(also posted in Northstar forum)

OK, I've read through all the oil posts - but forgot which one mentioned GM Engine oil supplement vs engine oil supplement - Assembly lube.

Anyway I went to my local dealer and bought 3 pints of "E.O.S. Assembly Lubricant", part # 1052367. Gr 8.800.

This stuff has a statement on the back": GM recommends E.O.S. Assembly Lubricant only for the specific purposes listed above. GM Does not recommend the use of this or any product as an additive to engine oil".

The specific purpose listed above is basically where to put it when assembling an engine.

So.... is this a GM disclaimer to keep the corporate lawyers and EPA nazis happy or should I really not be using this stuff in my Fleetwood or ElDorado (or my 68 DeVille Conv for that matter)???

How does STP oil treatment contrast with GM EOS. I remember the STP stuff to be almost molasses like in consistence, but it helps keep my old 472 running for a long time until i rebuilt it. :stirpot:

The word I got from an engine developer / builder with ~20 years of experience (and a rat rod Seville at his shop) was exactly what you proposed. Legalese, and no more. Because of all the ZDP in EOS, it tends to destroy catalytic convertors, hence the warning. I asked him about using EOS; he suggested putting in a pint with every 5 quarts or so, every oil change.

In my mind, it is cheap insurance against the flat tappet monster. I have read at least one published article, maybe more (no references I recall this morning) that suggest the same thing.

Not sure I would put it in something with a cat, but there you go!

Also, do some digging here http://theoildrop.server101.com/forums/postlist.php?Cat=0&Board=UBB5

Lots of good tech info for the looking...search ZDDP or EOS, you'll get lots of info.

Andy Granatelli and STP paid the largest consumer fraud fine in history at the time, $660,000 because they were unable to prove that STP did ANYTHING beneficial for an automobile.

OK, so i guess, STP is out and GM EOS is in. But the STP did help cushion the worn main and rod bearings in my tired 472 for 7 years :thumbsup:

like my dad always said to me just oil in the motor plan a simple, he belived addittives gummed up the block and oil passages making oil flow reduced. So ive aways made sure i just keep clean oil in my motors. just my 2 cents

Did anyone ever try to explain to the geniuses at EPA that if a car doesn't BURN oil, then how can ZDP / ZDDP get burned and sent through a CAT ??? what are those fools at the EPA smoking anyway :want:

I was at the engine rebuilders yesterday, and there was a guy that SWORE up and down that PROLONG was the ticket to all issues. He had his Ford there that had 268k on a rebuild, and he said that he has used PROLONG since the second oil change, just add it a quart in a regular oil change.

I personally havent used it. I have used the Lucas Extended Life on all my cars in the past, and I can stand by that one. Thanks-Chris

After being involved with cars for over 30 years I have to ask. Why do people ask engine rebuilders questions about stuff and take their answers as gospel???? Engine rebuilders might see engine innards all week long but they don't see general repair work as part of their job. Most of the rebuilders I've seen breather too much CRC vapor. Same deal as news people asking rock stars about world events in the 60s.
As far as cat converters they can be ruined by the wrong type of RTV silicone. It doesn't take much to kill a cat. The wrong kind of additive can kill one just by gassing out.
There are pages and pages of oil additive banter on the internet. Some of it is pure BS and much of it is posted by junk science subscribers. Some of it might be useful but you need a good BS filter. Oil gets contaminated by unburned fuel and spent fuel byproducts. Older carbureted cars wear out oil additives much faster than modern fuel injecter autos. Proper oil change intervals are plenty good enough to keep things going. Another pitfall is people insisting on using 10W30 in 70s cars. Stick with 10W40 and save your money on magic additive. Modern detergent oil is really good stuff. Keep the money for when things break.

Another pitfall is people insisting on using 10W30 in 70s cars. Stick with 10W40 and save your money on magic additive. Modern detergent oil is really good stuff. Keep the money for when things break.

Hey Ape Man, could you fill me in on the 10w30 vs. 10w40 for 70's cars? Thanks.

Simple. 10W-40 works fine, 10W-30 might not.

10w-30 is too thin for the engines of the day.

10w-30 is too thin for the engines of the day.

It sure is. It is however listed as being OK for use in many owner's manuals back then. The stuff lands up going bye bye somewhere. A good Cadillac made engine with no leaks usually needs no topping off between oil changes. Not so with 10W-30.

