'Summer weight oil'

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336
Location
White House, TN USA
I see a lot of references in here to people running a different 'hot weight' oil in the summer vs the winter. Now I can understand that you would want different 'cold weight' numbers depending on ambient temperatures, so I can see using a 10W30 in the summer and a 0W30 in the winter in Chicago, for example. What I can't see is any effect of ambient temperature on the oil temperature when the engine is fully warm! My current vehicle runs a steady 210 degrees when hot, summer or winter. I suspect almost all modern vehicles do (except for air-cooled). What would possibly be the justification for running 30 weight at one time and 40 weight at another, AT THE SAME ENGINE TEMPERATURE? [I dont know]
 
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2,556
Location
Columbus Ohio
Coolant temperature, is not the same as oil temp. If you are referring to an actual oil temp guage........and it never moves, no matter what ambient temp is, or no matter the driving conditions..........then the guage is bad.
 
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23,591
Scenario 1: ambient temp 75 degr freeway cruising at 2800 RPM oil temp 212 degr Scenario 2: ambient temp 75 degr freeway racing at 6500 RPM oil temp 230 degr F Scenario 3: ambient temp 100 degr F freeway crusing at 2900 RPM oil temp 220 degr F Scenario 4: ambient temp 100 degr F stuck in traffic at idle, A/C running, breathing exhaust from other cars oil temp 250 degr F Believe me, if your oil gets hotter than 230 degree F, you wish you had that extra protection the thicker oil can provide. [ February 24, 2004, 06:34 PM: Message edited by: moribundman ]
 
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575
Location
Wisconsin
I had an oil temp gauge on a race car that I used to street drive to the events. On hot days (85+) the oil temperature would reach up to 220 degrees with a steady 190 on the highway. On Cool days (50-60) it would stay pegged at the bottom of the gauge and not move off the needle on the highway and 170 tops. No oil cooler and coolant would always be the same temp unless I changed the settings on my electric fan.
 
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4,872
Location
MN
Good point guys, I've always thought like the original poster. However, what if your car has an oil cooler? -T
 
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700
Location
USA
If you use a 15-40 or 40w oil in a car designed for 30w, you will have more resistance with the heavier oil and it get the 40w oil hotter (and thinner) than the 30w.
 
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23,591
Hmm, I wonder what viscosity my Audi engine was desgined for. According to the manual, I can use anyting from 0W-30 to 20W-50. [Wink] Does anybody seriously believe that at high oil temps (230 degr F and up) the lower viscosity will cause so much more internal friction that it will contribute rather to overheating than protection? I know I'm not inclined to use the thinnest allowed oil during the summer. Just call it dumb horse sense.
 
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1,565
Location
palm beach
car oil temps dont run at a constant 100c unless you have a thermostatic oil control valve (rare). so if you are running your 10w30 at 130c you might be infact running a 20 weight because the oil is hotter than the 100c testing tempature for a 30 weight. likewise, that 10w30 at 70c might be a 40 or 50 weight. so lets say for example youre car specs a 30 weight oil @ 100c oil temp, you are doing some hard running and heating the oil up to 130c, this 30 weight oil at this temp may infact be a 20 weight, as oil thins at it heats up. therefore, in order to keep the oil a 30 weight you may need to run a 40 weight. another example, youre driving along in the middle of winter with the same engine speced for a 30 weight at 100c oil temp. youre oil temp is 70c, now with a 30 weight, this may be infact a 40 or 50 weight, as it is not at 100c, so you may need to run a 20 weight oil in order to get a 30 weight at 70c. cooler oil is thicker, and hotter oil is thinner. you may need to alter the "warm" oil number to suit your driving conditions. an easier alternative is to install an oil cooler with a thermostatic valve, which basically blocks off the oil cooler untill it is needed. like a thermostat in a water cooling system. this way youre oil temp will awalys be the same (assuming your oil cooler is up to suff) so you can run the same oil year round and not worry about tempature variations. this is why people who race somtimes use thicker oils, when they are running around the track, that 20w50 billy bob installed in his camaro aint' no 50 no mo'.
 

