Why do people run higher weight oil in summer?

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Originally Posted by ZeeOSix
Originally Posted by userfriendly
With all the goo goo and ga ga threads about HTHS viscosity, base oil viscosity etc in the last few weeks, lets talk about post permanent shear high temperature protection.
The PDS tells us how the engine oil performs when fresh, but how about towards the end of the oil drain interval?


HTHS typically follows KV100 fairly well, so if an oil shears down with mileage I'd say the HTHS is also reduced by a similar degree.

That's why I use 5W-30 instead of xW-20. I want HTHS headroom for any shearing, and for any driving conditions that might elevate oil temperature.




THANK YOU!

EXACTLY WHY I go to a NOT a Ford USDM (5W-20) recommended viscosity in the heat of summer, and use a medium HTHSV 5W-30, especially since the way I use my car (NOT a granny driven Camry/Avalon), the fuel diluting 1.6 liter, power dense, direct injected turbo, with a known marginal factory cooling system, and that I use a full bottom of engine/sump covering skid plate during the summer.
wink.gif
 
Originally Posted by ZeeOSix
Originally Posted by userfriendly
With all the goo goo and ga ga threads about HTHS viscosity, base oil viscosity etc in the last few weeks, lets talk about post permanent shear high temperature protection.
The PDS tells us how the engine oil performs when fresh, but how about towards the end of the oil drain interval?


HTHS typically follows KV100 fairly well, so if an oil shears down with mileage I'd say the HTHS is also reduced by a similar degree.

That's why I use 5W-30 instead of xW-20. I want HTHS headrom for any shearing, and for any driving conditions that might elevate oil temperature.



+1 ... Especially with a GDI engine . For my Sonata Hyundai states I can use : 5W20 , 5W30 or 10W30 - that's all ! ... So now I use a "Thicker" 5W30 (M1) in warmer months and a "thinner" 5W30 in the cooler months (PP) as in my GDI engine... I am concerned about sheer towards the last 1/3rd of an oil change as well as film strength - thus I choose the 30W Hyundai recommends instead of the 20W ... Perhaps in a Ford or other makes there is nothing to "error towards" so using a x20W is just fine . It could also be an argument regarding "film strength" comparison between xW20 and xW30 ?
 
I think we over analyze this as well though. The other 99% of car owners are none the wiser to winter vs summer oil, and the majority of those probably couldn't tell you what grade or brand of oil is in the car... "Oh uh... whatever they used at Jiffy Lube." Yet these cars still last several hundred thousand miles.
 
Last edited:
Originally Posted by dailydriver
Originally Posted by ZeeOSix
Originally Posted by userfriendly
With all the goo goo and ga ga threads about HTHS viscosity, base oil viscosity etc in the last few weeks, lets talk about post permanent shear high temperature protection.
The PDS tells us how the engine oil performs when fresh, but how about towards the end of the oil drain interval?


HTHS typically follows KV100 fairly well, so if an oil shears down with mileage I'd say the HTHS is also reduced by a similar degree.

That's why I use 5W-30 instead of xW-20. I want HTHS headroom for any shearing, and for any driving conditions that might elevate oil temperature.




THANK YOU!

EXACTLY WHY I go to a NOT a Ford USDM (5W-20) recommended viscosity in the heat of summer, and use a medium HTHSV 5W-30, especially since the way I use my car (NOT a granny driven Camry/Avalon), the fuel diluting 1.6 liter, power dense, direct injected turbo, with a known marginal factory cooling system, and that I use a full bottom of engine/sump covering skid plate during the summer.
wink.gif



I say do whatever makes you feel good and I am not being critical but I have a side to consider in this debate that I have not seen argued here:

Some engines have hypereutectic pistons which are designed to expand as an engine warms up partly to help with emissions control. This can even be pronounced enough to cause "piston-slap" at cold startup in some applications. Thus, clearances are definitely altered depending on the operating temperature of the engine.

Engineers must be confident predicting this expansion based on temperature and must select an oil that works best for all of the conditions for most applications.

Therefore, it is likely that if there was thinning or whatever, it may even be by design. The pistons expand and the viscosity is supposed to decrease to accommodate it. It could be possible that using a higher viscosity oil messes up their predictions and results in more wear.

I am not saying with any certainty this is true, but if someone with my level of knowledge could come up with ways to experiment on something, I am sure someone who actually knows what they are doing would be able to some pretty darn good testing.

Overall, it seems unlikely to me that given all of the possible variables that could play a part that it is as simple as "its hotter go thicker" or vice versa.
 
Originally Posted by userfriendly
Havoline SAE 30 meets API SN. There are other examples.


It says it is suitable for use in applications that call for SN and SN plus (and earlier) but it is not GF-5, nor Resource Conserving. It also has none of the OEM approvals, because of course no OEM calls for it.

