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

Wonder what kind of break in oil is recommended for a new build 1962 235 chevy? I have a zinc addative to add to the oil for cam.
John Paul

This subject has been beat to death. Try doing a search using the search function just above this post. You will get hundreds of hits. The search function is your friend.🛠

If it’s any help, I used brad penn breakin oil for my most recent 261. It’s now called penn grade. My 261 is very modified. 59 block, 302 gmc Rods, cut down 302 Bearings, venolia forged pop up pistons, Schneider solid lift cam with 492 lift, 280 seat pressure, big valves, porting, polishing, smith brothers push rods and rocker adjusters, all kinds of stuff. The motor broke in perfectly with the brad penn breakin oil and has run like a top notwithstanding my sometimes hard driving, lol. So, I prefer it and will use it on the next 235 motor that is in the works.

For many years I used Kendell oil (Bradford, PA) and a container of GM EOS but the EOS sold today is a different formula. As below, you can use oil plus a ZDDP package but the break in oil is still different in that it has an enhanced additive package just for the initial start up. One of the reasons I prefer the BrandPenn/Penn Grade is that it is refined at the same refinery that the old line Kendal oils were refined at and the oil is still the clingy green stuff that served me well over the years. PA crude stock which I am told is a better grade lubricant, a partial synthetic package, a break in additive, and no issues with break in. Fourth motor on the stuff. Also, last spring when I took the valve cover off for a spring adjustment, stuff was still on the rocker arms and springs so I thought that was a pretty good sign.

Others have their favorites, in the end it may not matter, but I go with what has worked for me anyhow.

John, as you will find, you will get hundreds of opinions on this. The motors I build all get Brad Penn or Comp Cams break-in oil. The cost is not a factor to me, so paying more for the oil I know works is fine for me and my customers. I like these two oils because it's premixed do the job it is intended for. I was just buying name brand oil and adding a bottle of additive which was working, but have since gone to dedicated oil. I can get the CompCams oil local so no need for shipping or special orders.

On your 235, if it's a stock rebuild with factor spec'ed cam, you will have little trouble and most likely could get away with a good quality standard oil. The cost of the additive in the long run is nothing, so I would use it anyway. I also leave the break-in oil in till I get a few drive miles on the engines, as the rings and cylinder walls are not broken in till they are loaded and unloaded by driving. I then change oil and filter, in your case the filter may be an option.

Cam design, valve spring pressure, and lifter type all determine the load placed on the camshaft, stock 235's have very little! And remember, the only way a camshaft lobe gets oiled is by splash off the rods and crank, so get the rpm up ( 1500-1800 rpm ) and let it break-in, then idle down and adjust. If it fires up and runs, let it go, worry about adjusting later. And the most important part is to have a quite exhaust system so you can hear whats going on. The second important item is to have a garden hose handy to cool the radiator, once you start the break-in, try not to stop. I have plumbed the garden hose direct to the water pump and didn't even use a radiator. I just kept adjusting the water flow to keep the temperature around 160-180. I had a thermometer in the upper outlet hose running out into the yard.

Joe

I use Valvoline VR1 SAE30 combined with a bottle of ZDDP.

I am very curious as to HOW LONG people leave break-in oil in the engine, as while it is all good and fine to get the cam and lifters broken in properly, having anti-scuff additives in the oil will make it difficult, if not impossible, for new rings to bed in.

I have Brad Penn Break in oil 30 wt + ZDDP additive in mine right now, and have already run through the entire camshaft break-in procedure, as well as taking it out on the road a few times to seat the rings, only to realize that the rings aren't seating as well as they should, and am suspecting all the slippery stuff I assembled the engine with, plus the break in oil, plus the ZDDP, might be a bit much for the cylinders to get a chance to wear in properly.

Aircraft piston engines use straight mineral oil to seat the rings after an overhaul, or multi-weight ashless dispersant, but anything with an anti-scuff additive is avoided at all costs during break-in....and these engines have flat tappets. It sure gets the rings seated properly.

Should the break-in oil be tossed after the cam run-in? That would make sense to me....

The first number (if there is one, before the "W") determines how quickly oil pressure reaches every part of the engine. Small number = faster, every time the engine is started from dead cold.
Unless you can pre-heat the engine water (transfer from a running vehicle, or tap your house line) and pre-heat the oil I wouldn't use anything heavier than 10W30.

I have always left the break in oil in the motor for 100-150 miles then I change it.

I change the oil right after the break in, As and aside, I also change oil in a new car after about 250 miles, as well as transmission oil. I do heavy industrial maintenance for a living, I always change the oil in new equipment very soon. I have very few failures. Gear boxes are bad, you always get a lot of metal the first time. But trying to clean out a contaminated hydraulic system is purely mean.