Engine oil article

[Duke W.]

The engine oil article I authored that was originally published in the Summer 2008 Corvette Restorer has been republished by the St. Louis Chapter in their newsletter, The Legend, and it's available online.

http://stlouisncrs.org/news_files/St_Louis_NCRS_Chapter_July_2011.pdf

The text has a few minor edits for clarity and updates including the new API service category SN. (The same text version is also being published by the national SAAB club.)

Given the recurring oil questions, I suspect that many can use a refresher course on the subject, and newer members from the last three years probably didn't get that issue of The Corvette Restorer.

Duke

[Scott S.]

Re: Engine oil article

Thanks Duke.

[Ken T.]

Re: Engine oil article

My virus protection found malware when I clicked on the synthetic link.

[Duke W.]

Re: Engine oil article

What are you talking about? If there was a problem with a link in the article, please post it here.

There was no "synthetic link" in the article.

Duke

[Ken T.]

Re: Engine oil article

This one:
http://lubricants.s5.com/

[Ken T.]

Re: Engine oil article

I tried it again and got the same thing. My Avira spyware says the link tries to install malware when I click on the link. Check it out, maybe I don't know what I'm talking about.

[Michael W.]

Re: Engine oil article

No problem here with that link

[Duke W.]

Re: Engine oil article

I don't have any spyware on my computer. I think it can sometimes be overzealous. I just opened the site using Firefox with cookies disabled, and along with the page coming up I got a warning: "Firefox prevented this site from opening a pop-up window", which was probably just an ad.

Suggest you contact the site Webmaster:

webmaster@lubricants.s5.com

Duke

[Ken T.]

Re: Engine oil article

I just did an online analysis of the link and most programs said the link was ok, even mine (Avira) except for one: Dr. Web which said it was a malware site. I probably don't know what I'm talking about.

[Dick W.]

Re: Engine oil article

All the links worked fine for me. Using Windows Defender

[Duke W.]

Re: Engine oil article

Unfortunately, the "lubricants university" (sponsored by Chevron) courses are no longer available to the public, which is too bad, because they were very good.

Duke

[John H.]

Re: Engine oil article

Great site Duke! Thank you for sharing your knowledge. I always look forward to your comments on the subject and you have put my mind at ease on several occasions.

[Steve V.]

Re: Engine oil article

Duke,

For the benifit of us non-tribologists out here who have trouble with technical articles, what is "synthetic" oil and is it worth using in modern vehicles with high milage? (100,000+)

Steve

[Duke W.]

Re: Engine oil article

The first thing you must understand is that there is no legal definition of "synthetic" when it comes to engine oil, and even the technical definition is vague.

Synthetic base stocks have two main advantages over conventionally refined engine oil:

1. Wider viscosity range without the use if viscosity index (VI) improvers.

2. Greater oxidation resistance, which allows higher mileage between changes.

It is NOT more slippery than conventional oil.

It does NOT "cling" better to engine surfaces.

The above are two common internet myths.

The API currently segregates base stocks into five groups based on the type of refining process as defined in the API 1509 document and appendices that you can download from the API web site.

Group I: "Conventional" base stocks derived from crude oil distillation and solvent extraction.

Group II: Adds "hydroprocessing" to break up ring molecules and remove undesireable elements such as sulfur yielding more long chain saturated hydrocarbons, which means the molecule consists of only carbon and hydrogen atoms and replaces any double bonds with single bonds.

Group III: Additional hydroprocessing to remove additional undesireable elements as above resulting in a higher percentage of "pure" single bond chain hydrocarbons.

Group IV: Uses a complex petrochemical process to produce polyalpha olefins (PAOs).

Group V: Uses a complex petrochemical process to produce esters.

As one goes up in group number, the resulting base stock has wider viscosity index and more resistance to oxidation.

Group IV and V were developed for jet/turbine engines, which have no internal cooling and expose the lubricating oil to more heat resulting in higher temperature, so lubricating oil requires very high oxidation resistance.

Group IV and/or V was the base used for the original Mobil 1 in the seventies.

In the eighties, Castrol introduced a "synthetic" engine oil using less expensive Group II and III base stocks, which allowed them to underprice Mobil.

Mobil sued Castrol asking the court to order Castol to not call their oil "synthetic", but Mobil lost the case, which forced them to reformulate Mobil 1 using Group II and III base stocks in order to remain price competitive.

As API service specifications evolved, the oxidation resistance requirement has become more strick, so even "conventional" oils have some Group II and III added in order to meet the current oxidation requirements. This applies to both S and C-category oils.

Base stocks with higher oxidation resistance and "oil service life monitors" is what allows modern cars (like modern Corvettes) to accumulate 10-15K miles of daily use before the oil needs changing, however, for warranty coverage, GM still requires at least an and annual change, regardless of mileage.

I generally recommend annual oil changes for vintage cars that accumulate a few hundred to a few thousand miles per year, but if the engine is tight, the PCV system effective, long enough trips to allow the oil to fully warm up, and the car is kept in a garage, I don't see a problem going two years if only a few hundred miles are driven annually and the oil doesn't darken significantly in the first year.

Today's conventional base stocks have much more oxidation resistance than when our cars were new, so the oil doesn't degrade as fast.

Also, since we typically only start and drive our vintage cars in mild weather we don't need a OW-40 engine oil; 15W-40 is more than adequate.

Based on the above facts, the question is: Is there a benefit to using "synthetic" oil given that it costs two to three times as much as conventional oil for either a freshly restored vintage engine or a high mileage original engine?

I'll let everyone answer that for themself.

Duke