Synthetic M/C Oil
Road Warrior
Joined: Jun 2007
Posts: 1,788
Likes: 4
From: Here
15W vs 20W is not at operating temp but cold flow... That's where the 50 comes into play.
FWIW, on the Mobil 1 website the viscosity rating of the Mobil 1 15W-50 @ 100 Celsius is 18 and per the Castrol website the GTX 20W-50 is 18.09. At 40 degrees Celsius, the 15W-50 is 125 and the 20W-50 is 159.1
Thicker when cold, same at operating temp.
Grand HDF Member
Joined: Dec 2007
Posts: 4,999
Likes: 55
From: Bay Area
Youre right thanks for the correction, it probably wouldnt have an effect then.
Outstanding HDF Member
Joined: Feb 2012
Posts: 2,053
Likes: 39
From: San Diego
Just a little something to throw into this oil post, for those whom have read this far.
Shell/Pennzoil (same company) has released a new oil made from pure natural gas.
It starts out clear and changes to a yellow/orange color when the additives are put in.
Claims that it is better to start out with a clear stock, than to start out with dirty oil that needs to be refined first.
Anyone have insight into this product?
Shell/Pennzoil (same company) has released a new oil made from pure natural gas.
It starts out clear and changes to a yellow/orange color when the additives are put in.
Claims that it is better to start out with a clear stock, than to start out with dirty oil that needs to be refined first.
Anyone have insight into this product?
Ultimate HDF Member
Joined: Jan 2008
Posts: 6,532
Likes: 132
From: SoCal
Oil viscosity is a funny thing, here are some comparisons
Brad Penn Conventional
20/50 HI Perf 40c/159 100c/20
20/50 M/C 40c/167 100c/19.4
Valvoline Conventional
Straight 50VR1 40c/219 100c/20
multi 20/50VR1 40c/181 100c/20
m/c oil 20/50 40c/170 100c/20
Valvoline Syn oils
vr1 20/50 40c/147 100c/20
vr1 20/50NSL 40c/124 100c/17.3 NSL Stands for "not street legal"
m/c oil 40c/162 100/20
Red Line Syn M/C oils
20/50 40c/138 100c/18
20/60 40c/185 100c/23
Amsoil Syn M/C oils
20/50 40c/150 100c/20
60 40c/190 100c/23
As you can see the operating temp 100c(212 F) viscosity for all 50 weight rated oils seem to be pretty consistent at 20cSt. with some variance in 2 products, both synthetics. And the 2 60's are really the same viscosity. But on the 40c( 104 F) ratings there is a wide variance in viscosity at that temp.
EDIT when i did this i did it in columns and it posted like this:arghhhhhhh. sorry
Brad Penn Conventional
20/50 HI Perf 40c/159 100c/20
20/50 M/C 40c/167 100c/19.4
Valvoline Conventional
Straight 50VR1 40c/219 100c/20
multi 20/50VR1 40c/181 100c/20
m/c oil 20/50 40c/170 100c/20
Valvoline Syn oils
vr1 20/50 40c/147 100c/20
vr1 20/50NSL 40c/124 100c/17.3 NSL Stands for "not street legal"
m/c oil 40c/162 100/20
Red Line Syn M/C oils
20/50 40c/138 100c/18
20/60 40c/185 100c/23
Amsoil Syn M/C oils
20/50 40c/150 100c/20
60 40c/190 100c/23
As you can see the operating temp 100c(212 F) viscosity for all 50 weight rated oils seem to be pretty consistent at 20cSt. with some variance in 2 products, both synthetics. And the 2 60's are really the same viscosity. But on the 40c( 104 F) ratings there is a wide variance in viscosity at that temp.
EDIT when i did this i did it in columns and it posted like this:arghhhhhhh. sorry
Seasoned HDF Member
Joined: Jul 2007
Posts: 6,336
Likes: 67
From: SW Minnesota
Not to comment on a syn vs auto oil, but I have to disagree on the 15-50 vs 20-50, the reason being auto technology has gone to very tight bearing tolorances thats why you see 0 wt, 5 wt, 10 and 15w. But harleys are sloppy when it comes to tight tolorances and at operating temps you will get poor lubrication with 15 w at high stress areas Just my .02
Here in Minnesota, we often have COLD morning temps late into the spring and early in the fall (this morning was 42 degrees), but end up with 90 degree afternoons. I personally think the 15/50 oil is better than than a 20/50 for that reason. It will protect better at startup on cold mornings, but offer the same 50 wt protection in late afternoon.
Club Member
Joined: Jun 2007
Posts: 45,429
Likes: 2,898
From: Bedford UK
My owners manuals all say to use a diesel oil if MoCo stuff isn't available, designated CH-4, CI-4 and CJ-4. Both dyno and synth oils are available that meet those.
HD Forum Stories
The Best of Harley-Davidson for Lifelong Riders
7 Surprising Harley-Davidson Products that Are Not Motorcycles
Verdad Gallardo
8 Best Harley-Davidson Motorcycles Ever
Pouria Savadkouei
10 Worst Harley-Davidson Motorcycles Ever
Pouria Savadkouei
Killer Custom's Jail Break Is The Breakout That Refused to Blend In
Verdad Gallardo
Crazy Bunderbike Build Looks Amazing, But Is It Impossible to Ride?
Verdad Gallardo
Harley-Davidson Reveals Super Cool Cafe Racer Concept
Verdad Gallardo
Engraved Rebellion: Inside Bundnerbike's Glam Rock II
Verdad Gallardo
10 Motorcycles You Should Never Buy
Joe Kucinski
10 Things Harley-Davidson Needs to Fix in 2026
Verdad Gallardo
Road Master
Joined: Sep 2006
Posts: 793
Likes: 23
From: AZ
Ok thank you
Oil viscosity is a funny thing, here are some comparisons
As you can see the operating temp 100c(212 F) viscosity for all 50 weight rated oils seem to be pretty consistent at 20cSt. with some variance in 2 products, both synthetics. And the 2 60's are really the same viscosity. But on the 40c( 104 F) ratings there is a wide variance in viscosity at that temp.
EDIT when i did this i did it in columns and it posted like this:arghhhhhhh. sorry
As you can see the operating temp 100c(212 F) viscosity for all 50 weight rated oils seem to be pretty consistent at 20cSt. with some variance in 2 products, both synthetics. And the 2 60's are really the same viscosity. But on the 40c( 104 F) ratings there is a wide variance in viscosity at that temp.
EDIT when i did this i did it in columns and it posted like this:arghhhhhhh. sorry