Since my engine has such low mileage (5K), I'm gonna keep using 10w30 and gradually work my way up to 10w40 over the next few changes.

whilst you are thinking about it what are your thoughts on 20w50

20w-50 works ok for that engine which is on the downward slope of it's useful life.

mine has less than 500 miles on a newly rebuilt engine, guess I will stick with 10w40. THanks!

Another pitfall is people insisting on using 10W30 in 70s cars. Stick with 10W40 and save your money on magic additive. Modern detergent oil is really good stuff.
On the contrary, modern SM grade conventional passenger car oils are a disaster waiting to happen in flat tappet engines, and 10w-40 is one of the worst. :Poke:
The ZDDP levels in regular passenger car motor oils have been drastically reduced in recent years, (from around 1200 ppm to 800 ppm today). This has resulted in rash of cam/lifter failures in flat tappet motors. Furthermore, they are made from crappy group I base oils.

On the other hand, heavy-duty 15w-40 diesel motor oils such as: Shell Rotella, Mobil Delvac, etc. still have decent levels of ZDDP, plus they are made from superior group II base oils and have excellent detergents.

See link:

http://www.motorcycleinfo.calsci.com/Oils1.html

On the contrary, modern SM grade conventional passenger car oils are a disaster waiting to happen in flat tappet engines, and 10w-40 is one of the worst. :Poke:
The ZDDP levels in regular passenger car motor oils have been drastically reduced in recent years, (from around 1200 ppm to 800 ppm today). This has resulted in rash of cam/lifter failures in flat tappet motors. Furthermore, they are made from crappy group I base oils.

On the other hand, heavy-duty 15w-40 diesel motor oils such as: Shell Rotella, Mobil Delvac, etc. still have decent levels of ZDDP, plus they are made from superior group II base oils and have excellent detergents.

See link:

http://www.motorcycleinfo.calsci.com/Oils1.html


Sorry but this isn't the high performance chevy b-board. The engines in question use billet camshafts with very light valvespring pressure. They do not grind tappets flat like lesser brands. What they do is wear out main bearings due to long stroke and large reciprocating mass. Most dead Cadillac engines of this vintage died from spun out bearings and had OK valvetrains. Nice try.

Sorry but this isn't the high performance chevy b-board. The engines in question use billet camshafts with very light valvespring pressure. They do not grind tappets flat like lesser brands. What they do is wear out main bearings due to long stroke and large reciprocating mass. Most dead Cadillac engines of this vintage died from spun out bearings and had OK valvetrains. Nice try.
It doesn't matter. I was merely pointing out the potential problems associated with the depleted levels of ZDDP in SM grade conventional motor oils.
ZDDP is the main anti-wear additive and the higher levels in diesel motor oils will help with any kind of engine wear, along with other benefits. Naturally, all else being equal, flat tappets lifters, which are under high pressure will usually be the first to fail.

The fact that you're recommending 10w-40 proves you don't know what you're talking about, again.. :Poke:

It doesn't matter. I was merely pointing out the potential problems associated with the depleted levels of ZDDP in SM grade conventional motor oils.
ZDDP is the main anti-wear additive and the higher levels in diesel motor oils will help with any kind of engine wear, along with other benefits. Naturally, all else being equal, flat tappets lifters, which are under high pressure will usually be the first to fail.

The fact that you're recommending 10w-40 proves you don't know what you're talking about, again.. :Poke:

Anybody can read sales literature. Real experience takes years. Come back and see me in about 20. Good luck.

Gm has reinstated this EOS and the new number is 88862586.

GMpartsdirect.com has it for $11ish... And I am sure an arm and a leg for shipping....

I too believe in 15/40 oil designed for a diesel application to be used in older gas engines because of the anti wear additives. For about 5 years I owned both an 84 Eldo 4100 and a 81 300CD Mercedes. I used this oil in both. On the Cad it lessened the front main bearing knock common on this car in the hotter summers. Prior to that I had used EOS frequently. Zinc is the anti wear additive that has been lowered in quantity in newer oils. EOS and 15/40 diesel oils still have that in a higher amount.

I just use CI-4/CI-4 Plus oil.... Works for me....

I guess the advantage of having EOS is you can run your favorite 0W30 or 5W30 oil and toss in some EOS to up the ZDDP to boost the antiwear properties... According to the last mag article I saw, the new CJ spec diesel oils STILL are better than any of the car oils that have ever been for levels of ZDDP.