The HD Service Manual for Shovelheads (the Big Twin produced 1966 to 1984) specifies an initial oil change at 500 miles and then every 2,000 miles thereafter. On the basis of experience, I have always started out a rebuilt motor with fresh oil, an oil change at about 50 miles, then again at 500 miles, and then according to ambient temp and use. On a cool day like today (mid-forties to low fifties) the oil temp was right at 200F and the head temp hung right around 345F to 350 F. HD published something many years ago that said every twenty degree increase in temp cut the life of multi-vis oil in half. So if I'm seeing oil temps of 220 I'm not too worried about a 2,000 mile interval, at 240 we're probably looking at sooner.
Truth be told most of these motors leak so much the additives are being continually refreshed anyhow.
I've built more of these motors than I can remember, I think somewhere along the line I realized just by observation that the oil was not doing real well with the initial startup. The new timing gears and new rings on cast iron cylinder walls seemed to eat the good stuff out of the oil rather quickly. You can hear it and feel it in the motor.
So today I ran a new one about 57 miles on the Castrol 20w-50 that is supposed to be special for air-cooled V-twin motorcycles. Never used it before, and will never use it again.
This was stock stroke, new wristpin bushings, Keith Black pistons and rings at 0.0025" on an appropriately flex-honed cast iron cylinder wall (fitted to size with Sunnen stones, old nomenclature might have been AN-300, not sure), Kibblewhite valves in cast iron intake and phosphor bronze exhaust guides, all sealed, and new timing gears, Andrews BH cam and Jim's Machine pinon gear, lash fitted perfectly. Crank pin, rod big end rollers, and right main rollers new, fitted at the middle of spec or slightly tighter, all within 0.0002" of the target.
Started the bike and shut it off in a few seconds, let the ring edges cool. Started it again, run for 30 seconds and off to cool. Then a minute or two and off. Then a one-mile ride and off, cool. The rings seated in the first hundred yards, no mistaking it. Cool overnight, careful warm up, and the 57 mile break-in ride today. Speed varied, two short hops of about a mile or two with a shutdown, easy road miles generally hanging around 45-50 mph, some backing down from 55, plenty of variance in rpm and a lot of throttle activity oriented toward good oil scavenging.
By the time I got back, the degradation of the oil was unmistakable. The motor did not sound like what it should when the lubrication is right. I have no idea what happened to this oil, but it looked like [censored] when I drained it out. I'm sure someone here will warn me about the necessity of oil analysis. I understand, I used to run a small fleet, we sent out samples on everything that had anything to do with our class 7 and class 8 trucks. Not happening on the motorcycles, at least not today.
So I drained out the 20w-50 Castrol, replaced it with 20w-50 Rev-Tech, and the motor sounds great. Seriously, you could not miss the difference.
Now I know there are a lot of genuine experts here, and I am most grateful for the wisdom shared here. Mostly I just read and learn. But the reason for my question today is this; I would have thought that any of the premium motorcycle oils today would be enormously better than anything that was available 35 years ago. But that's not what I saw today.
This oil just simply turned to [censored]. What happened?
Next question: S&S Cycle strongly recommends Mobil 1 Synthetic 20w-50 in their performance motors. I've tried it on a couple of motors, but it is too soon to tell how it is really holding up. What do you think about that oil?
Thanks to all in advance.
[edited to correct Rev-Tech viscosity]
Truth be told most of these motors leak so much the additives are being continually refreshed anyhow.
I've built more of these motors than I can remember, I think somewhere along the line I realized just by observation that the oil was not doing real well with the initial startup. The new timing gears and new rings on cast iron cylinder walls seemed to eat the good stuff out of the oil rather quickly. You can hear it and feel it in the motor.
So today I ran a new one about 57 miles on the Castrol 20w-50 that is supposed to be special for air-cooled V-twin motorcycles. Never used it before, and will never use it again.
This was stock stroke, new wristpin bushings, Keith Black pistons and rings at 0.0025" on an appropriately flex-honed cast iron cylinder wall (fitted to size with Sunnen stones, old nomenclature might have been AN-300, not sure), Kibblewhite valves in cast iron intake and phosphor bronze exhaust guides, all sealed, and new timing gears, Andrews BH cam and Jim's Machine pinon gear, lash fitted perfectly. Crank pin, rod big end rollers, and right main rollers new, fitted at the middle of spec or slightly tighter, all within 0.0002" of the target.
Started the bike and shut it off in a few seconds, let the ring edges cool. Started it again, run for 30 seconds and off to cool. Then a minute or two and off. Then a one-mile ride and off, cool. The rings seated in the first hundred yards, no mistaking it. Cool overnight, careful warm up, and the 57 mile break-in ride today. Speed varied, two short hops of about a mile or two with a shutdown, easy road miles generally hanging around 45-50 mph, some backing down from 55, plenty of variance in rpm and a lot of throttle activity oriented toward good oil scavenging.
By the time I got back, the degradation of the oil was unmistakable. The motor did not sound like what it should when the lubrication is right. I have no idea what happened to this oil, but it looked like [censored] when I drained it out. I'm sure someone here will warn me about the necessity of oil analysis. I understand, I used to run a small fleet, we sent out samples on everything that had anything to do with our class 7 and class 8 trucks. Not happening on the motorcycles, at least not today.
So I drained out the 20w-50 Castrol, replaced it with 20w-50 Rev-Tech, and the motor sounds great. Seriously, you could not miss the difference.
Now I know there are a lot of genuine experts here, and I am most grateful for the wisdom shared here. Mostly I just read and learn. But the reason for my question today is this; I would have thought that any of the premium motorcycle oils today would be enormously better than anything that was available 35 years ago. But that's not what I saw today.
This oil just simply turned to [censored]. What happened?
Next question: S&S Cycle strongly recommends Mobil 1 Synthetic 20w-50 in their performance motors. I've tried it on a couple of motors, but it is too soon to tell how it is really holding up. What do you think about that oil?
Thanks to all in advance.
[edited to correct Rev-Tech viscosity]
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