I've been using Rotella T diesel oil for several years now per recommendations on this board. I went to change the oil today and realized I was out. So down to the parts store and they were out, too. Then I remembered this post on Hemmings a few months back and decided to hold off til next weekend til I asked here.

http://blog.hemmings.com/index.php/2007/12/07/hmx-countdown-to-ignition-t-minus/

This bottle of Rotella T was rated CJ-4, which is the latest (as of 2007) specification for diesel oils and follows the spark engine oil trend of low zinc content. Only diesel oils rated CI-4 or earlier (CH-4, CG-4, etc.) have the proper zinc content. As for spark engine oils, look for an API rating of SE or earlier (SD, SC, etc.) for the proper zinc content. Don’t do what I did and buy diesel oil expecting it to have enough zinc for your engine break-in.

So have they changed the formula? Do I need zinc in my old 361? (which has never been rebuilt to my knowledge.) Any better oil out there than Rotella T? Thanks.

I don't feel that it is nessessary in older flat tappet cam engines that are relatively stock with not very high valve spring rates.

Will this subject every get ironed out for the masses?

Get yourself some Delo 400 LE 15W40. NAPA's house brand 15W40 "diesel" oil, or Valvoline's 15W40 diesel oil is good. They are all CJ-4 with plenty of zinc (1300 plus ppm) for stock to mild builds. In fact, many of the racers run the 15W40 diesel oils. Plenty of zppd (zinc) for ya, at least 1300 ppm.

The synthetic diesel (also called heavy duty engine oil HDEO) has more zinc than the dino oils.

Shell Rotella T 15W40 has just under 1200 ppm zinc. Shell Rotella T 5W40 synthetic has over 1300 ppm zinc.

Do a search. This subject has been covered real well.

Can you break in a new cam with 15w40?

When breaking in a new cam I always use EOS or whatever high-zinc cam break-in lube (Comp sells some, for example) teh cam manufacturer calls for. If I was running a flat-tappet cam with a lot of spring pressure, I'd want to break it in with weaker springs then swap in the stiff ones. A cam with wiped lobes is an expensive pain in the butt compared to using a little caution; OK, call it paranoia!

Here's a delo 400 LE oil analysis, 1300 PPM zinc.

http://www.ford-trucks.com/forums/606026-virgin-delo-400-analysis.html

I think the zinc is more important for new flat tappet break-ins than for older engines. A 20 to 40 year old engine that's been well-maintained has an established wear pattern on the cam and lifters and is probably safe with reduced zinc levels.

There is a world of difference between the stock cam lobes and springs of the flat-tappet era and the ultra-high acceleration lobes and big springs of today. Even the 30-year-old "chevy lobes" found on many high performance cams of the 70s were really mild in comparison.
So you have to be really careful breaking in a new high intensity cam.

One thing that always makes me wonder, it is easy to say use weaker springs but where do you get weaker springs for a 0.545" lift camshaft?

R.

I agree. I use Delo 15w40 in everything I have. Not only that, I get a discount from my dad's construction business if I go to the diesil fuel stations.

One of my 318s now has 6000 miles since rebuild with a Comp XE268 cam. Can I discontinue use of the Comp break in lube and just use the oil? If I could save $13 dollars an oil change and still be safe?

Dont mean to hijack, but maybe it could help others out if they search the same thing in the future.

i've always thought you used 30w on the 1st start up and 20min break in.