Couldn't agree more. Most of the time someone who has been doing the same thing for decades has fallen into a routine. They become mentally inflexible and maybe even lazy. It's human nature I'm no different. So just because it works for them and has for 50 years doesn't mean it's the best or only way it's may be just their way. If they insist that their way is the only way I'm immediately wary of that opinion. Very few absolutes in this world, there are many ways to skin a cat.

 

I'm curious about this test. Which one (SAE) is it?

Decades ago I ran the IIID test in the lubricants division of a major oil company.

 

Most every statement above is patently false. I'll challenge the following notions:

"Zinc does NOT build up a coating on parts like some sort of plating process"

"The thinking that more zinc (than what's in today's offerings) provides more wear protection is only FOLKLORE,.."

"Oil film strength testing is the ONLY way to determine an oil’s wear protection capability,.."


It's time to go molecular. It's time to hear from real scientists, real chemists, and real physicists.

From here:

http://home.physics.wisc.edu/gilbert...cations/90.PDF

...is this:

"Currently, the most important antiwear and
antioxidant additive that is added to engine oils is a class
of molecules called zinc dialkyl dithiophosphates
(ZDDPs) [14]. Antiwear films generated from ZDDPs
are known to protect rubbing surfaces in engines, acting
as sacrificial films when being rubbed that are constantly
regenerated in a rubbing environment [15]. Studies have
shown that the breakdown products of ZDDPs, and not
the ZDDPs itself, provides the antiwear protection
needed to lubricate sliding steel surfaces within a simulated
and actual engine environment [16,17]. Several
studies show that ZDDPs decomposes upon rubbing to
form a protective film (tribofilm or antiwear film),
however thermal decomposition has also been the
accepted major mechanism of the antiwear film formation
[18–20]. It is well known that these films are comprised
of an amorphous polyphosphate glass structure."

From here:

http://www.pcs-instruments.com/pdf/e...rch_Papers.pdf (see pg 8)

...is this:

"The film formation behaviour of lubricating oils containing zinc dialkyldithiophosphate (ZDDP) additives has been studied in rolling, concentrated contacts using ultra-thin-film interferometry. It has been shown that ZDDPP-containing oils form chemical films which are
additional to the elastohydrodynamic (EHD) films produced by the base oil. ZDDP film formation occurs at elevated temperatures and begins in the range of 130°C to 170°C, depending upon the base oil type. The thickness of the films increases with temperature and test
time. The ZDDP films formed are typically 5 to 25nm thick and appear to be solid-like surface coatings."

From here:

https://www.stle.org/assets/document...ature_5-05.pdf

...is this:

"ZDDP forms a protective film—a glass—on the
surface of engine components. This zincphosphate
glass, which is rich in zinc at the
surface and then becomes higher in iron as
it nears the metal’s surface, becomes about
10 nanometers thick and somehow self-regulates
to stay at that thickness."

From here:

http://uhv.cheme.cmu.edu/pubs/SurfChemTrib.130.pdf
(starting with pg 10)

is this,..

"Zinc Dialkyldithiophosphate. There are few lubricant additives that have received as much attention in the literature as zinc dialkyldithiophosphate (“ZnDTP”, “ZDTP”, “ZDDP” or “ZDP”). Originally
added to lubricating oil as an antioxidant[25], it was rapidly discovered that it also functioned as a highly effective antiwear and extreme-pressure additive, and is an essential ingredient in the vast majority of current lubricant formulations.

...In other words, the (ZDDP) film is intergrown with the oxide on the steel, which presumably also enhances mechanical stability[34]. The mechanism also shows that the glass can function as a digestion agent for iron oxides, which are abrasive and therefore enhance wear."

From here:

http://www.apmaths.uwo.ca/~mmuser/Papers/TL05.pdf

Is this:

"Seventy years after their development, zinc di-
alkyldithiophosphates (ZDDPs) remain key anti-wear
(AW) additives in commercial lubricants used in auto-
motive applications [1,2]. This is particularly remark-
able considering that significant efforts have been made
over the last decade to replace ZDDP in engine oils."

Do you think any of the above scientists are wrong? Do you think they're trying to sell us something?

 

Excellent DOCUMENTATION to the testimony of the importance of ZDDP in the oil you use in a flat tappet cammed engine! Thank-You!

 

Why are you running such a thick oil? 15W oil does not provide good protection at cold temperatures, it is way too thick. Unless you're racing your car in Sahara I see no need for 50 at operating temperature.

