Partial Rebuild break in?

[Guest rockabillybassman]

I've just rebuilt my P26 with new rings, bearings, valves etc. I'm just about ready to drop it back in the car, but I'm a bit confused (easily done) about oil. I read a lot of posts where people use single weight oils, and a lot of others where people use multis. Bearing in mind there is next to no filtration on these motors, my initial idea is to run 30W no detergent and change it at 100 miles, then replace with the same with an added supplement (OES). I've been reading how many muliweights have had their zinc (ZDDP) content reduced to meet eco standards, but the zinc is what protects flat tappet cams from wear. Modern engines with hydraulic cam followers dont need this feature.

So, what are peoples thoughts on this? Should I go with non-detergent oil so that particles turn to sludge and sit in the bottom of the pan, or should I go a detergent multiweight for a cleaner engine and run the risk of particles getting dragged into the bearings? The bypass filter is about as good as having no filter at all!

[Don Coatney]

Tim;

When I had lunch with Don Gaines last week we discussed this. Guess we need to prompt Don Gaines to jump in on this. I do not have his e-mail address on my traveling laptop.

Don Coatney

[greg g]

I have used 15w 40 in my rebuilt P26 engine for 2 years. My machine shop guy told me to put a couple heat cycles in it running it at high idle 1200 to 1500 rpm up to operating temp, let it cool down and do it again.retorque the head, then he said to drive it like I stole it, change the oil and filter at 1000 miles. So that's what I did. Put new 15w 40 I got from Tractor Supply Company. Traveler Premium in a 2 gallon container. It is approved by MACk Trucks Diesel applications.

[Normspeed]

There are as many theories as there are drivers. I took some advice from Jon Robinson on the DeSoto forum. Like Greg, I began with a couple of warmup/cooldown cycles at 1500 rpm and then I retorqued the head bolts, but my initial oil was Castrol GTX 5W 20. I ran that for 500 easy miles, then I changed the oil and filter and ran 2,000 miles with Castrol GTX 10W 40. Then one more oil and filter change, this time using Shell Rotella T 15W40. It has the tappet additive. Jon says the heavier grade oil is good for the long stroke of the flatties. I believe him, he drives his DeSoto coupe all over the country!

[Young Ed]

The local flathead guru says to run 200 miles on straight 30 nondetergent to start and then go to 10w40 or whatever you plan to use. To him a mopar flathead is childs play. He does stuff way older then that all time. Also has the contract for the antique packard limo service in town.

Ed

[Guest rockabillybassman]

Dodgepu1946: that's sort of roughly what I figured. The nondetergent oil will give any metal particles that come off the rings or bearings a chance to sit in the pan to become sludge whereas the detergent will keep it circulating. I read somewhere that an old speaker magnet stuck to the side of the oilpan will help collect those particles too. I have no faith whatsoever in the factory bypass filter, so I want to treat the engine as if it does'nt exist.

[Lou Earle]

George Asche had me run 30 weight non detergent for 100 miles then drain.

then regular 30 detergent until broken in.

How do you know broken in? watch your fan after heating up- turn engine off if it does not kick back it is NOT broken in. When it kicks back ( usually around 1200 miles) it is broken in. Then run detergent-your choice.

As to the by pass. It does an adequate job and in fact large truck have a bypass filter in addition to the regular one. Why? they run a very fine filter in them to catch the smallest particles. Why because it is slower than regular full flow filter, The Amsoil site has some info on this.

As a practical matter the by pass works well if you drive and the oil pressure e is over 30? or some level.

George Asche has a 51 or 52 he has driven almost 300 thous using by pass filter and synthetic oil - he says he is going to rebuild it soon- smoke a little now!!!

In A model fords we make our own bearings and those engines are lasting 100 thous now before burn any oil. And with NO filter the vast majority run multi weight and high detergent oil .

If your really concerned about particles in the oil change it every 1000 miles like the book says.

On my 48 Plymouth I had in 57 yes 57 it had over 100 thous when I got it - (my mother drove it on dirt roads and a public health nurse in Va.) It Burne a quart every 3 to 400 miles- but I note the new 52 wagon Tom McCall tested in 52 burned a quart every 330 when he drove it over 60. I used used motor oil in that car and my later52 and later 54 for untold miles and years. not good or bad just did. No problems except with my slender pocketbook - that was why used oil!!I ragged the hell out of that 48 - Did you know you can go to 50 in second gear?? Never any engien problems in any - but Did you know u could get a used trans or rear end for 10 bucks then?

When all the dust settles it is quite simple-- these engines will last forever if treated and serviced properly with the better oils of today even with the by pass system. And remember the by pass system was an option early on!!! but if worried convert to full flow or change oil a lot.

Lou