperatures.
The latest designation is SL. If the car requires SH, you can use any
combination of SH(1994), SJ(1998), or SL(2001?) oils. You just couldn't
use an oil that only met an older designation like SG(1987)
I've always used the recommended oil. I moved from Boston, MA to
Phoenix, AZ nearly a month ago (it's 110F today) and am switching from
fossil oil to Mobil1, still in the 5w30 weight.
- Byron
D
Don
Tony said:
If I can trust my dealer he said NOT to use anything heavier than
10W30 because you don't get the proper lubrication. I.e., switching
to 90W gear lube certainly wouldn't improve things, eh? ;-)
Username munged by FixNews
H
Henry Paul
Wow that is interesting since the difference between 10w30 and 10w40 is
small in terms of viscosity.
What car do you have? My Impreza manual says I can run 20w50 if I want, but
5w30 will yield best fuel economy.
small in terms of viscosity.
What car do you have? My Impreza manual says I can run 20w50 if I want, but
5w30 will yield best fuel economy.
D
Don
Wouldn't the difference between 10W30 and 10W40 be 25% difference?
That's quite a bit. And for the worst temperature condition.
The higher number represents the viscosity at cold temperatures
when the engine need lubrication to help prevent piston slap, etc.
Don't believe me, check http://www.ixion.org.uk/faq/oil.html
That's quite a bit. And for the worst temperature condition.
The higher number represents the viscosity at cold temperatures
when the engine need lubrication to help prevent piston slap, etc.
Don't believe me, check http://www.ixion.org.uk/faq/oil.html
Username munged by FixNewsHenry said:
H
Henry Paul
I ran 20w50 all the time when I lived in Oregon because of the moderate
climate. It's too cold here in the winter to run that thick. Engine won't
even turn over without a block heater.
It does get pretty hot here in the summer so I run a thicker oil then
because it will stay thicker under higher temps.
climate. It's too cold here in the winter to run that thick. Engine won't
even turn over without a block heater.
It does get pretty hot here in the summer so I run a thicker oil then
because it will stay thicker under higher temps.
T
Tony Hwang
Hi,Byron said:
I think you're misinformed. No mixing! period.
Tony
B
Byron
Hi,
You might want to tell the engineers at Subaru that they are also wrong,
because my info came right from my owners manual (page 11-13). A
mechanic I know who has built hundreds of high performance engines also
agrees with them and me - meet or beat the API service rating, and keep
the viscosity rating at one of Subaru's recommended levels for the load
and temperature range your car will see.
Mobil1 oil also states that it can be freely mixed in any proportions
with conventional oil.
Where does your information come from? Can you post a link? Or explain
why you think Subaru is wrong?
You might want to tell the engineers at Subaru that they are also wrong,
because my info came right from my owners manual (page 11-13). A
mechanic I know who has built hundreds of high performance engines also
agrees with them and me - meet or beat the API service rating, and keep
the viscosity rating at one of Subaru's recommended levels for the load
and temperature range your car will see.
Mobil1 oil also states that it can be freely mixed in any proportions
with conventional oil.
Where does your information come from? Can you post a link? Or explain
why you think Subaru is wrong?
B
BoB
Hi Byron,
I'm moving from TN to Phoenix in two weeks and am curious if
dealers there recommend a particular weight for that hot climate.
I was going to change oil in my ForesterS this week but decided
to wait and introduce myself to a Phoenix dealer, since I will
be trailer towing the Forester behind the rental truck. I only
find one Phoenix dealer on My.Subaru.com, but they may have to
'special qualify' or 'pay' to get a listing. My dealer here isn't
listed either but one 30 miles down the freeway is.
We'll be house shopping in Sun City West if we survive packing
and loading.
BoB
Y
y_p_w
Byron said:
I remember an NG thread about mixing oils. Someone with excellent
credentials (oil/fuel additive developer and engine lab director
at Exxon) claimed that some detergent additives mixed together
could cause (maybe a 50/50 mix) of two different 5W-30 oils to
thicken out to a 15W-40. I don't think this is that big a deal
if you're changing oil.
I think now there's probably far more similarities than differences
in additive packages these days.
Y
y_p_w
Don said:
Not really. The number 30/40/50/etc represents a range of viscosity
that meets the requirement. A 10W-30 oil could be right at the upper
limit of just under 12.5 cSt at 100°C. A 10W-40 could be right at
the lower limit of 12.5. These probably aren't typical.
