I think because they know we won`t be able to find Diesel oil in 20w50 grade, so we would use the 15w40 in emergency and then go back to buying our oil from HD.

But contrary to what HD wants us to think, most of us know any major brand 20w50 is fine.

 

Your question should be Directed Towards more a HARLEY DEALER then this forums. You WILL GET a better answer to your question from them the Dealer.

Or you can use this answer as " pinch requirement " for your question.
As long as the Diesel Oil you want to us when you find yourself on that Desolate Highway where you only find a place that stocks what ever a person would need or in this case needing some oil in a "pinch" and you find that this store/fill em fast places has only the Diesel Oil on there shelf and that oil " Meets the Appropriate Specifications & Viscosity requirements " of the engine/motor its being used in its safe to use.
Always remember to use the right specifications & viscosity required for your vehicle
even if its in a Pinch...

 

Since Harley also recommends 15W40 I see no need to change to 20w50.

 

Wow really, Here you go Danny boy just a few 20w50 oils, proof's in the pudding below people. not busting your bubble here but info is easy to find "GOOGLE is your friend" on this one. Now the 15w wouldn't be a problem as its good for lower temps for start ups (15w or 20w no big deal)
. But the 40w & the 50w deal yes its a better deal for your engine to use the higher 50w as its formulated for Higher Temps.

Mobil Delvac Super 20w50 Diesel Oil.
Amsoil Syn 20w50 formulated for both Diesel & Gas engines.
Power Plus 20w50 Diesel Oil.

 

OK, now where can you "walk in" and buy it. I would love to use it but can't find it except on line.

 

Keep in mind the oils you use (15w40 or 20w50) is designated for the temps you normally drive in. The first numbers 15w/20w is used for start ups in colder weathers making it easier on your engine, lower number stands for colder temps. The end numbers like 40 or 50 are used for higher temps, the higher the number the hotter your driving environments.

I live in the lower So Cal desert where temps can get as low as 9 deg and get as high as 120+ deg. So you can guess what oil I use its 20w50 as others in this thread or its postings say they use 20w50. My oil brand of choice is Spectro Heavy Duty Golden 4 Synthetic Blend.

 

I can't resist this one- - - wait for it- - - wait for it- - - How about going to your local Mobil Gas Station it would be the first place to start looking for it. Not being a smart a $ $ about this but Mobil brand products are usually found at Mobil Gas stations that's a given.

 

You mean those same dealers who (before Harley sold synthetic oil) told people that synthetic oil couldn`t be used in Harleys because it would cause the bearings to skid...you mean those dealers???

You should be asking the dealer...You`re killin me.

 

Many of us have looked for 20w50 diesel...

Despite what the know it all says, you are not going to walk in to a Mobil station and find Delvac 20w50, unless you are in the middle east or Asia.

Like I said, people will not find 20w50 diesel oil, and Harley wants their customers to think HD oil is the only one to use.

 

OK, since you're so quick with your answers maybe you can show me one closer than 45 miles from Sandpoint Idaho. And yeh, you were/are being a smart ***.