1946/47 Harley Davidson Trike Engine Oil?

[LargeCarManX2]

This Harley Davidson engine is a 1946/47 45cube or 750cc V/Twin Flathead engine. The following Grades are the spec of the day.

40 degrees and below....58grade

40 degrees and above....75grade

Severe duty ............105grade

Any ideas on what type of oil to run? I would think a straight grade would be best due to the year.

 

[1999nick]

I would consider using Harley Davidson 20W60 motor oil, or equivalent. This would be preferable to a straight 60 weight. Much easier starting when cold.

 

[BigCahuna]

I believe those old spec's are really, 58=50 wt, 75=60wt, and 105=70wt. They did it funny in the old days.,,

 

[Johnny]

Big, you are correct. Back in the early 80's I sold a lot of 60 & 70 weight aircraft oil to the local Harley club where I lived.

 

[LargeCarManX2]

Thanks for the answers gentlemen.

 

[G-MAN]

Originally Posted By: LargeCarManX2
This Harley Davidson engine is a 1946/47 45cube or 750cc V/Twin Flathead engine. The following Grades are the spec of the day.

40 degrees and below....58grade

40 degrees and above....75grade

Severe duty ............105grade

Any ideas on what type of oil to run? I would think a straight grade would be best due to the year.


When this bike was made Harley listed the viscosity of its oils in Saybolt (SUS) @ 210F:

58 = heavy 20 wt or a light 30 wt.
75 = 40 wt
105 = 50 wt

Harley's oil recommendations for its modern bikes really haven't changed all that much. They come from the factory with 20w50 now, which covers all the ranges of the Grade 58, 75, and 105.

In your bike, if the engines is in good shape, I'd run any good modern 20w50 and be comfortable.

 

[BigCahuna]

I don't think Harley ever recommended using 20 or 30 wt oils in their bikes.For today's bikes Harley recommends using 10/40 wt oil when the temp is below 40 degrees, and 20/50 above 40 degrees.Those numbers, 58,75,and 105 were their part numbers for 50, 60, and 70 wt oils.,

 

[G-MAN]

Originally Posted By: BigCahuna
Those numbers, 58,75,and 105 were their part numbers for 50, 60, and 70 wt oils.,


What a crock. Those numbers are "grades" in SUS viscosity.

 

[BigCahuna]

Well, try to find some 30 wt Harley oil.,,

 

[G-MAN]

Originally Posted By: BigCahuna
Well, try to find some 30 wt Harley oil.,,


Modern Harley oils are not offered in straight 30. However, I was up at the Wheels Through Time museum a week ago and Dale has a nice vintage oil can display, with some of the cans unopened and still full of oil. Harley did not list the viscosity on its cans in the 30s, 40s, and 50s in SAE viscosity grade, so you won't see SAE 30, SAE 40, or SAE 50 on those old cans. What you do see is Harley's "grades" which are given in Saybolt (SUS) viscosity. The equivalent SUS to a SAE 30 would be Harley's 58 Grade.

 

[BigCahuna]

This isn't from the Harley manual, but they quote from it.http://www.oilsandlube.com/Harley-Amsoil%20Oil%20Chart.htm.Like those cans have no weight on them, still no mention of 30 wt oil ever being recommended by Harley.

 

[G-MAN]

Originally Posted By: BigCahuna
This isn't from the Harley manual, but they quote from it.http://www.oilsandlube.com/Harley-Amsoil%20Oil%20Chart.htm.Like those cans have no weight on them, still no mention of 30 wt oil ever being recommended by Harley.


Harley's 58 grade is a 30 wt. And the grade is printed on the top and back label of those cans.

Even back in the 30s and 40s Harley was a master at marketing. Everyone else's viscosity was listed in SAE so what did Harley do to give the impression that their branded oil was something unique and what had to be used in a Harley engine? They listed their viscosity in Saybolt (SUS) which gave the impression that what was in the cans was something special and different from any other lubricant.