Dulynrod 66cuda
Member
I rebuilt 71 dodge 360, how long should I run it before I change the break in oil ?
break in oil change
- Thread starter Dulynrod 66cuda
- Start date
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Opinions vary. Some people run it for a couple thousand miles. I prefer to drop it out as soon as the camshaft and or rings are broken in. On modern engines with modern oils that's normally in about 30-45 minutes.
mopar head
Well-Known Member
Expensive as mine was, I ran it the max recommended. 500 mi. 
Broke cam in on new 340 build, changed oil and filter. Waiting to reach 500 miles then will change again. But i always use Shell Rotella 15/40 and Lucas ZDDP All the time.
Newbomb Turk
Well-Known Member
The problem is mostly how the bored are finished.
If the hone is competent, once the cam is in (if it’s not a roller) and I have some light check out pulls on it I get the break in oil out.
I’ve found that after 5-6 power pulls the break in oil starts losing pressure and and the pressure curve looks funny.
I don’t wait for that to happen any more. That’s a sign the oil is in distress.
Also there is a very limited, very small detergent package used for that oil. It’s also almost always a single grade oil. So I think it’s not practical to leave an oil formulated for break in longer than absolutely necessary to get break in done and then get rid of it.
If I am doing an engine in the car once the break in is done I drive the car through a good heat cycle, maybe 20 minutes under varying load and then take it out.
The issue is how the bored are finished. If the cylinders are honed using “modern” techniques the rings may take longer than just a cam break in cycle.
The end user should recognize that and ask the engine builder how long the rings should take to come in.
If he says 500 miles get your parts and find a better shop.
If the hone is competent, once the cam is in (if it’s not a roller) and I have some light check out pulls on it I get the break in oil out.
I’ve found that after 5-6 power pulls the break in oil starts losing pressure and and the pressure curve looks funny.
I don’t wait for that to happen any more. That’s a sign the oil is in distress.
Also there is a very limited, very small detergent package used for that oil. It’s also almost always a single grade oil. So I think it’s not practical to leave an oil formulated for break in longer than absolutely necessary to get break in done and then get rid of it.
If I am doing an engine in the car once the break in is done I drive the car through a good heat cycle, maybe 20 minutes under varying load and then take it out.
The issue is how the bored are finished. If the cylinders are honed using “modern” techniques the rings may take longer than just a cam break in cycle.
The end user should recognize that and ask the engine builder how long the rings should take to come in.
If he says 500 miles get your parts and find a better shop.
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