Patman

Staff member
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22,005
Location
Guelph, Ontario
quote:
Originally posted by Dick in Falls Church: IMO, if you are using a good synthetic, summer vs winter oil is akin to summer air vs winter air in your tires!
I agree, I got great results in the heat of summer with 0w30 GC, even though most people might've considered that a winter only type of oil (those outside of this forum that is)
 
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13,132
Location
By Detroit
quote:
Originally posted by JonS: If you use a 15-40 or 40w oil in a car designed for 30w, you will have more resistance with the heavier oil and it get the 40w oil hotter (and thinner) than the 30w.
Maybe, but who knows what oil an engine was designed for. Now for a slightly unfair example to the contrary: My Ford 300 I6 apparently was designed for a range of grades (older truck's owner manuals) but in '95 it says 10w30 with 5w30 optional under 60 F. However, I am running 10w40. Is my 10w40 going thinner than the 5w30 I was running? No. My Autometer mechanical oil pressure gauge was reading 36 psi hot at 2000 with the 5w30 and is reading 45 psi hot at 2000 with the 10w40. The conclusion is that the 10w40 is not overheating and thinning more than a 30 wt. Now, that was a rather unfair comparison, because we know the 300 I6 is a beast and can run 20w50, so maybe we need to try this with, say a Ford 4.6 OHC V8 and see what the oil pressure says.
 

Tree Hugger

Thread starter
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336
Location
White House, TN USA
Lots of interesting discussion here.. MoribundMan, were those scenarios actual observed events, or just 'thought experiments'? I'm almost convinced to install a thermostatically controlled oil cooler, but... The only cooling effect I can see on overall oil temp (apart from the block temperature which I assume is closely related to the coolant temp, not the ambient temp), is air cooling of the oil pan. I'm as yet unconvinced that that 'accidental' effect is large enough to provide for significant differences in 'overall' oil temperature. I don't know it's not big enough, I just don't know how much the overall oil temp is varying (the exotic temperatures - such as in the cylinder cross-hatchings - are obviously independent of ambient temperatures, so I don't see the relevance of those to this discussion)
 
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23,591
Hey Tree Hugger, The numbers I spilled were not unrealistic, but loosely based on past observations of the various cars I've owned over the years. These numbers do not reflect behavior of any particular engine or car, but rather trends under certain conditions, and they were meant to illustrate my point. heyjay wrote:
quote:
A tire that is properly inflated at +20 C / +68 F will be severely UNDER inflated at -30 C / -20 F.
Well, once you've been driving for a while, the tires will get pretty warm due to friction, even in freezing temperatures. If you drive only short distance around town during winter, then you're right. Ideally, all our cars would adjust tire pressure automatically, something a few high-end cars (and military vehicles) can do. Generally, I overflate my tires always by a few psi, because I find the manufacturer's recommendation overly soft. I prefer crisper handling and the benefit of better gas mileage over marginally more comfort.
 
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11,006
Location
Canberra ACT Australia
heyjay thats why I run Nitrogen in the tyres on both our vehicles. Also they don't leak down as air filled tyres do. Tyres run cooler and hence last longer. For A$5 per tyre it's a no-brainer IMO.
 
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23,591
Hey sprintman, years ago, I used to have my street tires filled with nitrogen. The problem was the cost (ca $15 per tire), and the uncertainty of knowing if the tire pressure was actually correct.
 
Messages
526
Location
Manitoba Canada
quote:
Originally posted by sprintman: heyjay thats why I run Nitrogen in the tyres on both our vehicles. Also they don't leak down as air filled tyres do. Tyres run cooler and hence last longer. For A$5 per tyre it's a no-brainer IMO.
Neat idea. Though I wonder how you adapt a N pressure cylinder to pump into a tire?? Moribundman: Actually, if your tire is half-flat at -35 C, driving around will usually make the bead unseat from the rim. I personally had to change a flat once at -40 and swore I would NEVER do that again. I'd sooner drive on the rim. Jerry
 
