Why do people run higher weight oil in summer?

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I have seen a lot of people recommend running a 5w30 instead of a 5w20 in summertime. As far as I know, the engine operating temp isn't going to be higher in the summer. If the manual says 5w20 is fine year round, why mess with it?
 
Originally Posted by Whammo
I have seen a lot of people recommend running a 5w30 instead of a 5w20 in summertime. As far as I know, the engine operating temp isn't going to be higher in the summer. If the manual says 5w20 is fine year round, why mess with it?


It will reach that temp faster in the summer and thereby will run at high temp longer.
 
Some Owner's Manuals require a thicker viscosity at higher ambient temperatures. Check your OM. Just look at the viscosity our friends in Australia use....
 
Maybe it's the other way around like me. I tend to run a lower wt oil in winter for faster start up oil flow when it gets extremely cold. In our area that's normally below zero weather. doesn't really matter most likely but is a personal preference. I do know in general most 10wxx weight oil are more shear stable than 0WXX hence part of why I prefer these unless it is getting cold.
 
Because they believe everything they read here.
 
Old habits from when oils were trash. Back in the days when you ran SAEx in the summer and 10W30 in the winter.

Lack of cold starts means you can get away with a 15Wx if you want. You can run cool fleet oils in the summer like DELO 400 SD 15W30.

Thicker oils like 10W30 seem to be disappearing from store shelves. I'll bet there are a few members who have a ton of 10W30 they got cheap that plan to run it in the summer to be safe.

BITOG tradition to ignore manual recommendations!
 
Well I run 10w-30 in the summer its going to cause no problems and lots of times its more available on sale. In fact lots of 5w-30's are thicker.
Like my current 10w-30 Havoline Pro DS was $16.85 a Jug with a $7 rebate. $9.85 OCI with a quart left over for top off isn't bad.
 
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I don't necessarily run a higher weight in the summer, but I do prefer the keep the viscosity spread less in summertime. For example instead of 5w-30, I might run 10w-30.

There's just no need for a 5w, 0w, etc. in my climate in the summer. Since additives / viscosity improvers can break down in the presence of heat, the oil should be more robust without them, or less of them. In no way am I suggesting this is a blanket statement for all oils, it is NOT. Some oils may not have additional components to yield a high viscosity spread, I get that. It's just erring on the side of caution and the plain fact that anything less than 10w is completely unnecessary for most of the year where I live.

And to the OP: The engine oil temperature is greater in summer, without a doubt. Drive your car for an hour in stop and go traffic in July versus January and measure the oil temperature. You will get two very different results! Sure, "operating temperature" or coolant temperature may be the same or similar, but oil temperature will not.
 
Originally Posted by Onetor
Some Owner's Manuals require a thicker viscosity at higher ambient temperatures. Check your OM. Just look at the viscosity our friends in Australia use....
How many modern vehicles say to do that ? Honestly asking. In the 60s, yeah, but today ?

Originally Posted by maxdustington
Old habits from when oils were trash. Back in the days when you ran SAEx in the summer and 10W30 in the winter.
That's my thinking too - automakers did specify to do this decades ago and people are stuck in their ways. Just like changing their oil every 3000 miles...
 
even though your water temps are pretty consistent an oil temp gauge may say differently. unless its a PAO + or Ester oil it gets a lot thinner as temps rise. the spec of xx centistokes its real viscosity at 100c aka 212F is just that, your oil exceeds 212F in various locations in your engine, so a watery 20W may get closer to a 10W but a 30W that gets to a 20W is safer. all oils thin with heat + hotter is thinner even if a true synthetic aka redline + thats why distance racers use thicker oils. check out the great youtube by savagegeese,com oil the fine print! he has other interesting + factual vids as well.
 
I'm running a heavier oil , especially in winter in my Mazda DI engine. With the under 10mile trips my wife makes to work, fuel dilution is high.

I don't like 0w20 and continuous fuel dilution.
 
The engine oil temperature is greater in summer. This is taken into account for an automaker in both engine design and setting their maximum warranty--pairing a grade to the engine. However, the warranty period and terms of acceptable conditions induced by wear in that warranty period may not be to the satisfaction of some consumers, particularly those found on this site. I don't know of many engines that have had catastrophic failure when the end user followed the manufacturer's specified grade, oci, and appropriately retired/ replaced their oil filters, both during the warranty period and long after (and made sure that it was never under-filled.)
 
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Originally Posted by pbm
Because they want to use up their stash of CLEARANCE oils.


LOL the real answer. And mine.
 
Originally Posted by ARB1977
Run what the manufacturer recommends and be done.

And yet you use unapproved Amsoil in your Toyota.
 
Originally Posted by hallstevenson
Originally Posted by Onetor
Some Owner's Manuals require a thicker viscosity at higher ambient temperatures. Check your OM. Just look at the viscosity our friends in Australia use....
How many modern vehicles say to do that ? Honestly asking. In the 60s, yeah, but today ?

Originally Posted by maxdustington
Old habits from when oils were trash. Back in the days when you ran SAEx in the summer and 10W30 in the winter.
That's my thinking too - automakers did specify to do this decades ago and people are stuck in their ways. Just like changing their oil every 3000 miles...

Originally Posted by hallstevenson
Originally Posted by Onetor
Some Owner's Manuals require a thicker viscosity at higher ambient temperatures. Check your OM. Just look at the viscosity our friends in Australia use....
How many modern vehicles say to do that ? Honestly asking. In the 60s, yeah, but today ?

Originally Posted by maxdustington
Old habits from when oils were trash. Back in the days when you ran SAEx in the summer and 10W30 in the winter.
That's my thinking too - automakers did specify to do this decades ago and people are stuck in their ways. Just like changing their oil every 3000 miles...
 
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Originally Posted by Whammo
I have seen a lot of people recommend running a 5w30 instead of a 5w20 in summertime. As far as I know, the engine operating temp isn't going to be higher in the summer. If the manual says 5w20 is fine year round, why mess with it?


Because they have decades of automotive experience. Going way back to when 10W-40 or 10W-30 was what you used in every car. And today's modern engineering and technology does not trump their training and experience. Because they know better than the engineers who designed the motor and specified the fluid.

Viscosity rating, on the higher range for multi viscosity oil, is meant to be the viscosity of the oil at 212 degree Fahrenheit, 100 degree Celsius. Most engines have a cooling system which keeps the engine operating temperature at or below that temperature. We can assume that you are not in a climate where the ambient temperature is 212 F or 100 C.
 
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