Break-in oil for rebuilt 6?

['41 Fat Bottom Girl]

Going to be using Valvoline VR1 Racing (high Zinc) synthetic oil in my '41. 

For engine break-in of the rebuilt flat 6, would this be a good oil for the break-in period as well?

Thanx!

[RobertKB]

You can buy a specialty oil designed for break-in. When I rebuilt the flathead in my '51 Dodge, that is what I used and changed it after 500 miles. Can't remember the brand, however, but most automotive stores should carry it.

Edited August 23, 2020 by RobertKB

[Sniper]

the primary driver for zinc and other anti-wear additives is spring pressure, we have minimal spring pressures so generally speaking whatever oil that meets current standards is adequate for break in or normal use.

 

https://tech.drivenracingoil.com/zinc-in-motor-oil/

[desoto1939]

Jegs sells Lucas Engine Breakin Oil SAE-30 with high zinc  found it on the internet cost is not cheap $32 but this will provide you will the intital protection when breaking the oil and then chnage over to what ever you want to run after the breakin period.

 

Can we assume that you will have an oil filter on the engine? If so then a multi weight motor oil is even better even though the original filter were just a flow through filter unit it gives some protection.

 

Also redline makes an additive bottle of breakin oil that you add to your oil durin g the initital start up and then drop the oil after the breakin.

 

Rich Hartung

[NickPickToo]

I used a standard 10W-30 but also added the zinc separately.  Plan to switch to AMS oil with Zinc after about 600 miles.  

[greg g]

I would think you would want an oil with a not very heavy additive package.  Especially friction reducers, modifiers.  You need a bit of friction to seat rings clean up the high spots left after honing. I used 5 quarts of straight non detergent SAE 30.  Ran it for about 1200 miles, in the words of the machinest, drive it like you stole it.  Then I changed to 15w40 all fleet oil from tractor supply.  Last oil change the shop used 15w40 Rottella.  47000 miles and still showing the same oilpressure as when freshly rebuilt. I add about a pint 750 miles. Which is mostly due to leakage.

[Loren]

This is one of those questions that comes up regularly. I think of it as the old question of how many angels can dance on the head of a pin?

The fact is today motor oil, any motor oil is better than what you could buy in say 1941.

So you can't hardly go wrong. I read many places that oils no longer contain zinc and so there is a lot of handwringing over that.

To tell you the truth I am not sure oil manufacturers ever intentionally put zinc in the oil. There may well have been some in there but I have no evidence they knew about it. Lead on the other hand got in the oil from combustion of Tetra Ethyl Lead in the fuel. (That's the grey gunk in the bottom of an old oil pan) Lead had lots of lubricity especially in places that got hot like valve seats. So if zinc has a place in an old engine it likely is to replace lead.

I am facing the assembly of my engine in the next week. I think if you use a high quality assembly lube with zinc you're covered. Too much of a good thing is never better only toxic. If you are using fresh gaskets and seals I would think you don't need to worry about synthetic oils eating them.

Stuff has gotten better. So as long as you use oil that is commonly available and not the exotic lubes from Europe and Asia, the rings will seat and the gaskets won't leak.

I used to live near a facility that reclaimed oil. The owner had me convinced he made a very good product. So I bought it by the drum and never had any lubrication issues.

There are companies (Caterpillar for one) that advocate drain oil testing. Once you pick a lube oil and stick with it you could get your drain oil analyzed from time to time. That might put your mind to rest.

[9 foot box]

   My rebuilder supplied me with 5 quarts of Driven BR30, 5w-30 break-in oil. They make other weight oil, also.

[Dartgame]

Main reason for higher zinc content in motor oil is to stop flat tappet lifters from wiping out the cam, it's a high shear high pressure lubricant additive. The EPA mandated a change in motor oil formulations that required the reduction of zinc content a number of years ago. Most if not all engines now use roller lifters which do not require the same amount of zinc as a flat tappet motor. Reason for this change were concerns over zinc affecting catalytic converters, trace zinc in the exhaust can apparently ruin the catalyst in converters, over an extremely long time, (over 100 K miles). 

 

I have a number of hot rod V8 flat tappet motors and use a zinc additive ZDDP plus in them. For the old flat head motors the valve spring pressure is so low that zinc is really not a requirement. And don't forget most oils still have some amount of ZDDP in them, it's just been reduced from the flat tappet era oil level.

['41 Fat Bottom Girl]

Thanx, this is what I will do:

I had VR1 Racing high zinc oil in the engine for the first hour of run-in time then drained it and cleaned out the filter canister to remove the worst of the metal particles. New filter and Royal Purple break in oil next. Will run that for about 200 miles to finish beak in, then will change to VR1 Racing high zinc full synthetic for 1000 miles and drain again. After that beak in complete, new filter and VR1 again for regular 3,000 mile oil and filter changes. Sounds like this is a reasonable approach.

Good tech article, Sniper, and thanx everyone for the experiences and advice.

Best Regards to all.