Q: does heavier oil really help in summer?

[meep]

Here's the deal... lots of folks here discuss using a heavier oil in the summertime for "extra protection," especially with the advent of all the 5-20 specs. I don't quite understand... here's why:

Unless removed, all cars have the thermostat that regulates flow to the radiator. Except for the old 57 chevy I used to work on, every car I've owned reaches operating temp and then stays there, with no gauge indication of winter/summer differences. (The old chevy actually fluctuated with speed, rpm, etc.)

Granted, the sump will get some air cooling benefit, but unless it's finned, not enuf to be a significant contribution.

So, if the cooling system isn't overtaxed, and the gauge stays put, so internal temps are, say, within a 15F range year around, does a thicker oil make sense?

Mike!!

 

[mikeg5]

its about the viscosity and the heat of your motor.. motor oil will sheer in heat and fuel dillution. correct me if i am wrong guys. my motor calls for 5w30 but in the summer i may run 10w30 bc of the higher temps outside. i cant explain in great detail. look in your owners manual. mine displays the temps and what weight of oil to use inside those temps.

 

[meep]

But that's my point... if the motor temp essentially operates at the same temp once warm, regarding of season, then shearing, dilution, etc remain the same.

Cold Startup is different... a 5/30 would be better in winter than a 10/30... but the '30' is still a '30'.

That said, some 20 users want a 30, some 30 users want a 40... my curiosity is, does this line of thinking really hold any value since op temps would largely be the same?

Mikey!

 

[lostwrench]

Coolant temperature is not the same thing as oil temperature. There are internal engine parts that become far hotter than the coolant temperature.

 

[mikeg5]

thats the same question i have lol.. doesnt make sense does it?? i think it has to do with STARTUP temp rather than the running temp of the motor. on STARTUP the 5w30 will be thinner which is great for cold weather startup and flow.. 10w30 i think flows slightly less on startup, now that said i dont see the big difference other than cold start up.. i would think in the summer it doesnt matter between 5ww30 and 10w30. in winter you want to shoot for the thinner on start up which in most cases would be the 5w30..... as far as the actual weight like 30, 20, 40 or whatever i have no idea. i have two choices of oil in my book 5-30 and 10-30 so those are the only two i will run in my motor

 

[ATS-V]

You're assuming the temps are the same after warm up. The time it takes to reach full temp is winter can be over 20 minutes, which most trips are under this time limit.

The coolant temp is regulated by the thermostat, but oil temps are not and can vary much more than coolant.

 

[JohnBrowning]

Look at it this way. Let's say that at operateing temp and steady state the ideal viscosity at the bearings is achieved with a 40 weight oil. Now on a warm Texas summer sunny day cold start and pumpability,cold crank,flow are not an issue. If that same vechile was in Artic Circle area's in Canada dureing the winter those same issues above would come into play in amajor way. All the bearing seperation and resistance to contact are not going to help you if you shear off an oil pump drive pin or starve the top end for oil since your oil wich represented the ideal viscosity,HTHS etc... at the bearings at operateing temp and steady state has now become unpumpable. So what can we do to make sure it is stupid simple to keep people from destroying the engine while under warranty? I know we can give them a single recomendation for an oil viscoity that will work just fine even if it is not ideal under all situations! So then you get most domestic auto manufactures in the USA dumbing down their recomendation to simply 5W30 almost across the board. Then after they have the mogral hordes trained to blindly only buy and use 5W30 a new player comes a long. New petrolem base stock refineing tech., new viscosity improvers,new addtives etc... allow them to return to the 20Wt. wich was a dismal failure years ago in most aplications if longterm durability was wanted. 5W20,10W20, and 20W20 were tried for a while years ago and they really did not do that well over all. The main push for 5W20 was CAFE credits. No becuase of the inovations mentioned above todays 5W20 protect just as well as most modern 5W30's in all the aplications that call for it from the OEM. Some companies 5W20 is actualy have better HTHS and viscosity numbers then other companies 5W30 and 10W30 products.

GM in particular has said many times that it's disdain for thicker oils has nothing to do with wear numbers and everything to do with cold cranking performance. They often cite that with advent of fuel injection that vechiles will start at tempatures that were unheard of 15-20 years ago. So to make sure that idiots do not kill their powertrain under warranty especialy in colder climats the generic single recomendation in each vechiles manual and oil cap! The only engine to date that GM autorizes the use of 5W20 in though is the engines they were buying from Honda for use in their Saturn Redline models.

 

[Master ACiD]

ok you said all cars have a thermostat. thats fine and dandy but the thermostat controls the water temparture, not the oil temparture. the oil temp is free to go as high as it pleases unless you have a nice little oil cooler with a oil thermostat.

