HarleyTechTalk

In a Evo engine anyone know of problems using Shell Rotella T4 15W-40 oil?? I've always used Castrol 20-50 Motorcycle oil.
Thanks

Follow your owners manual or service manual.

In any brand you like, synthetic or dino oil. They all work just fine.
 

It has been a few years since I've had a Harley but I believe the manual says that in the absence of the specified oils diesel oil, 15W-40 can be substituted. You guys have it easy Moto Guzzi specifies 10W-60. Not available everywhere to say the least. O'Reillys keeps 10W-60 Castrol in stock which is the recommended brand.
kk

Quote from: Moparnut72 on March 31, 2024, 06:06:17 AMIt has been a few years since I've had a Harley but I believe the manual says that in the absence of the specified oils diesel oil, 15W-40 can be substituted. You guys have it easy Moto Guzzi specifies 10W-60. Not available everywhere to say the least. O'Reillys keeps 10W-60 Castrol in stock which is the recommended brand.
kk

Liqui-Moly 10w-60 is available on Amazon.

Quote from: dubepj on March 30, 2024, 02:22:24 PMIn a Evo engine anyone know of problems using Shell Rotella T4 15W-40 oil?? I've always used Castrol 20-50 Motorcycle oil.
Thanks

Can it be used? Yes.
But why?  It is not the recommended weight.
Is the 20w-50 not available?
Are you running in extremely cold weather?
Are you trying to save a dollar?

Somewhere along the line H-D has sneaked in a change.  i just looked at my owners manual (all 1999 models) and it included 10W40 for the lowest ambient temperature of <40°F.  Lowest ambient temperature of >40°F was 20W50.  Now I know back in 1999 Evo engines were still used in Softail models, but my service manual, which is specific to touring models with twin cams at the time also included the 10W40 with the same temperature constraints.  That suggests to me that 15W40 is not out of the range.

That being said Mobil1 15W50 (yes 50) oil is all I have used for the past 12 years or so and about 80000 miles and it has apparently performed perfectly in my engine. I use different lubes for the transmission and primary as do many others. Mobil1 15W50 is not a motorcycle rated oil but everything I have ever read suggests motorcycle oils are an absolute necessity only where they are used in "one hole" applications (you know where you cannot separate the engine from the primary and transmission).  There many lighter weight car oils with friction modifiers that can play havoc with wet clutch slippage, but again that is not an issue with a Harley as long as you keep the oil in the engine and not in the primary.  Anyway don't just take my word for it, read on.

https://www.ducati.ms/threads/the-case-for-using-mobil-1-15w-50-automobile-oil-in-a-motorcycle.74198/

I suspect you will be fine with your 15W40 in an Evo engine, Just my 2 cents worth.

But based on what you posted, it's recommended for below 40° F, correct?

QuoteBut based on what you posted, it's recommended for below 40° F, correct?

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The way I thought it meant was 10W40 could be used below 40° but 20W50 should not be used below 40°.  The table seems to be comparing ease of starting in cold weather.  I did not think that 40° was the upper limit for 10W40 oil, but I could be wrong.  Anyway I have never used 10W40 in my bike, just 20W50 and 15W50. 

I agree that running a lighter weight in under 40° F weather isn't harmful. I just don't want the OP to think its a good solution for warm weather. That 40wt will break down in an HD much sooner than a 50wt or 60wt oil.

When we've experienced really hot summers here, like +90° F, I run 20w-60 or straight 60wt.

I ran across these oil weight recommendations from S&S. It makes perfect sense to me.


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