The Stovebolt Site Forums The Shop Area Engine Shop Break in oil

I need to buy break in oil for my 54 235 engine that I had rebuilt recently. What viscosity would I use. Normally put 10w-30 in it. So would I use 10w-30 that is a break in oil?

I don't believe such a product exists these days.

Well there is, it has a lot of zinc in it.

I've used Brad Penn Penngrade1 30wt Break-In Oil with good results, switching to 10W30 after break-in.

And yes, as you know, there are lots of 10W30 break in oils available. A quick search at Summit brings up 10W30 break-in oils by Comp Cams, Royal Purple, Driven, Lunati and so on - but I've never tried them.

I have used Red Line Oil's Break-in additive in a more modern engine that I intended to run Red Line Oil products after break-in, and that worked well, also.

"Break-In Oil" should probably be sold by somebody named Barnum. I'd suggest Diesel-rated 15W-40 with a little ZDDP additive for the initial 20 minute 2000 RPM run-in to establish the cam/lifter relationship, followed by 10 accelerations from 30-50 MPH in high gear to seat the piston rings. The engine is now officially "broken in". You can either waste the original oil fill, or run it until it's time for the first routine oil change. I'm not a fan of 10W-30 oil in a stovebolt at anytime.
Jerry

I have used break-in oil as described by Jerry.
But, I have only rebuilt a few engines.

I have a 1954 235 engine rebuilt by an experienced professional builder and he used a multi-grade Brad Penn break-in oil.

GM indicated in late 1954 (in a CHEVROLET SERVICE NEWS) that multi-grade oils could be used in the high-pressure 235 engines. 5W-20 to 10W-30 grades were recommended, depending on the lowest anticipated atmospheric temperature.

I use 10w-40 or 15w-40 after break-in.

The gold standard for many years was GM’s EOS (engine oil supplement). You can still get it but it’s not the same formulation. The good EOS turns up on eBay every once in a while but when it does, it’s always at a premium price.

I switched over to Bradpenn’s break in oil and have use it on quite a few rebuilds without a single failure. The brand is now called Penngrade but it just a name change. There are a couple of other companies that make a specific oil for breaking in a new motor, Driven I think offers one. But frankly the bradpenn has been a very good product and no failures so I stick with what works. Give it a go I think you will like the quality.

I use Valvoline VR-1 30 weight. Extra zinc in it.

I use Bradpenn or Pengrade and have never had a failure, I also stick with what works. 30 w then switch to 10w30. If you can't afford the better oil for break-in, you are in the wrong hobby!

I know everyone has their favorite oil for multiple reasons. Always a hot heated debate over the best ...........

One thought.........a “failure” of a new or rebuilt engine is not going to from the choice of the break in oil. It’s going to from a mistake, error, choice or decision made during the build or rebuild process.

Choosing the best or most expensive oil known to man is not fix those mistakes, errors, choices or decisions.

I agree it is a topic of debate but I will very respectfully disagree with you Showkey, especially when breaking in a flat tappet cam. You can wipe a lobe at break in using the wrong oil. Too high a viscosity, not enough zinc, any number of things related to lubrication, other then mistake or error. Or you can use an oil that is too slippery and prevents the rings from seating. But why take the chance. GM used and still uses their own version of break in oil for the same reasons that we do, to protect the motor at break in. So if anyone is asking my opinion, after you have spent considerable dollars rebuilding a motor, you should not skip using oil specifically developed for breaking in a new motor just to save a few (very few) dollars. Give yourself the very best chance of having no issues with a new motor. Just my thoughts on the matter.

5W30 if you can find it.

I talked to the machinists that did the machine work. He got me Driven oil 5w-30
Because of the tight tolerances. So that’s what I’m using.

If there's any clearance inside a Stovebolt six that needs 5 weight oil, it's built WWWWAAAAAYYYYY too tight!
Jerry

According to the original 1948 owner's manual, my truck was delivered new with 10W oil to be used for the first 500 miles. After that, these were the recommendations depending on the lowest temperature the truck might see.

Down to 32 deg: 20W or 20
32 to 10 deg: 20W
10 to -10 deg: 10W
Below -10 deg: 10W plus 10% kerosene (must not have had 5W in those days)

I use 10W-30 Mobil 1 year round. That was also my break-in oil for the 261.

The manual also has a nice explanation of the difference between the 20W and 20 designations (viscosity determined at different temps but that's probably on the internet).

Straight 30 weight: start the engine, then go back and finish your breakfast before the oil reaches the last lifter.
That's why 5W.