 

[JohnBrowning]

Now the problem as I see it is that too many people are not thinking for themselfs or useing UOA as their guide. A 5W40 or 0W40 is not going to give anyone any grief at all in anything that would ordinarily have a simpleton recomandation of 5W20,5W30,10W30 etc.....So why not get better chemistry,more anti-wear,better HTHS,better TBN and TBN retension???????? These will allow most people to have the best comprimise in their crankcase at all times hot or cold climate within reason of course. Our Canadian friends have to be a bit more selective then most. On that same note I have no problem with someone wanting to run only what is recomended for their vechile just as long as they do not force that way of thinking on me. This after all a website devoted to discussion of oil. It would mute to have a website like this if the prevailing attitude on the site was"Just run what the owners manual recommends!". We have seen this discussion go both ways with equal amounts of UOA to back up the thin v.s. thick debate for both sides.

So in the end this site and many like it are not really about oil,or sports or cooking. They are really about free thinking, exploreing new possabilities, trying to understand different thoughts and idea's on a subject matter and finaly friendship and espirt de corp! This type of site is the modern day equal of the old corner pub!

 

[Bamaro]

A thermostat keeps the car from running too cold, the radiator keeps it from running too hot. In the summer the thermostat will open all the way but the engine can still get hotter so your operating temps are usually higher in the summer. The difference is probably less than 50 deg F though.

 

[flatlandtacoma]

Quote:

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the oil temp is free to go as high as it pleases

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That is very misleading. It is still a water cooled engine. I agree that water temperature does not equal oil temperature. But the oil can't just get hotter on its own without giving up more heat to its surroundings which is then carried off by the coolant, thus regulating the temperature of the oil.

 

[mikeg5]

you are right flat. if the motor is at 150 degrees the oil should be too if not close

 

[Seth]

Quote:

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A 5W40 or 0W40 is not going to give anyone any grief at all in anything that would ordinarily have a simpleton recomandation of 5W20,5W30,10W30 etc.....So why not get better chemistry,more anti-wear,better HTHS,better TBN and TBN retension????????

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5w40 instead of 5w20? I believe going up one weight is fine... but two? Interesting!!

Quote:

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This type of site is the modern day equal of the old corner pub!

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[Mystic]

I never use any viscosity other than the viscosities allowed in the owner's manual of a vehicle. In the case of my Saturn Ion the allowed viscosities are 0W30 and 5W30 in the wintertime, 5W30 is the preferred viscosity, and 10W30 is allowed only in warm temperature. Straight 30 wt. is not allowed and neither is 10W40, 15W40, 20W50, or any other viscosity.

I kind of like using 0W30 in the wintertime. Where I live it can reach -15, -19 on very cold nights in the wintertime, and I have personally experienced temperatures of -28 here. I figure if I use a 0W30 there is a better chance also of the oil actually having some PAO in it.

Evidence has been presented at this website that 10W30 oils may well be not superior to 5W20 and 5W30 oils. If so, why use the 10W30? If the 5W30 is a 30 wt. at operating temperature and if the 5W30 is a superior motor oil, I might as well use the 5W30.

 

[Master ACiD]

Quote:

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Quote:

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the oil temp is free to go as high as it pleases

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That is very misleading. It is still a water cooled engine. I agree that water temperature does not equal oil temperature. But the oil can't just get hotter on its own without giving up more heat to its surroundings which is then carried off by the coolant, thus regulating the temperature of the oil.

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as far as i know ive never seen a watercooled oil pan. hows the oil in the pan going to give up heat to the thermostat or radiator?

factor in that most engines now have oil squirters which cool the pistons, (but heat the oil) and you get see some decently high oil temps.

its not like the oil is going to climb to 10,000 degrees, but the oil temparture is NOT directly or indirectly controlled by the thermostat or radiator. unless you have an oil cooler and an oil thermostat anyways.

heres the next question, how many of you guys have actually measured oil temparture on youre engines? i have.

 

[bonnie john]

not 100% sure, but i think my 1988 isuzu diesel 4wd had water cooling to the oil sump

 

[Eddie]

Water temp can be stable at 195 F. and a hard pushed engine can have an oil temp of 350 F.

 

[Terry]

Mike, NO.

You want a stable oil of at least minimum required viscosity for the application that is maximized for the application in viscometrics AND more importantly chemical composition to provide that protection, sealing,stability, heat transfer, and most importantly lubricity.

 

[Tempest]

Thank you Terry for a definitive answer.

 

[mitchcoyote]

A point for synthetics...