Castrols description of 20W-50 from their website:

"SAE Viscosity Grade Motor Oil: 20W-50
Temperature Conditions: Above 20° F
Description: Provides maximum protection for high-performance, high-RPM racing engines. Excellent choice for high temperature and heavy loads such as driving in the desert or towing a trailer at high speeds for long periods of time."

I agree with your statement regarding zddp, just don't understand the need for such a heavy oil with bad flow/lubrication properties unless you're driving in the above mentioned conditions. I know you're not using Castrol, just giving you an example.

Synthetic oils were not widely available and in use when your 1978 owners manual was written. Synthetic oils have a higher base oil viscosity allowing you to run a lower grade oil to reduce start-up wear while maintaining film thickness at higher temps.

Amsoil Z-ROD 10W-30 synthetic, straight from their website:

"AMSOIL Z-ROD Synthetic Motor Oil is recommended for older or modified engines requiring either 10W-30 or 20W-50 motor oil."

Car Craft comparison:

http://www.carcraft.com/techarticles...ventional_oil/

"But claims and talk are cheap, so Car Craft had Westech Performance run some of the new Mobil 1 0W-30 in Ford's prototype 392 small-block stroker crate engine. The Mobil 1 was compared to the generic (and recommended for this engine) 20W-50 factory-fill conventional oil, as well as 10W-30 conventional oil. All tests began with the oil temperature stabilized at 210 degrees F. The engine ran from 3,300-6,200 rpm, and several runs were made for each oil to ensure repeatability.

In terms of peak numbers, we found that the engine gained nearly 7 hp with the thinner conventional oil, and was up nearly 10 hp with the synthetic. No peak torque gains were observed by changing from 20W-50 to 10W-30 conventional; however, the synthetic was up 15 lb-ft of torque at the peak. Looking at average numbers helps explain where the gains occurred--both the thinner conventional and synthetic oils broadened the torque and power bands overall, but the thin Mobil 1 showed the greatest improvement under 4,700 rpm, indicating that the thinner oil provides less initial drag for the engine to overcome."

Steve

 

I have been running the Mobil 1 15W-50 for a number of years now. You are correct that a thinner oil has many benefits but less so on an older engine with some mileage on it and bearing clearances that were much looser than modern engines. I also primarily drive my L-82 only in warmer weather so I am not concerned as much about the thinner oil at startup. As stated before, only Mobil 1 15W-50 has the correct amount of ZDDP for flat tappet cammed engines. I could use others like the Amsoil 10W-30 but don't. Would I use a 15W-50 in a modern engine? No. I actually use 5W-30 synthetic in all the other cars and Euro Formula Mobil 1 0W-40 in my 2010 Z06 (recommended by GM for European Z06's by GM BTW) instead of the 5W-30 recommended by GM.

Mobil says about its 15W-50:

"Mobil 1 15W-50 is also recommended for older valve train designs that may benefit from a higher level of anti-wear normally not required for newer generation vehicles."

I am comfortably with that endorsement from Mobil and have had zero issues over a number of years.

I also know the oil temperature that my L-82 4 speed (3.70 gears) on the highway on hot days cruising at 3,500-4,000 RPM. The 81/82 oil temp gauge that I installed years ago will go as high as 250 degrees! The L-82's are known to run very high water and oil temperatures! Would you trust a 5W-30 or 10W-30 oil at those temperatures?

Lastly, obviously, Mobil 15W-50 is NOT a 20W-50 oil and is a compromise between current 10W-30/40/50 oils and a 20W/50 oil. Most engine wear occurs at startup as stated and synthetics flow much better than conventional oils of a similar weight at a given temperature, especially cold temperatures.

Does that answer your question?

 

It does, thank you. I ran incorrect viscosity oil for a number of years as well I still think you and your engine would be better served running an oil like the Amsoil I mentioned in 10w-30, but don't think I'm going to change your mind And that's perfectly fine

By this you mean in this viscosity range I assume?

There are plenty of others in other viscosities: http://forums.corvetteforum.com/c3-t...ppet-oils.html

 

The only Mobil 1 synthetic oil with 1,200 ppm ZDDP is Mobil 1 15W-50!

 

Has / does anyone sent their favourite motor oils for VOA analysis - I'm talking unused (new) oil.
I am primarily interested in conventional oils.

I just took some new oils to get tested yesterday : Delvac 1300 10w30, NOS ESSO Protec SJ rated 10w30 and some tractor oils LOL

 

I am using Joe Gibbs products. Initially I will use the conventional blend until the engine is broken in then I will switch to the synthetic.

