How many miles does it take to break in a new engine? 302/4bl mild cam/ bored .40 over.
I've put around 700 miles on it and I'm still getting a small amount of blowby on both sides of the engine warming up, but after driving it for a while I will only get it on the PCV side. I think I may have put the wrong type of break in oil, I just the 10/40, was I suppose to use a different type of oil?
Thanks

 

Something with a lot of ZDDP additive would have been ideal, but you can't change that now. 10W-40 is fine.

Full engine break-in takes a good 10k miles or so. During this period you want to be running conventional (non-synthetic) oil only, with more frequent oil changes. Full cam break-in takes about 200 miles, during which time you want to be varying the rpm's as much as possibly and avoiding the freeway.

But if you want to seat the rings, do a couple 3/4 throttle runs down a nice straight road. I've even talked to some old school types that do burnouts to seat the rings

 

The first 200-300 were mixed with city and hwy and various speeds. A friend at work told me that I should drive long distance with hillie roads and get on it going up hill to help seat the rings, is this good ? , I just did that over the weekend, and ran it hard at some points.

 

Did you change the oil yet? You should change the oil after 500 miles to get all of the added break in lubes out and everything from the parts wearing in.

 

I've talked to the folks at AMSOIL about this both on the phone and a few reps at the car shows. They have all said to run conventional oil for the first 4000 to 5000 miles for a good breakin. After that switching over to a synthetic is suggested. With 700 miles on it not you should be doing your secondoil change. If you haven't then you should change the oil soon. At 1000 miles change it again still using a conventional oil. Do this every 1000 until you get at least 4000 to 5000 miles on it. Then you can switch over to a good synthetic.

 

With my 67, I had the engine rebuilt 3 years ago. I made sure to change the oil every 300 miles for the first 1200. I would like to think it made a difference.

I have never seen someone say 10k for an engine break in before in my life time. You should get all the loose ends taken care of at about 2500-3000k.

+1 on cam break-in 200 miles, again play with the rpms as much as possible!!!

 

I did change it about 400-500 miles, butwith 10/40 Penz,is itok or should I used a different grade of oil? some as 5-30 or even 10-30?
Thanks

 

I ran mine for 500 miles and changed the oil, then I changed at 3000 miles. I use Delo 400 oil 10-40. I think the Delo 400 is a better oil than Penz-oil.

 

my whole family has always used pennzoil and never had any oil related trouble with motors and 10w40 is perfect. now because everyone screwed up their formula's due to emissions crap its recommended you use rotella 15w40 for your initial breaking in, but after that regular oil should be fine.

for the record i do mine at 200 miles give or take, then again when the motor is up to 1k miles. after that its every 3k. cast iron rings will be seated in 1k miles, and the moly coated rings most of us use these days should be seated better by the 3k (4k total on motor) oil change.

 

It takes longer than most people realize for all of an engine's friction surfaces to completely wear into eachother. Most of the break-in process isdone by 5k miles, butit cantake up to 10k to complete the process. I wouldn't worry about thrashing it around after the 5k mark, but I would recommend holding off on synthetic until 10-12k to allow everything to completely break in.

Penzoil is crap:-| Lots of sulfur content, not a lot of anti-sludge additives. The sulfur combines with exhaust gases to form sulfuric acid, which is just wonderful for engine components long-term.

As far as ability to withstand abuse... One of my friends owns a dirt track car and runs pit crew for a couple others. He forgot to bring oil on one trip and was forced to buy Penzoil because that was the only oil dealer at the race. The engine ran really hot towards the end of the race and developed a lifter tap. When they pulled a valve cover, they found nothing but foam. Most of the oil had been aerated so badly that it had turned into a foamy mess. Needless to say, he doesn't use Penzoil in anything, ever. Neither do I.