Re: If you read through the archives on this

[Greg A.]

Duke, I'll jump in here. As somone who works for a major oil company and has worked in the lab and marketing and sales with finished lubricants for 22 years, I've heard this discussion hundreds of times.

Duke has the pros and cons of synthetics down. The major advantages are at extremely high and low temperatures. The average driver doesn't go for extended drains and doesn't see the advantage of long base oil life. I definitely agree on using more heavily compounded diesel engine oil in a classic vehicle. There is very little difference in additive packages between mineral and synthetic PCMOs (Passenger Car Motor Oils.)

Without confirming who makes John Deere's oil for them, I can say that it is a formula specific for John Deere and is not just a rebrand of any other major oil brand. Deere has their own thoughts on some performance specifications.

Thanks Duke for the plug for Delo...the number one brand of heavy duty deisel oil. Now, do you know what Delo stands for?

As for the synthetic leakage issue, here's what the research people I know have told me. If an engine first uses a mineral oil of low quality that may contain some naphthenic base oil (with cyclical rings) the seals may experience some swelling as the naphthenics are drawn into rubber seals. If you subsequently switch to a PAO or SHC based engine oil (which most all are with some esters thrown in to improve additive solvency), the naphthenics are drawn out of the seals and the seals shrink a bit, causing leaks. It is now common for most synthetics engine oils to contain a seal swell agent to reduce this shrinkage effect. The two biggest problems in formulating synthetic oils appears to be the seal swell and the additive solvency issues. The base oils are so "pure" that there are no "loose ends" for the polar detergent/dispersent additives to be attracted to and stay in solution. This seal leakage issue is not as big a problem today with modern engine oils (both mineral and synthetic.)

Sorry for the long post, but there seems to be considerable interest in the issue.

Greg.

[Duke W.]

Re: If you read through the archives on this

Greg - It's nice to get some real scientific input from an industry professional to dispell all the myths and misinformation. Guess you must be with Chevron, eh? Or I guess it's Chevron-Texaco now.

Delo stands for "diesel lubricating oil", of course. I learned that back in the early sixties when I changed the oil on the big rig. I think it took a case (24 quart cans) and a half to fill it back up, so they had the "kid" drain the oil and spend the half hour plus pouring in the quart cans.

Duke

[Craig S.]

Re: If you read through the archives on this

Greg and Duke - a big THX on all the information on this question, it certainly has made me switch my thoughts. I have one additional question though....specifically related to protecting high force non-pressurized areas such as cam lobes. I had always heard that synthetic oils had superior film strength and protection of these wear surfaces, I even recall some study about a cam comparison after 200K miles in a cab or something showing markedly less wear on the cam lobes. If using a fairly stoudt spring on a mechanical cam (in my case, an original GM blueprint cam for the 3143 with the GM springs) is there any less tendency of wear on the cam lobes during break in and overall life of the vehicle? There always used to be the thought to switch to synthetic after ring seating, I am assuming this is another urban legend with current ring technology and moly coated rings on smoother cylinder surfaces. Thx again guys!...Craig

[Greg A.]

Re: If you read through the archives on this

Craig,

Cam lobe lubrication is typically in a regieme called "boundary lubrication" where you do not have enough of an oil film created to induce hydrodynamic lubrication. Anti-wear additives are used for boundary lubrication conditions (you have the same boundary conditions at start-up for most of the engine.) Zinc di-alkydithiophosphates (ZnDTP) additives are traditionally used for AW protection, specifically for cam lobe wear. These additives are the same whether it's mineral base oil or synthetic.

The oil film thickness is directly related to the oil's viscosity, so at high enough temperatures, you will see a greater oil film thickness with a synthetic than with a straight grade mineral oil. If you are using a multi-viscosity mineral oil, the difference in viscosity at a given temperture doesn't become significant until you exceed 225-250F, which is greater than the oil temp for most of our engines. In theory, a synthetic "may" give a miniscule increase in oil film thickness on the cam lobes, but the AW additives are really there doing all the work and they are the same, regardless of base oil. In fact there are only a couple additive companies that sell packages for Passenger Car Motor Oils. This is really a competitive area and most packages are very similar. This is an area where the oil company has the base oil and the additive company gives the "recipe" of using so much of their addtives to meet the API SL (the most current classification.)

Greg.

[Craig S.]

Re: If you read through the archives on this

Well, I now know more than I ever did before when it comes to oil and additives! Sounds like Chevron Delo 15W40 is the way to go for a vintage car!

At the risk of starting a whole discussion on additives (which I usually just rely on the oil supplier to include in thier product)....what is in the products all those infomercials use with zero oil psi, putting garbage in a running engine, etc, etc...plus the demo of the friction on the metal roller with a lever...is this some type of product that coats the pores of the metal with a friction reducer that is in any of these other oil additive packages? Thx!...Craig

[Al Corelli]

Re: If you read through the archives on this

To the best of my (limited) knowledge, it is Chlorine Bleach. Yup, concentrated Clorox.

AC

[Greg A.]

Re: If you read through the archives on this

You got the chlorine part right, but they're usually chlorinated paraffins (something quite different from bleach.) Chlorinated paraffins are great extreme pressure (EP) additives and typically are found in metalworking fluids and sometimes in industrial gear lubricants. The problem with using them in engine oils is that with the by-products of combustion, you turn the chlorine into hydrochloric acid. So you get great short-term protection if you forget your drain plug and run to the grocery store. However, you sacrifice long-term engine life with internal corrosion of ferrous and aluminum alloys. No major oil company or engine manufacturer recommends the use of these products (some of the well-known aftermarket additives with chlorinated paraffins are Dura Lube, MotorUp, Prolong.)

The other major type of aftermarket additive is based on Teflon (PTFE). Slick 50 is the popular product. The effectiveness can be debated, but my experience is that none of the PTFE ends up on the cam and it all finds it's way to the oil pan. There has been at least one case where this coated the oil pick-up screen with the expected results.

There's an article that's been widely reproduced on the 'net that explains a lot of this. It's 10 years old and I don't agree with all of it, but you can read it yourself at http://www.vettenet.org/oiladds.html

Greg.

[Greg A.]

Additional Website Link to Additve Lawsuit Claims

I just found this site which updates the status of numerous lawsuits against the aftermarket additive companies: http://neptune.spacebears.com/cars/legal/index.html