<http://www.finalube.com/reference_material/SAE_Viscosity_Grades_For_Engine_Oils.htm>
These are the viscosities (in cSt at 100°C) for Chevron Supreme motor
oil (from their datasheet):
5W-20: 8.0
5W-30: 10.8
10W-30: 10.8
10W-40: 14.8
20W-50: 19.0
30 wt: 10.3
40 wt: 14.0
I also found it interesting that their 30 wt oil is thinner at 40°C
(104°F) than their 10W-40 or 20W-50. If you're running it in a
desert climate, it sounds like 30 wt could be a better choice than
10W-30 for cold engine starts.
Besides that - I don't think that viscosity can really be quantified
as X% thicker. It's just a number that might not be linear with
different scales.
But it's only a range. Not all 10W-30 motor oils are of the
same thickness.
H
Henry Paul
So then if you use 2 different weights from the same brand it should work
just fine.
just fine.
H
Henry Paul
But also take into consideration that a "cold start" in a hot climate is at
a warmer temp than a cold start in a moderate or colder climate.
a warmer temp than a cold start in a moderate or colder climate.
Y
y_p_w
Henry said:
Yes. I only used that example because the datasheets I had listed
viscosity at 40°C (a hot climate) and 100°C (near operating temps). I
still found it odd that 30 wt oil would be thinner at 40°C than their
10W-30.
I also have the feeling that what's currently called a "straight weight"
oil might have been considered a multiweight oil in the past. The
manufacturing process for motor oil is likely far different than even
a decade ago.
Y
y_p_w
Henry said:
Perhaps. I once called the Mobil 800 number and asked if it was OK
to mix equal part of Mobil 1 0W-30 and 5W-30. It was what I had on
hand, and the answer was yes.
However, motor oil makers modify their base oil and additive packages
all the time. Castrol states just that on their label. I've seen the
same brand/weight with noticeable color/odor differences; I bought them
at the same time. I couldn't imagine a radical change in additive
package that would lead to thickening though. I'd think an oil maker
would test for compatibility with their previous formulations.
I found the original post I referred to:
<http://groups.google.com/[email protected]&output=gplain>
H
Henry Paul
That's true. My dad keeps telling me those stories, "I remember when there
was only one type of oil you could buy back before all the multiweights were
available......."
My dad was stationed in the army in Alaska and he also told me stories about
motor oil in the winter time up there.
was only one type of oil you could buy back before all the multiweights were
available......."
My dad was stationed in the army in Alaska and he also told me stories about
motor oil in the winter time up there.
D
DCM
The number 30/40/50/etc represents a range of viscosity
Don't know if this moves the thread forward, but here goes.
Viscosity is a measurement of what we generally conceive as the
thickness of a fluid. Pudding has a much higher viscosity than beer.
Jello is a pretty normal fluid when we're taling about viscosity.
When the Jello is just made, it's hot and thin. After time in the
'fridge, it gets rubbery thick.
Liquid viscosities change because they are affected by temperature and
pressure. The molecules have more or less energy and pack less or more
tightly as the temperature goes up. .... That's in liquids which obey
the rules of Thermodynamics Newton put together in the 18th century.
NON-Newtonian fluids DON'T FOLLOW THE RULES (those pesky creatures).
They keep the same viscosities at different temperatures and pressures.
Ball point pen ink is an example of a pressure-dependent non-Newtonian
liquid. In the pen, it's REALLY thick. At the moment of shear, under
the pressure of passing over the ball and onto the paper, it's viscosity
collapses and it flows onto the paper where it reqains its earlier
thickness and doesn't run all over everything.
Modern motor lubricating oil is made to keep the same thickness despite
dramatic changes in temperature AND pressure. Since the Society of
Automotive Engineers is loath to change anything they've been using for
awhile (consider the metric system of measurement) they created a way of
defining motor oil viscosity which encompassed the modern
keep-the-same-thickness-across-a-temperature-range "multi-viscosity oil"
10W-40 or 5W-30 really means the viscosity STAYS THE SAME at different
temperatures and pressures. You can still find 30W and 40W oils in some
stores. People used to say,"Thirty weight oil" or "Forty weight oil"
when refering to these fixed viscosity lubricants.
If you expect to operate your vehicle in high temperatures all the time,
a heavier range of oil will protect the engine as it first starts
running, but not break down in the heat. If you're heading to the polar
cold, thinner oil won't turn to jelly when it's cold, but still protect
the engine when it's at operating temps. You still need the lubricating
capability, so the ranged viscosity keeps the engine protected across
the temperature and pressure ranges.
