Hi guys
Got my 337 motor back from the rebuilders last week and was wondering what kind of oil to use. He recommended using an oil additive from GM to help lubricate the lifters. I searched the forums for this question and didn't come up with much. I am pretty sure this topic has been discussed before. Can I use synthetic motor oil in a flathead? What would be the correct weight to use? Thanks Keith

 

It's GM EOS, Engine Oil Supplement, and highly recommended if breaking in a new cam. You risk severe and fatal damage to the new cam and lifters with out ZDDP, zinc compound that prevents wear and is the main ingredient in EOS. Any GM dealer should have it.

Did you do an Advanced Search on this forum (only)? Search on "EOS ZDDP" it will pull up the exact thread you are looking for.

 

I did a internet search on this subject last week. What I found was very confusing. They also discussed this subject a few weeks ago on the Ford Barn, do a search of that forum, Fordbarn Early V8 Discussion Forum. It seemed that the consensus was divided 50/50. Some guys said the new oil will wreak havoc on your lifters other said no, it won't do anything bad. Some said to use oil designated for diesel engines because it don't have to meet the strict government or industry standards as oil made for gas engine. I also read that GM doesn't make the break in product anymore.

I suggest you do some more searching and try to figure it out. I would hate to see you harm you nice rebuilt engine.

 

Thanks guys ... i will do more research
Keith

 

Good luck Keith, when I did my minor amount of surfing on the subject I got conflicting opinions. I got a head ache reading and had to quite.

Good to hear the engine is back and you got the throw out bearing problem fixed. Get that beast on the road!

 

I know some NAPA stores now carry the additive but I cannot remember what it is called. Since they are all independents I am sure all of them won't have it but maybe a local one near you will.

 

The reduction in ZDDP the Zink additive has been going on for several years now. Most oil's including the synthetics and diesel are down to 0.
The zink in the oil was useful in tight clearence areas, cam bearings, flat tappet cams and rod bearings, mostly found in older engines and/or racing engines.
The reason zink was removed was that it fouled the catilitic converters so use of zink in our engines is no problem.
I intend on running straight 30w with a zink additive.
Check with Lucas, I think they make an additive now.

EDIT: This was from a few yrs ago.
http://www.hotrod.com/techarticles/e...ech/index.html

 

If you can find someone selling the old-spec CG or CH diesel oil, that is likely the best bet. A lot of places still have it for off-road equipment (heavy machinery like bulldozers, etc). As far as I know, flatheads are in a low risk category once broken in, because they have lower valve spring pressures. But any flat-tappet engine with a new cam and/or new lifters really needs some additives during the first couple hours' break-in.

 

Thanks guys. I always know where to turn to for some good solid advice.
Buy the way I added some new pics in my gallery. Thanks Keith

 

The info in this thread is spot on. Yes the, newest diesel oil doesn't have the extra zinc like it use to.
The GM cam break in is good stuff(somebody mentioned GM quit producing it), the cam makers have started selling similar products.
For the Zinc needed, alot of people have gone to a OFF-ROAD Oil(meaning it has no requirments to meet for emissions) these are typically racing oils. One of the best is:Penn Grade 1 Racing Oil This was formally Kendal I believe. Type in Brad Penn on google and there are many different places to buy. I hope this sheds some light on yet another option

 

Thanks for the Penn Oil Ref.
I had a complete brain lock on that. Maybe I need to open up the skull and lube the rocks.

 

one thing to keep in mind is that a flathead does not have to have nearly as high spring pressures as an overhead valve engine so the zinc additive is not nearly as critical as it would be in an overhead valve engine. I have been using 15w40 rotella in my engine for about three years now and my truck gets worked pretty hard. I have not had any issues sofar. As far as synthetics go most synthetic oil companys say not to use synthetic oil for break in.

 

Keith - looked at the gallery pics - I love that chassis saver paint, but I'll tell you, any "friend" who'll spray it on for you, is truly a friend, indeed!! I'm STILL cleaning it off my glasses after a month, and I didn't even spray it (although I'm getting ready to spray some).

Looking good!

R

 

Just a tip, make sure you prelube the engine before you start it or turn it over. As a teenager I destroyed a fresh rebuild when someone told me they had already prelubed it when they hadn't done anything more than fill the oil pan.
Our local napa store actually rents a rig that is more or less a pressurized oil can that you thread a hose from into the oil galley and blow in oil under pressure. It'll save you a very costly second rebuild (I speak from experience here - don't be a dummy like me).
Best of Luck.
AJ

 

Thanks for the info and comments guys!!
Keith