'98 Silverado 4x4 w/350, three different oils

[twb]

Below are the results of three successive oil analyses, with three differents brands of oil. I now know that comparing the results isn't completely fair because the additive packages of different oils may compete or counteract each other. Still my naive evaluation tells me that Mobil 1 isn't all that's it's touted to be, By the way that was the older Tri-Synth (the "good" stuff). Castrol Syntec looks like it did pretty darned well. The Syntec was run late spring to early fall, so it was exposed to warmer temps (OK, it doesn't get all that hot in upstate NY) and boat towing. The iron number for Schaeffer's bothered me a little bit, but that lead number is very important as the main bearings in this engine utilize lead.

The vehicle is a 1998 Chevy Silverado 4x4 with a 350 engine (the "old" style 350). It sees mostly highway miles, and I don't drive it hard.

One last observation, and I made this observation in my post about my Passat. Although the silicon numbers are almost identical, the first and highest was when I still had the OEM paper element air filter installed. The other two were with a K&N filter installed. I don't feel so nervous about K&N anymore.

One last thing, all oils were 5w-30, and I think I used a Purolator Pure One for all of those changes.

code:

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brand of oil Mobil 1 Castrol Syntec Schaeffer's

miles on sample 5000 6700 5400



vis. 100C 10.7 11.1 11.3

% oxd. 24.4 25.6 27.8

% nox 37.1 31.4 25.7

TBN 9.9 8.4 4.9

iron 36 23 35

chromium 2 1 1

lead 52 50 34

copper 7 5 5

tin 6 4 4

aluminum 1 8 8

nickel 1 1 1

silver 0 0 0

mangenese 1 1 1

silicon 27 24 23

boron 59 35 35

sodium 21 11 128

magnesium 2194 602 304

calcium 1236 2097 1699

barium 0 0 0

phosphorous 1006 1124 1012

zinc 1247 1215 1152

molybdenum 9 26 76

titanium 0 0 0

vanadium 0 0 0

cadmium 0 0 0

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[BOBISTHEOILGUY]

A couple of comments if I may...

on the Schaeffers, from the looks of the Mo, this would be the first oil change with schaeffers as it is lower than normal thus indicating it using alot for intial plating.

Second is that the tbn is dropped from 8 to 4.9, also indicator of first oil change as with Mo. Also with oxidation levels showing that percentage, it is using more than normal for digesting any old additive / acids from previous oils.

As a second and third oil change is analyized, you'll find that these numbers should stablize out some, the Mo will be slightly higher and unless some kind of acids from the blowby of fuel system is involved, then the tbn should also increase slightly.

 

[MolaKule]

Bob,

I attempted to post this question the other dat (Monday) but it didn't get through somehow.

On the Scheaffer's, why the high value of ZDDP if Moly is sufficient for boundary lubrication?

(Both are boundary lubricants, which deposit an organometallic layer on the rubbing surface).

Or, are they simply trying to cover all bases?

 

[BOBISTHEOILGUY]

Interesting enough both are used as antiwear but one is an extreme pressure additive more so than the other.

the ZDDP, I have(experimenting with the timken mach) found will coat the bearing almost immediatly thus providing a quick basic barrier lube protection like most oils do. This I have found to work quite well for standard oil applications and with a little more pressure than normal, can be sheared through and cause it to stop the bearing.

Now moly on the other hand, uses heat to activate as it actually bonds to the metal. I suspect with heat, the metal pores are open and the moly reacts to the heat, thus plating on or maybe into the metal surface to some degree?.

I know that it takes the bearing more time for the moly to bond and create the barrier than with zddp.

Now in this instance, I have bonded up the barrier additive moly to the bearing after allowing it to plate up with the heat, and with a much higher extreme level of pressure, have accomplished pushing through its barrier to stop the bearing. BUT... unlike the ZDDP, when I let it sit like overnight after plating it, and come back to it the next day having been cooled down.. I then try to break through it again, this time after having removed the oil from where it is suspended, I can lay the whole wieght of my body against that lever(280lbs) at maybe a 6to1 leverage?, and I cannot stop that bearing. This seems to have impregnated itself within the asperities of the metal(due to the heat?) and therefore makes it near(not totally) impossible to shear off.

So, from what I see, I think they use the zddp in addition so to coat up the surface for immediate results and as the high friction areas create heat, the moly settles into those areas.

This is one of those things where you can see the difference between coating a suface and bonding to a suface.

Another point is that this timken test doesn't really allow the full amount of moly plating to occur as I only run it for several minutes there fore there is only a few plates having found its way to the surface. So I'm actually working against just a few. This is why redline makes the comments on how their oil actually gets better the longer it runs. Same with Schaeffers, the longer it is run, the more plating it does and eventually has completly coated all surfaces where heat was a real problem and then goes into a maintain mode of replacing the sacrificial moly additives as it gets used up.

This is why when looking at an oil analysis, you can generally tell if it is the first oil change with schaeffers as the moly levels are normally lower than with the next consecutive drains where it is maintaining the moly boundaries that were first plated.

 

[Patman]

Very informative post Bob! (as usual!)

I'm curious as to how long the moly will stay on the parts after one has switched to a different oil?

In my case, I'm draining out the Maxlife this weekend (and sending it to Terry!) and will be putting in Auto-rx and Castrol. I'll drain that out after 500 miles and put in more Castrol. I'm going to send that sample off to Terry as well and it'll be interesting to see if there is any moly in that oil. I'm wondering if it's even worth it to run the Castrol that long and sample it, or should I just switch back to the Maxlife again after the Auto-rx treatment has stopped the leaks? I wanted to get an idea of how a dino oil would hold up after a 2500 mile interval, just for comparison's sake.

 

[VaderSS]

Using this logic, it seems that the reduction of Zinc in Mobil 1 and the addition of Moly, will make it perform even worse for the 4 ball, but better over the long run. Does this sound right?

 

[Patman]

That sounds about right to me, now we just need to figure out exactly how much moly is in the new Mobil 1. I hope it's not just a teeny tiny bit then that means it'll probably do nothing at all.

How much moly is the minimum amount to do any good Bob?

 

[MolaKule]

BobIs,

Well, first of all, any coatings in machines are sacrificial because they either get rubbed off or they fall back into solution or suspension.

The data I have seen suggest that most anti-wear ingredients only start to react at
higher temperatures, regardless of whether they be ZDDP or Moly. Now, once they coat the
parts, they do provide start-up protection; star-up friction 4 to 5 times middle-temperature
driving friction.

One more question about Schaeffer's, have they done any engine tear-downs after say
40,000 miles to inspect the valve stems for wear and valve surfaces for deposits?