My engine builder recommended such products as Joe Gibbs, Redline, or Brad Penn. They specifically sent info. with my engine about the need for ZDDP in the engine oil that is to be used in my engine. The argument could go on endlessly about engine oil, however I will go with the recommendation of my engine builder.

They have been building engines for over 25 years, I think they probably know more than I do about the oil that works best in their engines. JMHO.

 

"Oil categories for gasoline engines:

• Over 90,000 psi = OUTSTANDING wear protection

• 75,000 to 90,000 psi = GOOD wear protection

• 60,000 to 75,000 psi = MODEST wear protection

• Below 60,000 psi = UNDESIRABLE wear protection"

My question is, what psi are my bearings subjected to under maximum load for let's say a 450 HP 355?

 

does anyone know if Delvac 1 is still made and how it stacks up

 

You can read VOAs for weeks here : http://www.bobistheoilguy.com/forums...oard=11&page=1

 

Yeah I've been there - if they are more than a year or two old they are "obsolete" and I believe last time I tried on "Bobs" it was very difficult to find specific oils (or the ones I was interested in).

Thank you

 

Here is the last time I am going to say it. My friend owns a huge machine shop and is considered to be the best in the business. He builds engines for "Dream Car Garage" don't even know if that is on the air anymore. He also builds engines for the "Cigarette" style racing boats with multiple engines that see high RPM's for extended periods of time.

Anyway he was starting to see flat tappet cam failures a few years back. Took him a while to figure it out but he now puts in Brad Penn 10W40 or more commonly 20W50 Brad Penn semi-synthetic oil in every engine that leaves his shop.

He is in the business to make money and an oil related problem costs him plenty before he figured it out. It is quite simple:

Put in Brad Penn semi synthetic oil in your engine and you won't have a problem, if you listen to this advice you are not going to have a problem. My $15,000 427ci is 5 years old now and it runs like a clock, theres a million different oils out there trying to sell you there product. You don't need to test them all BRAD PENN SEMI-SYNTHETIC that's all you need to know

 

I "hear" what you are saying Wayne.

But I am not getting into 'boutique" oils - I drive my car on trips and don't want to worry about, if need be, trying to chase up Brad Penn, Joe Gibbs etc etc oils when I'm out in ****-intercourse Egypt.

I built my motor in 1978, I started off using ESSO HD oil back then (can't remember I think it was a "truck" oil).
It is an old motor - I do not want to find out the hard way that there may be issues with synthetic oil in this motor.

Thank you for the address for Wear Check : yesterday I dropped off samples of 4 different oils for VOA for my own curiosity/knowledge.

I also submitted a sample of the GL6 75W90 gear oil that I have a drum of and have been using in my tranny's and rear ends for the past 25 years.
Just curious about the yellow metal corrosivity - I haven't had any great tranny or synchro problems but wanted to see how it checks out.

 

Oil seems to be a very personal thing around hear but I like to fall back on what I've experienced.

1) we rarely had wiped out cam lobs back in the 80s then they messed with the oil and all of a sudden cams are getting wiped out left and right.

2) I saw the Rotella comment and I use it! Any oil that can handle a screaming turbo with 22:1 compression and is the only engine still made with a flat tappet cam, I think it can handle our little 350s with 230 HP.

3) I do use Mobil 1 in all my newer vehicles, including Harley's, LQ9 SS Silverado, 6.2 escalade and it works great!




Now for our original poster, he say under acceleration he hears a knock 400 miles after an oil change.
My first question, what is the oil pressure at idle, cruising and when motor is cold???

 

Easy, such anecdotes mean nothing and prove nothing except that people repeat stories for which they have no evidence.

 

This is so true. We have serviced thousands of engines in the last 30 years. Chevy, Ford, Chrysler, evern Volvo. Never have we seen any cam damage. We still service engines from the mid to late 60's and all are running our synthetic oils which are also running in brand new 2013 engines. All are 15W40, for push rod, 5W40 for OHC

 

Thanks for all the help guys. You put me over the top with info. Today I starting putting your advice to work. After running and revving the engine, and watching for falling parts- having seen none. I took a short trip. I drained the oil level down to below full, added 6 ounces of Marvil. drove 8 miles, flat surface. Every time the engine was underload, I heard the knock, still the same. I stopped at my friendly neighborhood garage on the way home. Within minutes, the mechanic pinpointed the noise to an exhaust header leak. I feel a little stupid, but I did not rule out that possibility. I can honestly say that I have never in my life heard an exhaust leak make so much noise. Car hits the shop this week, problem solved. And best of all it is a cheap fix. Thanks for your input.