Running STP oil treatment in a classic engine?

[elagache]

Dear mid-60s Buick caregivers who are fussy about the oil you run in your engine,

Its time to get some oil for my trusty wagon's engine.  Of course this item fell off to the last minute and I'm desperately short on time.  I found that Amazon sells Joe Gibbs 10W-30 conventional oil and I only need 4 more quarts to fill the engine up.  Mike Tomaszewski wanted me to stick to conventional oil for one more round before any short of synthetic.  I want to switch over to Brad Penn semi-synthetic, but I think Joe Gibbs will due for this last round of conventional oil.

However, Mike Tomaszewski offered me some other advice that I'm not so sure about.  He runs STP oil treatment in all of his cars.  Well, not knowing that the stuff is, my first instinct was to get my hands on the Safety Data Sheet which is here:

http://www.stp.com/sites/default/files/STP%20Oil%20Treatment%20%282015-06%29.pdf

The ingredients are:

Mineral Oil and Petroleum Distillates at over 60-100% and

Calcium long chain alkylphenate sulfide at less than 5%

Okay the main ingredients are refined oils that's harmless enough.  However, what in the is Calcium long chain alkylphenate sulfide? 

Another web search led me to this page describing these products:

https://www.lubrizol.com/Corporate-Responsibility/HSES/Product-Stewardship/Alkyl-Phenate-Sulfides-in-Engine-Oil

In short these are some of the "detergent" products that are used to get contaminants off engine parts and into the filter.  Well, that isn't exactly good news.  When Jim Weise wrote up what he learned from a Joe Gibbs presentation:

http://www.v8buick.com/index.php?threads/new-oil-tech.222499/

One of the concerns that was mentioned is to have too much detergent in a classic car oil.  The whole idea is that ZDDP is present in the oil to coat parts like the cam.  Detergents can literally impede ZDDP for clinging to those parts.

So I decided to search the web for any references to using STP oil treatment in classic cars and I found this post on the Vintage Mustang Forum:

http://forums.vintage-mustang.com/general-discussion-non-vintage-mustang/618838-amount-zddp-stp-oil-treatment.html

In it there is a the text of a letter sent to the author from STP.  The key bit of text is below:

"Our STP Oil Treatment contains the zinc anti-wear agent ZDDP. This ingredient was once found in most motor oils. If you add one 15 ounce bottle to four to five quarts of oil, it will provide the same protection as the older motor oils once provided. The amount of ZDDP in the product is proprietary. Many classic car owners with flat tappet cam motors use our product for this reason. "

So STP adds detergents and ZDDP.  Going back to what Jim Wiese learned, it is probably best to either use an additive or use an oil specifically formulated for classic car engines.  Since I want to do the later, it seems to me that I shouldn't add STP oil treatment.

However, the whole point of this exercise is to ask you'all about this.  So do any of you run STP in your classic cars?  Why or why not?   

Opinions solicited!!

Cheers, Edouard 

[Brian]

The best stuff I have found on the market is the comp cams break-in additive.  Add a bottle of it to your engine and use conventional modern day engine oil with it.  It adds the needed ZDDP to the oil for the cam. I buy it by the box from Summit racing.  It is about $13 a bottle.  Put a bottle in every time I change the oil in the vehicles with flat tappet cams. 

[cwmcobra]

I think I'm going to use the recommendation of the local engine machine shop where I had my block machining and cylinder head assembly done.  They sell Brad Penn oil and suggested that I simply continue to use the Brad Penn breakin oil even after breakin is complete.  They said the breakin oil has a high concentration of ZDDP and it is no problem to continue its use.

Another option to consider.

 

Chuck

[WkillGS]

I've heard of STP containing ZDDP, there was discussion years ago about the red bottle formula vs the blue bottle formula. ZDDP content may have changed since the 2010 discussions, it may not have as much as it used to?
IIRC, ZDDP can damage cat converters, hence the phase out. Is STP safe for newer cars? If it is recommended for new cars, ZDDP content is likely low.
You're probably best off just using the Brad Penn oil since it's formulated for older cars.
I use an additive called ZDDP plus. May be similar to the Comp Cams additive Brian mentioned. I think Lucas oil has a version too.

Stock Nailheads don't have high valve spring pressures or are used at very high rpm's, so the lifter wear fear isn't as critical as a serious street/strip engine.

The guys on the 'Bob is the oil guy' forums should have some updated recommendations.

[elagache]

Dear Walt and mid-60s Buick caregivers,

I've heard of STP containing ZDDP, there was discussion years ago about the red bottle formula vs the blue bottle formula. ZDDP content may have changed since the 2010 discussions, it may not have as much as it used to?
IIRC, ZDDP can damage cat converters, hence the phase out. Is STP safe for newer cars? If it is recommended for new cars, ZDDP content is likely low.

I was wondering the same thing because yes ZDDP was phased out because it was "poisoning" catalytic converters.  Yet, here is the current webpage for STP:

http://www.stp.com/products/oil-additives/oil-treatment

No mention that it should not be used on modern cars.  Very strange! 

You're probably best off just using the Brad Penn oil since it's formulated for older cars.

That's my plan at the moment.

Cheers, Edouard