Don't know if this moves the thread forward, but here goes.
Viscosity is a measurement of what we generally conceive as the
thickness of a fluid. Pudding has a much higher viscosity than beer.
Jello is a pretty normal fluid when we're taling about viscosity.
When the Jello is just made, it's hot and thin. After time in the
'fridge, it gets rubbery thick.
Liquid viscosities change because they are affected by temperature and
pressure. The molecules have more or less energy and pack less or more
tightly as the temperature goes up. .... That's in liquids which obey
the rules of Thermodynamics Newton put together in the 18th century.
NON-Newtonian fluids DON'T FOLLOW THE RULES (those pesky creatures).
They keep the same viscosities at different temperatures and pressures.
Ball point pen ink is an example of a pressure-dependent non-Newtonian
liquid. In the pen, it's REALLY thick. At the moment of shear, under
the pressure of passing over the ball and onto the paper, it's viscosity
collapses and it flows onto the paper where it reqains its earlier
thickness and doesn't run all over everything.
Modern motor lubricating oil is made to keep the same thickness despite
dramatic changes in temperature AND pressure. Since the Society of
Automotive Engineers is loath to change anything they've been using for
awhile (consider the metric system of measurement) they created a way of
defining motor oil viscosity which encompassed the modern
keep-the-same-thickness-across-a-temperature-range "multi-viscosity oil"
10W-40 or 5W-30 really means the viscosity STAYS THE SAME at different
temperatures and pressures. You can still find 30W and 40W oils in some
stores. People used to say,"Thirty weight oil" or "Forty weight oil"
when refering to these fixed viscosity lubricants.
If you expect to operate your vehicle in high temperatures all the time,
a heavier range of oil will protect the engine as it first starts
running, but not break down in the heat. If you're heading to the polar
cold, thinner oil won't turn to jelly when it's cold, but still protect
the engine when it's at operating temps. You still need the lubricating
capability, so the ranged viscosity keeps the engine protected across
the temperature and pressure ranges.
H
Henry Paul
We have an extreme range of temperatures where I live. I change my own oil
and I notice substantial differences in the viscosity of the oil both out of
the jug and out of the engine when I change it based on the temperature
outside. It pours easier when it's hot and not as easy when it is cold. If
it is cold enough, it pours even slower.
and I notice substantial differences in the viscosity of the oil both out of
the jug and out of the engine when I change it based on the temperature
outside. It pours easier when it's hot and not as easy when it is cold. If
it is cold enough, it pours even slower.
P
Philip Procter
That's backwards:
When cold, 10w40 acts like a 10w
When hot, 10w40 acts like a 40w
The question I have is protection from start-up wear and in the high
speed bearings of a turbocharger?
One of the big oil companies (Castrol, I think) is making a big deal
about its special polymers thant stay on the metal and lube it during
those crucial first seconds after sstartup. Anyone know how much is
truth and how much is marketing?
Also, the high speeds and extreme temperatures in a turbo would seem
to demand a unique oil formulation. Anyone know if any of today oils
or synthetics are better for turbos than others?
Thanks,
Philip
When cold, 10w40 acts like a 10w
When hot, 10w40 acts like a 40w
The question I have is protection from start-up wear and in the high
speed bearings of a turbocharger?
One of the big oil companies (Castrol, I think) is making a big deal
about its special polymers thant stay on the metal and lube it during
those crucial first seconds after sstartup. Anyone know how much is
truth and how much is marketing?
Also, the high speeds and extreme temperatures in a turbo would seem
to demand a unique oil formulation. Anyone know if any of today oils
or synthetics are better for turbos than others?
Thanks,
Philip
J
Juhan Leemet
I remember (decades ago) people in the Montreal Alfa club liked the oil
additive "MolySlip" (with molybdenum disulphide ISTR?) This worked sort of
like a suspended high temperature graphite grease: slippery "plates" of
molecules, which would settle on bearing surfaces and supposedly provided
lubrication when there wasn't much oil in the journals. I remember using
it in my 2000 GTV a couple of times, too. One of the track racers claimed
it saved his engine once when he put a hole in the oil pan and didn't
notice (until the smoke?). OTOH, others warn against additives that might
gum up the works. Dunno. Anybody use anything like MolySlip these days?