break in oil
 

I just finished rebuilding my 4.0 in my 96 Cherokee, I've pretty much got everything back together under the hood (I had 270,000m and the throw out bearing went out, so I decided to rebuild everything) I usually use non-detergent oil for the break-in. At the parts store I saw some break in additives (Royal Purple for instance). I was wondering if anybody had any thoughts or insight on the subject of break-in oils?

No such animal as "break-in oil"........just use name brand 5W30 motor oil.

there are some things sold as break in oil, said to have more Zinc, etc in them. Supposed to "help" seat rings and keep cam wear down, etc.


From 95 FSM:
"Special break in oils are NOT recommended"

break in oil
 

the '95 book didn't take into account the zinc, etc the oil companies have taken out of the regular old oil we've came to know and love. I would suggest using a break in oil, and also an additive to keep from wiping out the cam. Take it for what it's worth. Good luck:thumbup:

There are all kinds of snake oil additives out there however, if you used a good assembly lube on all rotating parts during engine assembly, you should have no start-up wear issues. Let us know what brand of "break-in" oil you find. I still say there's no such animal.

Todays motor oils are far superior to those of 15 years ago.

Thanks for the responses, I checked on the Royal Purple web site and they make a break in oil and there thinking looks pretty sound:
http://www.royalpurple.com/breakin-oil.html
http://www.onedirt.com/news/new-prod...rom-comp-cams/

This site has some good info even though it's geared towards motorcycles:
http://motorcycleinfo.calsci.com/Oils1.html

Even though that motorcycle info is a touch dated its actually a very good read.

While I am not a fan of Royal Purple's products due to their corporate decisions. They used to concentrate on making high quality products for high performance situations. Now their emphasis has shifted to the mass marketing of their products.
Do you know the actual manufacturer of the Comp Cams product? Unless I did I would hesitate to use it. Comp Cams makes excellent camshafts...but they don't make oil....

Several of the other synthetic manufacturers make break-in products...
Here is Brad Penn's
http://www.bradpennracing.com/Produc...ak-In-Oil.aspx
Joe Gibb's Driven...
http://www.joegibbsracingoil.com/pro...kin/index.html

I believe that Valvoline has one also, but I can't find a link to it at the moment.
Edit... they do make one. They sell it under the Roush Performance brand. But the catalog there is giving me fits to link it here.

Im emailing them for the MSDS, but it looks like its made by "Endure Performance Lubricants"

when i had my motor built for my mustang the only thing that needed proper break in was the cam. my builder told me i dont have to worry about breakin in the motor and i should run the way the i planned on driving the car. motor has almost 25,000 miles and over 100 low 10 second nitrous passes on it now. it still makes the same power on the dyno as it did the day it was put in the car.

Update
 

I found a local parts store that would order the Break in oil I wanted (Royal Purple). I read a lot threads here on motor oils. All my vehicles are High Mileage and they run great, I've got in excess of 350,000 on my 460cid in my 79 F-250 4X4, My Jeeps all have well over 200,000. They all run smooth, start every day and are dependable. Except for my 2005 Class C Motor Home, I change the oil in my vehicles once a year. The MH is still under Warranty and I change it as the schedule dictates. I sent a email to Royal Purple and with there permission I'm posting thier response:

Good Morning Mr. Addington,

Break-in motor oils are relatively new to the market and came about because of the need for motor oils that still contained adequate anti-wear (ZDDP) to protect an engine’s valve train. As you are likely aware, recent API ratings for motor oils have further restricted the allowable Phosphorus content, and therefore ZDDP content, of motor oils due to emissions concerns. This anti-wear additive is vital to the life of flat-tappet camshafts and any other highly loaded sliding surfaces in an engine, such as your Jeep 4.0L. The purpose of a break-in oil is first, to protect the valve train, and second, to allow the new piston rings to seat quickly to freshly honed cylinder walls. Royal Purple Break-In Oil is just such a motor oil. It is basically a high quality 10W-30 with a high anti-wear additive content. It is not intended as an extended use oil and we recommend maximum use of 2,000 to 2,500 miles. The link below will take you to the Break-In Oil page of the Royal Purple website.

http://www.royalpurple.com/breakin-oil.html

I enjoyed the pictures you sent of your 4.0L. It is a beautiful engine and it would be great to have a bottle of RP Break-In Oil pictured with it. I did notice that a comment was made concerning use of a good assembly lube being all you need. That is partially correct in that you need very good lubrication on the cam and lifters at first start-up, and the assembly lube fills this role. However, once the engine oil is flowing to the valve train, the assembly lube is soon diluted/washed away. You will then need good anti-wear protection from the engine oil at the cam lobe/lifter interface. Please feel free to post the picture(s) you suggested and this email, if you like.


Best Regards,

Christopher Barker
Tech Services
Royal Purple, Inc.