Getting ready to start my 239 and was wondering does anyone have a recommendation for Break in oil.

Summit Racing has several from different manufactures. Since this will be a first for me I have no idea if one is better than the others for our engines.

Opinions?

Dan Sokol
Goodyear, AZ

 

Did you have it rebuilt? Is it a new cam, stock or high performance, or did you use new lifters? If you have a hi-po cam and new lifters, was cam lube applied during assembly?

Flatheads have very low valve spring pressures. Not much concern about ZDDP/zinc like on OHV engines. As long as you use a high-quality oil, plain old 10w30 from a reputable manufacturer should be fine. If you want some extra assurance, there are plenty of $15/qt high zinc oils out there to choose from. Here is a very interesting read (get some coffee, it's long!). He tested nearly every kind of oil out there, with some surprising results. Summit's oil didn't fare very well, BTW.
https://540ratblog.wordpress.com/

An excerpt regarding break-in oils:
"Break-In oils rank between number 102 and number 183. But, if you omit the highest ranked Break-In oil which is far more capable than the other Break-In oils, the rest only rank between 144 and 183. So, if you are looking for outstanding wear protection during break-in, you will be extremely disappointed with most of these oils. Because they are not formulated to prevent wear, they are formulated to allow the parts to quickly “wear in”, which is totally unnecessary. This is because newly manufactured parts will have a surface that “microscopically” looks like peaks and valleys. The loading on those tiny little peaks, will be EXTREMELY high, because the load is not spread out across enough surface area to support the load. And no motor oil made by man can stop those peaks from being very quickly worn down, thus leaving a smoother surface that will distribute the load across a surface area large enough to support that load.

That makes it is physically IMPOSSIBLE to stop parts from wearing-in on their own, no matter what oil you run. And we’ve seen that for many years with factory filled synthetic 5W30 Mobil 1 (which is one of the top ranked oils regarding wear protection capability) in countless thousands of brand new vehicles, that always break-in their components and seal their rings just fine. That means so-called break-in oils are completely unnecessary. And the poor wear protection provided by most break-in oils, can put a flat tappet engine in serious danger of wiping lobes. No matter what anyone tells you, for roller lifter engines or for flat tappet engines (no matter how wicked they may be), it is best to use a highly ranked oil, no matter how much zinc is in it, for BOTH break-in and after break-in. In fact, the SAME highly ranked oil can be used for both purposes, meaning you can choose a single highly ranked oil and stay with it from first fire, on."

 

It is a completely rebuilt stock motor. New everything with 30 over pistons.

So according to this guy, our flat tappet engines don't NEED special break in oils, just regular what we are gonna use oil.

On the Dodge truck forum (I am also working on my Grandfathers '40 1 1/2 ton) someone posted a thread and said NAPA is basically the only company who haven't changed their formula. Same as it ever was........

So if I use regular 30 weight during break in, I should have no issues.

Anyone else have a different opinion?

Thanks.