Ok, I have my almost new (about 300 miles on her so far) 350 crate engine humming along nicely so far. I broke in the cam, changed oil and after 300 miles just for kicks, changed the oil again (yeah, I'm paranoid). I was wondering if there were any recommendations for what mileage needs to be put on a new engine before switching to a full synthetic motor oil? I could have sworn that I read that you should put at least 3000 miles on it to allow everything to be completely broken in before switching to synthetic, but I can't seem to find that reference anywhere. I can't remember where I read that or I wouldn't be bothering you guys.

Everyone happy with synthetic oil that's using it on their flat-tappet cam engines? I am planning on using Mobil 1 since it is easily available locally.
Thanks for any insights.
Brad

 

I usually wait until the first full mile oil change, so about 4-5K. Sometimes the second if I'm lazy or something.
If I were to run a flat tappet cam I wouldn't do Mobil 1 (and if I weren't to use Amsoil) I'd look to the synthetic Delvac or Rotella lines as they have better levels of ZDDP or equiv. (like the Amsoil).

 

I waited about 600 miles, then switched to Mobil1, on my flat tappet cam.

Red Devil should be swaying a pendulum, telling you to use Amsoil I hear that's really good stuff, if you can find it.

 

What's wrong with using Mobil 1 on a flat-tappet cammed engine?

 

Mr. Devil did not fully explain the situation, since you could/should research the lubricants that you intend to use. If you did, you might find that MOST automotive engine oils are no longer including the extreme pressure lubricant additives once used to protect the high load/sliding members like lifters against a camshaft lobes. The reasons are mostly environmental. The major oil companies argue that most modern engines have roller lifters, and therefore don't require the extra protection. However, lubricants designed for truck and diesel engines still include the additives. Whereas the typical variety of Mobil 1 may no longer have the zinc, barium, and other anti-wear additives, Mobil Delvac Synthetic (and Delvac mineral oil) still does. Many Amsoil products also contain the additives, whether for aoutomotive or truck/diesel engines.

Pay attention to the boy, since he's got a pretty good clue about that which he writes. Not only are some synthetics NOT the best choice for breaking in a flat tappet cammed engine, but it may no longer be a good choice for even running that engine AFTER break in. That doesn't apply only to PAO synthetics, but ALL automotive engine oils. Read and/or research carefully what is and isn't in that "same oil" you've always used without problems, since things are changing.

As for the time to switch to a synthetic, that may depend as much on the rings as mileage. Since the cam is evidently already run in, the rings are the next critical item to break in and seal.

 

Hmmm... this may cause a re-think on the oil plans. I remember someone stating that one of the major car magazines had written an article on this very issue (the decrease in certain additives in modern oil). Does anyone remember which magazine published this?

 

The one I recall seeing recently on the Board was a Pontiac magazine.

Like Vader said, truck/diesel oils still have the extreme pressure additives in them. As long as the oil is also "S" rated (such as "SL" or "SM"), it will be fine for a gasoline engine and will protect the flat tappets. However, it most likely won't be GF-4 rated, as that is the emissions stuff to which Vader referred.

Personally, I use AMSOIL 10W-30 in engines that have roller lifters, and AMSOIL Series 3000 HDD 5W-30 in engines with flat tappet lifters.

 

Mr. 5-7,

Just to be technically correct (this IS a tech forum) what EP additives are still used in the HDD lubricant? I understand that zinc and barium used to be common additives, and sometimes phosphorous, lithium, and even molybdenum are/were used.

AFAIK, the "emissions" question is as much for disposal after draining as it is for potential airborne emissions during use. Does that agree with your information?

 

Zinc & phosphorous are what I understand, but exact formulation isn't shared. The other thing I like about the HDD is the high TBN, since those vehicles happen to be occasional-use/long storage.

As to GF-4:

3. BENCH TEST REQUIREMENTS
3.a Catalyst Compatibility
Phosphorus Content, ASTM D 4951 --- 0.08% (mass) maximum
Sulfur Content, ASTM D 4951 or D 2622
SAE 0W and 5W multigrades --------- 0.5% (mass) maximum
SAE 10W multigrades ---------------- 0.7% (mass) maximum
3.b Wear
Phosphorus Content, ASTM D 4951 --- 0.06% (mass) minimum

Pretty tight requirement for phosphorus.

 

so here is a question then. on my honda it has the stock OHC setup with a flat nubbin riding on the cam lobe. would mobil 1 be bad juju in this case also


as a side note about spring pressure they are light enough I can open most all valves by hand without using any tools unlike most the springs used on your cars