Many of the limits/specifications aren't applicable to monogrades. That can be seen in this document:
https://www.api.org/~/media/Files/Certification/Engine-Oil-Diesel/Publications/17thed1509addendum7rev021218.pdf

So, for example, an SAE 30 or SAE 40 will fall under the "Other Grades" category, since they don't fall into the first column (0w-16, 5w-16, 0w-20, 5w-20, 0w-30, 5w-30, 10w-30) or the last column (Resource Conserving).
This means:
- No upper limit on Phosphorous
- No upper limit on Sulfur
- No gelation index
- No D6335 TEOST

These are not lofty requirements, and don't require reduced levels of "conventional" additives. Ergo, I'd be quite surprised if there was any formulation change in ages. Let's look at the applicable limits for the current standard, and compare them to the past one, which can be done thanks to this document from Infineum:
https://www.infineum.com/media/337535/inf_api_bro_2018_8-14-18.pdf

API SN/SN Plus vs SM
- Sequence IIIG - visc increase is the same, merit has increased from 3.7 to 4.0 for deposits. Cam plus lifter wear is the same.
- Sequence IIIH - visc increase is the same, merit has increased from 3.2 to 3.7 for deposits.
- Sequence IVA - Average cam wear limits are the same.
- Sequence VG - Average sludge (merit) increased from 7.8 to 8.0, rocker arm sludge from 8.0 to 8.3, average oil screen blocking from 20% to 15%. The rest are the same.
- Sequence VIII - Average bearing weight loss is the same.
- ASTM D4683 - HTHS lower limit of 2.6 not present on SM.
- ASTM D6557 - Ball rust test, limit is the same
- ASTM D5800 - Evaporation loss, limit is the same
- ASTM D6417 - Simulated distillation, limit is the same
- ASTM D6795 - Flow reduction max, limit is the same
- ASTM D6794 - Flow reduction max, limits are the same
- ASTM D4951 - Phosphorus max, (no) limit is the same
- ASTM D892 - Foaming tendency/stability, limits are the same
- ASTM D6082 - High-Temp foaming, limits are the same
- ASTM D7097 - TEOST MHT, limits are the same

So it's quite likely these formulations have not changed since at least SM. In fact many of the limits and tests are similar or the same between even earlier specs like SL or SJ, so it could be even longer.
 
Originally Posted by badduxx
I have to respectfully disagree based on my experience with a caveat. I have a vehicle that has an oil temperature gauge.

As per Overkill's comment about thermostatically controlled oil coolers, you and Patman are both right. I've seen both behaviours exhibited. The old Audi 200 Turbo had an oil cooler bigger than the rad and I couldn't get the oil temperature much over 100 C driving full boost for thirty minutes in 34 C weather. Conversely, in the winter, the oil would get sufficiently warm and be at pretty much the same "normal" temperature range under "normal" driving, and I did test the calibration of the oil temperature sending unit, not believing it. The taxis, generally lacking thermostatically controlled oil coolers, exhibited much different behaviour.

Originally Posted by userfriendly
I guess I'm wrong assuming that oil formulators use current additive packages in their mono grade engine oil.

I bet some yes and some no. I'd think at least some would be upgraded, particularly in the nominal PCMO line. Would all monograde HD type oils be upgraded, particularly those catering mostly to obsolete specs? Only a formulator could really tell us all this.
 
Originally Posted by userfriendly
Ironically both Delo 100 SAE 40 and Havoline synthetic 5w40 SN have the same additive package.


You e-mailed them and asked? Just curious how this information was obtained. It doesn't seem that "out there" given what I've posted above regarding the exceptions for oils that aren't GF-5 or Energy Conserving.
 
product # 223726 5W40 SN

density .853
40C 83.6
100C 13.4
P .096
Zn .105
BN 7.3
NOACK 9

product #222404 Delo 100 SAE40

Density .890
40C 145
100C 15.0
P .096
Zn .105
BN 7.2
Base oil NOACK 2
 
Originally Posted by pbm
Because they want to use up their stash of CLEARANCE oils.


Yep. I just put 10w30 in my Accord. Because I got the 5 quart jug for $13....I bought a few of them (6). In the winter, I mix 50/50 this 10w30 with VSP 0w20.....that I also got on clearance.
 
Originally Posted by Patman


...Anyone with an oil temperature gauge will confirm this. Yes the cooling system stays roughly the same between winter and summer but in the hot weather your oil temps are definitely a good 20-30F hotter overall. That's roughly equivalent to going down a grade in viscosity.


I formerly owned one of the hottest running (for coolant and oil temperature) engines: The BMW N54 (3.0L I-6 twin turbo). I had both the stock oil temp gage, and a digital gage reading true coolant temperature from the OBDII (the stock temp gage gave a B.S. reading and was mostly useless).

Coolant temp actually fluctuated more than oil temp (it was actively managed by the ECM). Coolant temps could reach 108ºC (226ºF), although usually when idling or driving slowly. Oil temps could reach 255ºF. My car had the sport package so it had an oil cooler. N54 powered cars without oil coolers could reach oil temps of nearly 300ºF before triggering "limp mode". Yes it was foolish to put a twin turbo engine in a car without an oil cooler. Bean counters are foolish.

Nonetheless, BMW just recommended 5W-30 for these engines. It is my impression that EPA requires them to recommend only the same oil weight that was used to do the fuel economy test. And thinner oil gives marginally better fuel economy.
 
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