The other day on another message board I read that though GM is no longer offering EOS, AC Delco is offering it under the AC Delco name. I promptly went to the AC Delco site and sure enough there it was. The AC Delco site did stipulate their EOS was not be used as an oil supplement. So with the availability of EOS through AC Delco is there any need to buy up all of the GM EOS a person can find?

Thanks,
Mudbone64

 

I too have wondered if GM EOS was going to be similar to the days when the old R-12 A/C refrigerant was "going away" and everyone went nuts trying to hoard it.

Lately there has been a lot of oil related articles in auto mags addressing the lack of zinc and the failure rate of flat tappet cams.

COMP Cams promotes their own additive---similar to EOS---that they feel should be added at every oil change. I believe it is around $12--a little pricey, but good insurance on cars that see limited street duty and long periods of storage.

 

GM EOS specifically states that it is to be used as a coating when assembling parts and should not be added to the oil as an oil supplement. I bought up a bunch I found at a local dealer. The first dealer I went to say they didn't have any because they hadn't used any in a couple of years. He found another local dealer that had a good amount (no doubt ordered by mistake). My impression is that GM discontinued it for lack of demand as new engine do no need this when being assembled. It doesn't make a lot of sense for Delco to offer the same thing in a different package if the demand is low. Quite possibly the formula was changed.

 

It would be nice to be able to verify if there is any difference between the GM and AC Delco formulas.

 

Contact them through the AC-Delco website and ask if they're going to continue to offer it or if they're also discontinuing it.

 

I sent them an e-mail. If I get a response I'll post it here.

 

I asked:

I had heard GM was discontinuing "EOS" and then I heard that AC Delco
was
offering it now. I checked the AC Delco web-site and was happy to see
AC
Delco now marketing it. My questions are: Is it the same formulation
as
the GM EOS and does AC Delco plan to continue to market it?

Any help you can give me is greatly appreciated.

Thanks

They said:

We appreciate your e-mail regarding E.O.S. Assembly Lubricant. The
product
is available as ACDelco part # 10-106 or GM part # 12371532.

To best assist you with your inquiry, we recommend that you visit your
local ACDelco Service Center. The trained professionals are equipped
with
the latest technology and information and would be in the best position
to
assist you with your inquiry.

Please know that retailers, unfortunately, often carry only a selection
of
ACDelco products and are unable to order parts they don't stock. For
the
best assistance obtaining E.O.S. Assembly Lubricant, we recommend an
ACDelco Service Center or GM Dealer. If they do not have the product
in
stock, they will often happily order it in for you.

To find the nearest ACDelco Service Center in your area, please visit
our
web site (www.acdelco.com) and enter your zip code under the
appropriate
locator.
To locate a GM Dealer in your area, please visit www.gmgoodwrench.com
and
look for 'Find your GM Dealer' at the right of the screen.

Please note: When you contact us via email you are contacting the
ACDelco
Internet Support Team. We can assist with general ACDelco inquires;
however, we are not certified technicians. For this reason we ask you
to
speak with the technicians at your ACDelco Service Center

If you need assistance in the future, please visit our website again.

Thank you for your interest in ACDelco.
ACDelco Customer Assistance

So still no clear-cut answer.

 

Can you enlighten those not in the know? What does EOS stand for? I see from the previous threads it's some sort engine assembly lubricant? Where is it used when assembling the engine?

I've never put together an engine before, so maybe that's why I'm unfamiliar with it.

 

EOS is an acronym for Engine Oil Supplement . Its an oil additive rich in ZDDP that was supplied to shortblocks and crate engines that were sold over the counter. It is to be used as a break in additive only and not in a regular oil change.

 

Oh, ok....I see. So after the engine is put together, this EOS is used in conjunction with say 10w-30 when filling the engine with oil for the first time. When the break-in period is complete, just use regular 10w-30 by itself after that(10w-30 was just used as an example).

Or am I still not getting it...

 

yes except you need to use delo or shell rotella diseal oil as it still has the proper formulation for flat tappet cams/lifters.

 

It's not my purpose to incite another oil debate, but I think the "good stuff" that protects flat tappet camshafts was removed from the Delo and Rotella oils and the beginning of 2007 thus the need for an additive. I also believe the Delo and Rotella oils are high in detergent which will render a zinc additive useless in protecting flat tappet camshafts as well. Again, I'm no technical authority on this subject, I've just read enough to be very nervous.

Mudbone64

 

The new API rated diesel oil CJ-4 has a reduced amount of phosphorus( anti wear component of ZDDP) than CI-4 . However it is quite adequate for vintage flat tappet engines and still has the richest ZDDP package than all the SM rated oils.

 

What about the GM "lifter prelube" additive? I thought that was to do the same thing as the EOS, and was intended to be an oil additive. I think it is recommended to preserve flat tappet cams.

Never quite understood how an "engine oil supplement" was "not to be used as an oil additive."

 

Redline 40W racing oil has approximately 2700 PPM zinc and 2500 PPM phosphoros. I believe these amounts exceed by a wide margin what even diesel oils contain. So, for the truly paranoid (which often includes me), if you can stand the cost, this represents another option. One note, though, this is a non-detergent oil.

Jim