Messages
9
Location
Toronto, Ontario
quote:
In most cases, you are not supposed to use a 5W-30 in temps exceeding +10 C / +50 F. For consistent summer operating temps of +20 C / +68 F, most makers recommend the following viscosity: 10W-40, 15W-40, 15W-50, and 20W-50.
Not disagreeing... for the sedans my family own (88 Volvo 740 turbo & 850, 96 Camry V6, 02 Acura RSX-S), all of them only list & recommend 5w30 or 10w30 in the owner's manual. The Volvo lists the 40 weight oil only for extreme conditions like mountain driving and towing. When you recommend heavier oil for summer driving, are you recommeding to go to the heavier end of the manufacturer's spectrum (which in your car is 40 weight; mine is 30) or to go beyond it? The manuals seem to suggest going to heavier weight oils (40+) will cause engine problems and not just reduced fuel efficiency. Thanks! btw, great forum, although now I think I'm getting a little too addicted to learning more about oils. [Razz]
 
Messages
526
Location
Manitoba Canada
Here in North America, the auto makers and the API/SAE have perpetuated this myth that "one oil is good for all seasons and all driving conditions." Most of that rationale has to do with the EPA's CAFE (Corporate Average Fuel Economy). CAFE testing is such that a fraction of a MPG is applied fleet-wide, and the formulae allow the car maker to build CAFE "credits" that offset poor MPG results in other cars/trucks. If you examine the viscosity/temperature charts for other makers in other parts of the world, viscosity recommendations vary quite widely based on temperature. In most cases, you are not supposed to use a 5W-30 in temps exceeding +10 C / +50 F. For consistent summer operating temps of +20 C / +68 F, most makers recommend the following viscosity: 10W-40, 15W-40, 15W-50, and 20W-50. Remember that the so-called "energy conserving" oils will effect fuel consumption by 1-3% max. Usually on the lower end, say 0.5 - 1.5% max. What does this mean for the average driver? Say you have hypothetical fuel economy like follows, then increase it by 1.5%: 10 MPG + 1.5% = 10.15 MPG 20 MPG + 1.5% = 20.3 MPG 30 MPG + 1.5% = 30.45 MPG 40 MPG + 1.5% = 40.6 MPG 50 MPG + 1.5% = 50.75 MPG 80 MPG + 1.5% = 81.2 MPG As you can see, in most cases the fuel economy "improvement" falls within expected statistical variability and will be unnoticed by the average driver. Though this is supposed to make you feel good about driving something like a Ford Excursion with a V10 motor. If you truly want to improve fuel economy, try the following: 1. Buy the smallest car practical, maybe a 3 cylinder with 1.3 litre max displacement 2. For other vehicles, especially pickup trucks, run the smoothest highway all-season tire possible. No lift kit, no aggressive off-road tires. 3. Keep the tires properly inflated the the wheel alignment in spec. 4. Is the air filter clean? Or is it plugged? 5. Spark plugs clean? In my own daily driver, a 2000 GMC Sierra that sees towing duty in summer of +8,000 lbs, I run the following oils: Winter: Mobil 1 0W-30 Summer: Mobil 1 10W-30, soon switching to Mobil 1 5W-40. In my climate, I can see winter lows of -42. In summer, +35 C is nothing unusual. If I try to run the 0W-30 in temps hotter than +10 C / 50 F, my truck's Vortec motor makes a lot of valvetrain noise. Most of that noise goes away running 10W-30. A final thought regarding an oil viscosity: this is rated at 100 C and "low" shearing force, and is a Kinematic viscosity. In most parts of the motor, you will see MUCH higher temps and shearing forces. The HTHS (High Temp High Shear) is quite a bit different than Kinematic viscosity and reflects the effect of shear/temp on oil viscosity. For example, the oil film in the cylinder crosshatch next to the oil control ring may see temps of +600 F. Jerry
 
Messages
526
Location
Manitoba Canada
quote:
Originally posted by Dick in Falls Church: IMO, if you are using a good synthetic, summer vs winter oil is akin to summer air vs winter air in your tires!
Temperature has a HUGE effect on tire air pressure! A tire that is properly inflated at +20 C / +68 F will be severely UNDER inflated at -30 C / -20 F. So you have to carefully check your tires and adjust the air pressure based on season. Hmmm, just like adjusting an oil viscosity based on season. Jerry
 
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