Increasing oil weight for hotter climate?

Messages
5,265
Location
South Carolina
Increasing oil weight for hotter climate will only make your engine to run hotter with no increase in longevity...
Hotter is ok because hotter we are talking maybe 5 degrees, not even a blip between a 40 and 50.
Increasing oil weight within manufacturers recommended 10/40 to 20/50 WILL vastly improve shift quality in shared sump bikes for those that ride in warmer 90 to 110 degree weather vs those that ride in 70 to 85 degree weather.
One size does not fit all for the manufacturers giving you a choice, common sense and repeatable results over and over.

Many motorcycle manufacturers give a choice between 40 and 50, common sense dictates the climate you ride in.
 
Messages
28,354
Location
PNW
Increasing oil weight for hotter climate will only make your engine to run hotter with no increase in longevity...
Engine "longevity" corresponds to engine wear. Go too thin and engine wear increases and therefore engine longevity decreases. If going thinner and thinner makes the oil temperature decrease and engine longevity increase, then why not run 0W-20 ... 😄

Manufacturers never say to use a thinner oil when ambient temperatures increase, because there's a reason for it and it's not to keep oil temperature down, it's to keep MOFT up.
 
Messages
1,174
Location
Cedar City Utah
For me, the main decision for the oils I have settled on is how well the oil maintains shift quality over a longer OCI. I like M1 20w50 V-Twin from experience, however 10w40 4T does just as well. Ambient temps of 100 deg happen here in Colorado for about a month in late June thru late July, so 10w40 suffices very well. Looking forward to sharing my next UOA for M1 10w40 4T, from the ZRX1200. Currently right at 5,000 miles since the last change in Oct 2019. A previous UOA with that oil showed at 5,000 miles the oil had plenty of service life remaining (TBN 6.4), so I’ve told myself I’m going 6,000 miles this time. Hopefully another month or so and I will hit that mark. Shift quality remains high and the sight glass shows oil level right where it was when this OCI began last fall.

With all that has been said, 20w50 has no issue with flow at start up in summer temps so get the thought/worry out of your heads, and would be my choice if the consistent and brutal high temps were the same as what the OP sees in Nevada.
This. A little dated but when I had my Panhead in 71,Reno HD only had straight 40 and 60. I used 60 year round even when it was below zero.
In the morning before riding I put electric heaters against the cases for an hour or so. I hardly stopped long enough for it to cool down during the day.
 
Messages
1,561
Location
Ca USA
Go too thin and engine wear increases and therefore engine longevity decreases. If going thinner and thinner makes the oil temperature decrease and engine longevity increase, then why not run 0W-20 ... 😄

Mercy Zee... 30 grades are never too thin for summer...

We say oil are graded on thickness but oils are actually graded on
flow... a 30 flows faster with less energy than a 40 which means a 30
will increase horsepower and decrease operating temps with no loss in
longevity...

Going by the oil can labeling the difference between a 30 Grade and a
40 Grade is ten grade points but that is NOT 10 grade points of
thickness... the measured viscosity difference between the 30 Grade
and the 40 Grade is only 3.8 centi-stokes of gravity flow measured
by a stop watch... flow is how oil is graded not thickness...
you may believe the difference is 10 grade points in thickness but
that is a personal truth... the objective truth is that the difference
is 3 centi-stokes of gravity flow...

full-45634-35394-viscositytest1.jpg
 
Messages
28,354
Location
PNW
Oils are graded solely on flow... not weight nor thickness...
Of course, it's called viscosity. And as mentioned and talked about constantly in the oil forums, the film thickness between moving parts (the MOFT) that keeps them from rubbing on each other is related to the oil viscosity between the moving parts. As the oil viscosity becomes less (thinner), the smaller the oil film becomes and the more likely for parts to rub and wear. Been that way ever since fluid lubrication was discovered.
 
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