Costco 15x40 diesel oil zinc content ?

[Robert B.]

Anyone know the zinc content of this oil Thanks

[Duke W.]

Re: Costco 15x40 diesel oil zinc content ?

I'm not a Costco member and haven't been in one for awhile, but I recall seeing Chevron Delo, sold in 6 1-gallon cases. The current P limit for CK-4 is 1200 PPM, which would put the Zn content at about 1300-1400. Recall from my oil article that it's P that's limited not Zn, and Zn content is usually 100-200 PPM greater than P.

Most Ck-4 brands have data sheets online that list chemical properties, and there are also third parties that do chemical analysis on multiple brands.

Beginning with CK-4 some may have much less P than the limit. This is because there are newer Boron-based anti-wear additives, most of which are patented that can allow the ZDDP level to be reduced. The bottom line is that Ck-4 is CK-4 and it's all the same... all the same, regardless of the P or Zn content.

All have to pass the same test suite including wear tests regardless of the chemical analysis. Selecting among CK-4 oils based on Zn content is an ill-informed criterion.

Being as how all CK-4s are effectively the same I buy the least expensive I can find when I need oil, and that's usually Walmart's SuperTech house brand.

Duke

[Bill B.]

Re: Costco 15x40 diesel oil zinc content ?

If you haven't already read Duke William's .pdf about engine oil for vintage engines, here is a link:

St Louis NCRS Chapter (az356outlaws.org)

Duke advocates the use of Diesel specification oil, as I understand, the API mandates the content of ZDDP in order to carry the API badge rating in Diesel engine oil.

I'm sure Duke will respond to you on this question.

[Bill B.]

Re: Costco 15x40 diesel oil zinc content ?

I see Duke beat my response by 3 minutes as I was still typing!

[Duke W.]

Re: Costco 15x40 diesel oil zinc content ?

Duke advocates the use of Diesel specification oil, as I understand, the API mandates the content of ZDDP in order to carry the API badge rating in Diesel engine oil.

The API only has a maximum limit on P, a component of ZDDP, because its understood that P can degrade catalyst performance over the long run.

A common myth is that the "EPA" established the limit but that's not true. What the EPA DID do is mandate longer emission control system warranties, up to 100K miles, and THAT is the reason why the API began to establish P limits going back to SL about 15 years ago.

The current S-category P limit is 800 ppm and 1200 ppm for C-category. The current S-category limit is okay for modern engines that have "roller everything" valve trains, but vintage engines have sliding surface valve trains, so the tougher C-category wear test and more allowable P means that C-category oil is a better choice for our vintage engines.

The industry is looking for alternative anti-wear additives to ZDDP and some boron-based proprietary additives are partially replacing ZDDP in some C-category brands, but the lower P content in NO WAY means that the oil is inferior in wear protection. because whatever anti-wear additive package used has to pass the same C-category wear test, which is tougher than the S-category wear test.

P and Zn content is no longer a reliable indicator of a given oil's wear protection.

The bottom line is easy: Buy the least expensive current C-category 15W -40 that you can find. No one brand is better or worse than any other. Brand is irrelevent and if you plan on driving the car temperatures below about 15-20F use the 5W-40 version.

Duke

[William F.]

Re: Costco 15x40 diesel oil zinc content ?

After all the years of stressing importance of adequate P how do you and we know the oils with reduced P but with boron are adequate for flat tappet cams? Seems like a reversal of recommendations. What does Crane cams say?

[Duke W.]

Re: Costco 15x40 diesel oil zinc content ?

Read post #5. Crane is long gone.

Duke

[William F.]

Re: Costco 15x40 diesel oil zinc content ?

I read and understand post 5. But all these years we've been told must have 1200 P for flat tappet cams. Now boron and less P is fine? Do any diesel motors have flat tappet cams or they all roller cams now?
On similar thread, several major oil companies( Shell X100, Castrol Classic, etc) are now marketing S rated oils specifically advertised as having ZDDP for older cars with flat tappet cams. Most are what I would think too high viscosity , though 15-50. Have you seen spec sheets on these?

[Duke W.]

Re: Costco 15x40 diesel oil zinc content ?

I don't have answers your questions, so you'll have to do your own research. I'm presently satisfied that Walmart's SuperTech house brand 15W-40 CK-4, which is usually less expensive than the national brands is more than adequate for my vintage cars with sliding surface valve trains.

Duke

[William F.]

Re: Costco 15x40 diesel oil zinc content ?

Thanks for reply, Duke.
Think I'll stick with the Shell Rotella T CK-4 10w30 that I've been using. For those who also use Rotella T, be sure it's "C" rated since some is for gasoline engines and rated just "S" (spark). Have to look at label.