what is a good oil for breaking in a rebuilt flathead?

[MarcDeSoto]

Now I'm really confused.  The factory shop manual says in the Lubrication section that the first oil change is at 1000 miles.  At that time, drain the 10W oil and fill with SAE 30.  I guess with today's oil that could be 10-30 oil.  Now I'm hearing 100 miles and even 15 to 20 minutes for the first change!  But I guess it's not a bad idea to be extra cautious.  I can't wait to get my solenoid back so I can start the engine again.  If I can get the starter to release as soon as the engine starts, that will be an incredible relief!  

[Sam Buchanan]

I think it would be safe to assume the lubrication suggestions in the manual are totally obsolete, so much has changed in the past 70 years that we now should use modern oils and service intervals. From a practical standpoint it probably doesn't matter which modern oils we use, any of them will be far superior to what was available in 1948 for these extremely simple engines.

[kencombs]

1 hour ago, MarcDeSoto said:

Now I'm really confused.  The factory shop manual says in the Lubrication section that the first oil change is at 1000 miles.  At that time, drain the 10W oil and fill with SAE 30.  I guess with today's oil that could be 10-30 oil.  Now I'm hearing 100 miles and even 15 to 20 minutes for the first change!  But I guess it's not a bad idea to be extra cautious.  I can't wait to get my solenoid back so I can start the engine again.  If I can get the starter to release as soon as the engine starts, that will be an incredible relief!  

Yes, our knowledge of oils and all things mechanical has increased in the last 70some years.  Thus changing recommendations.  

[soth122003]

100 miles with varying speeds = about 3 hours maybe less. plenty of time to get the engine up to temp and break in all the lube points in the engine. Make sure to keep an eye on the oil pressure and run the engine a minimum of at least an hour with varying rpms to simulate driving (if it can't be driven) and get the block up to temp to burn out any moisture build up etc.. in the block.

 

Joe Lee

[LeRoy]

On 1/30/2023 at 12:27 AM, kencombs said:

Yes, our knowledge of oils and all things mechanical has increased in the last 70some years.  Thus changing recommendations.  

This is an understatement. I took a 4 day tribology class a few years ago, when I signed up I didn't think there was any way they could fill 4 days of instruction on the topic of oil. Was I ever wrong, they hurried and still didn't cover some areas thoroughly. They were focused on industrial applications but most all the info was pertinent to any lube/friction situation.

 

Looking back I would have thought the impact of that course on me would be to turn me into an oil snob, just the opposite is true. I find I change my oil less frequently and I worry less about getting the exact product recommended by the manufacturer. The quality of the lube and additive packages has improved drastically. 

 

We found if you run regular oil analysis and use a side stream kidney filter after each run you can safely extend the oil changes 5 fold. It saved many thousands of dollars a year on oil changes and made me much more confidence in the condition of my equipment.

[Sniper]

1 hour ago, LeRoy said:

We found if you run regular oil analysis and use a side stream kidney filter after each run you can safely extend the oil changes 5 fold. It saved many thousands of dollars a year on oil changes and made me much more confidence in the condition of my equipment.

 When I was in wind we could test the gear oil and hydraulic fluid yearly.  We had a bypass filter that ran whenever the unit wasn't making power and an in line filter that ran when it was making power.  The filters got changed yearly.  We would change the gear oil every 5 years regardless, sooner if the analysis warranted it.  I forget the replacement interval for the hydraulic fluid.

[Conn47D24]

Royal Purple break in oil .  Worked out fine.

 

Plenty of assembly lube on internals as I built.