I'm in South Florida.
Have any of you Florida folks ever use 10w60 for its better heat protection instead of 20w50?
I've got Amsoil 20w50 in both my 81 shovelhead and my 2010 RK and both have been running just fine.
But seeing as how temps down here can get a bit nuts I'm wondering if I should change.
I see Motul 7100 synthetic Ester 10w60 online.
Your thoughts please.

 

Back when a 5 liter jug was under $50 I used LiquiMoly 10w60 exclusively in my 2012 CVO SG and then my 2014 Limited. Never had any problems. Redline 20w50 now. I live in Texas and ride in the heat.

 

Not sure why your font color is so light as to be barely readable, but here's a copy of it so people can read it.

One thing you should check if you do use 10w 60 is to be sure it has the proper modifiers in it. Oil geeks should chime in here.

 

Quit playing with font color and you will get more replies.

NOBODY on this site has ever experienced a Harley engine failure due to oil viscosity, or needed extra protection when riding in extreme heat.

I put mine through a torture test (unplanned) 2 summers ago coming back through the Nevada, and Idaho deserts at 115*, for 4 days, hitting endless road construction, and the only thing dying was me.

I am a bit of a hypocrite, I use synthetic 20w50 because I like the bike to crank easier in cold weather, but I never worry about seizing an engine, and you would be hard pressed to find anyone who has on here.

Don't sweat it. Run your favorite 20w50, a good synthetic will give you that piece of mind you seek.

 

IMHO.... 20W50 is fine. Motul 7100 10W60 won't hurt, in either engine, especially the Twin Cam.

The Shovelhead and Twin Cam are different engine designs, with different tolerances.

I used to run straight 50W or 60W in my old shovelheads in the SoCal summers... If I owned one today, I would probably do the same...

 

I live in Texas and ride in the heat; many times over 110°F. I use 20W50 and I do not get any complaints from my engine.

 

Run straight 60wt in the Shovel for sure, find something with high ZInc VR1 or Brad Penn oil.

 

If you live further south of Key West then, yeah.

 

A cautionary note about multi-viscosity oils. The wider the range, the more delicate the oil, as a general rule.
So you could find the oil appreciably degraded by the time you're due for an oil change.

Not saying this absolutely will happen. Just something to consider.

 

You need to know what the operating temperature is, not the ambient temp, if you truly want to know if 10W60 is good for your engine.

Oil viscosities are measured at 40*C and 100*C.
20W50 implies 20 weight at 40*C and 50 weight at 100*C.
Actual viscosity of different oils can vary by 20% and still be considered the same weight.

When comparing oils of the same weight, you want higher viscosities. When comparing oils of different weights, you want the highest viscosity within the OEM specifications. That begs the question, does 60W remain too viscous for Harley?

Here's an example based on my data:
Mobil1 V-Twin 20W50
Viscosity @ 40*C (104*F) = 172 cSt
Viscosity @ 100*C (212*F) = 21 cSt

Typical engine temp at 10*C (50*F) ambient: 152*C (305*F)
Typical engine temp at 37*C (100*F) ambient: 175*C (350*F)

Using Reynolds formula to calculate viscosity (HERE) at the operating temperature, we find:
Viscosity @ startup (10*C) = 687 cSt
Viscosity @ 152*C = 5.5 cSt
Viscosity @ 175*C = 3.3 cSt

Let's look at the MOTUL 10W60:
Viscosity @ 40*C (104*F) = 160 cSt
Viscosity @ 100*C (212*F) = 24 cSt
Typical engine temp at 10*C (50*F) ambient: 152*C (305*F)
Typical engine temp at 37*C (100*F) ambient: 175*C (350*F)

Using Reynolds and Vogel formulas to calculate viscosity (HERE) at the operating temperature, we find:
Viscosity @ startup (10*C) = 559 cSt
Viscosity @ 152*C = 7.2 cSt
Viscosity @ 175*C = 4.6 cSt

After all that, you can see @ 175*C (350*F) operating temp, the 60W MOTUL acts comparably to how the 50W Mobil1 does around 160*C (320*F). Essentially, you can use the MOTUL to maintain the same level of viscosity (protection) at temps 30*F higher than the Mobil1.

At the cooler operating temperature of 152*C (305*F), the 10W60 MOTUL acts comparably to how the 20W50 Mobil1 does around 140*C (284*F).

These improved viscosity numbers tell you that there is better protection, but there's always a tradeoff. The pump will need extra energy to move the oil and any other moving components need extra energy to move through the oil. Is it enough to make a difference? You only will notice it in your MPG (and oil pressure). The pump is obviously okay with viscosities from 2 - 600 cSt.

At 10*C (50*F) startup, the 10W MOTUL acts like the 20W Mobil1 at 14*C (57*F). The MOTUL 10W viscosity is lower than the Mobil 20W, which means at the lower temp, the oil will circulate easier, and the pump will pump easier, however, the protective film will be thinner than the Mobil. Is it enough to worry about? Doubtful, given the small temperature difference of 7*F between the two comparable viscosities.

If you made it this far, congratulations! My advice, go for it and let us know what your real-world impressions are.

EDIT: Yes, I understand the oil is not getting as hot as the engine. The same thought applies. Use the 100*C viscosity numbers for a guess at what oil operating temp is.