would there be any ill effects when using the mobil 1 5w50 synthetic in place of the mobil 1 15w50,I have been using the mobil 1 v-twin 20-50 for along time and seems to work fine in all my bikes but the stuff is about $13 a litre up here in Canada,would like to use the automotive stuff which is substantially cheaper but walmart only has mobil 1 5w50 up here can't seem to locate the 15w50 anywhere up here.

 

I would not because the base oil is a 5w with a lot of VII's (viscosity index improvers) These are polymeric additives that thicken the oil to a 50w when heated. They tend to dissipate or burn off so to speak and when they start to break down you can lose the protection needed in an air cooled engine. There is a big difference between a 15w and a 5w. You would be better served with a 15w40 HDEO like Rotella or Delo or Delvac or a 20w50 Dino like HD360.

 

It is NOT within the engineering specs of the engine. A 10/40 is the only listed alternative to the 20/50. A 20/60 should be OK since staight sixty is OK above 80degrees F. No 5 wt. is listed, either straight weight or multi grade.

I would NOT use it. Better with a cheap deisel oil (non syn) than a syn that is not up to viscosity specs, IMHO.

EZ

 

NO to 5w50

 

how's about buying some AMSOIL and having it delivered via post office...?

(and no, I don't sell amsoil)

 

thanks for the replies,probably just stick with v-twin 20-50,I have a amsoil distributor just up the road from me and he isn't any cheaper for 20-50 motorcycle oil,most places won't ship oil across the border ,not sure of the reason for this but I found out a while ago when trying to get some redline shockproof for my tranny,it is to bad though because the automotive mobil1 is $32 for a 5 litre jug at walmart and v-twin 20-50 is $12.34 per litre at walmart about half price,but I only have to change it a couple of times a year so I guess it isn't going to put me in the poor house.

 

Just bought Shell Rotella (diesel) T 15-40 at Wally mart for 28.88cdn. Manual mentiond diesel as well as a guy up the street who runs a softtail.

 

You've solved your own dilemmna. The Mobil1 15:50 in the 5-liter jug is 1/2 the price of the 20:50 andyet has more V-Twin additives in its formula than HD's Syn3. Save your money and trust an organic chemist!

 

Can you illustrate this statement? My HD owner's manual specifies a CF-4 or higher API rating. Mobil 1 15w50 only makes a CF rating. The same is true for their V-twin 20w50.

 

It doesn't really specify a CF-4 if you'll read it a bit closer, as the wording is purposefully vague to steer you toward HD-branded oils. It says "If it is necessary to add oil and Harley-Davidson oil is not available, use an oil certified for diesel engines. Acceptable diesel engine oil designations include (emphasis mine): CF-4, CG-4 , CH-4 and CI-4." Note the word "include," which means this is a partial list. I know of no 20w50 with a CF-4 designation except Royal Purple, so if you try to find one you'll likely have a hard time. Feeling bad about not meeting HD specs you'll then run down to your HD shop and buy some Syn3 for $10/qt., or at least that's what they hope you'll do.

I know people who've run oils without a CF designation for years with no trouble.