New GM EOS

[Guest TwoDoorBuickMan]

I recently ordered some of the new GM EOS PN 88862586 from www.gmpartsdirect.com. It arrived today and the label says it contains Zinc Dialkyldithiophosphate (ZDDP). It did not indicate the concentration.

[serb]

I ordered a bottle from the Buick dealer back in October when I got an oil change before parking it for the winter. The EOS came in about 2 weeks ago. From what I understand, an ounce should be enough. ???

Stevo

[Guest TwoDoorBuickMan]

I have read a lot of articles and the one that seemed most credible suggested 1/2 oz. per quart of oil. When I did the math based on 8000 PPM ZDDP in EOS and 800 PPM in SM oil with a target of 1200, the 1/2 oz. per quart seemed right. The only unknown is whether or not the new EOS contains 8000 PPM as was contained in the old EOS. I intend to use 4 oz. per change.

[NTX5467]

How much zddp is in the prior "pint" and newer "Assembly Lube EOS" container have been discussed and listed at www.bobistheoilguy.com and also in a spreadsheet at www.lnengineering.com. The latter website is concerend with Porsche air-cooled racing engines, where zddp can be important.

The LNEngineering website commented that the smaller "new" EOS concentrate has enough zddp to basically put newer SM oils to where the prior SL grade oils used to be (zddp-wise).

We have some of the "new" formulation. The dialogue on the bottle specifically mentions "Assembly Lube" rather than "oil additive". Be that as it may . . . whereas the prior packaging mentioned "assembly lube" and "oil additive".

My more recent research (aided by the LNEngineering website and it's import vehicle orientation) reveals that many European diesel engine manufacturers (passenger cars rather than "truck" engines) have they own particular oil specs and "approvals". VW in particular. These oils are "SL", synthetic, and usually 5W-40 viscosity. If the particular engine's "approval spec" is not on the oil container, use of an alternative non-approval oil can lead to engine damage down the road. It's a more intense situation than with USA-brand engines, both in manufacturer approvals, viscosity ratings, and change intervals.

In the case of VW, Audi, and BMW, they have particular oil specs for particular engine families--gas and diesel. Mercedes has some approval specs also. The oils in VW and BMW dealership packaging are typically European formula Castrol oils in particular viscosity ratings (some of which can be purchased in Castrol packaging at AutoZone, with the particular manufacaturer approvals and "Made in Germany" on the bottle). These oils are typically "SL" API-rating oils and do not meet the lower-zddp specs of the GF-4 specs.

The LNEngineering website and blog has a link to a spreadsheet with oil analysis results dating back for about 10 years for various oils which were used in a variety of engines. LOTS of information to work through! Plus "virgin oil analysis" for unused motor oil and additives. Seems some of the STP additives also have a good dose of zddp in them too. Enough articles, blog comments, links to other European vehicle blogs/forums, and informative articles to keep a person busy for a few weeks!

The bobistheoilguy forum also has oil analysis spreadsheets and such too, for "virgin" and "used" oils.

One important thing is that the newer forumlations of "diesel oil" (i.e., Rotella T and Chevron Delo 400) are now upgraded to "SM" specs with their latest formulations for the new lower sulphur content diesel fuels. As diesel-oriented oils, they don't have to meet the GF-4 spec, which seems to be more important than the "SM" spec as to zddp levels. So, the original blanket recommendations of using Rotella T 15W-40 might not be as applicable now as when they were originally made. Plus, CompCams and others now have their own oil additives to help combat the camshaft wear issues not present in the pre-"SM" times.

"SM" and "GF-4" typically hit at about the same time, so "SM" was keyed-upon by USA users as the oil to stay away from for flat-tappet engines when it was more "GF-4" which spec'd the lower zddp levels in the oil (for emissions systems longevity on gasoline-fuel engines). I've got some files from the Castrol website (from last year) which noted zinc concentrations of the desired .12% level in their popular oils which also met SM and GF-4 specs . . . for what it's worth, while they still had that information in the data sheets.

Also, it seems the oil company websites are updated less often than the oil forumuations might be. This is where the speadsheets on the oil analysis come in handy (with dates the oil samples were analized).

If "SL" oils are what you desire to "key" on, they are still out there in USA brands . . . just not always in multi-viscosity oils. As in straight 30 viscosity oils, for example. Mobil 1 also has a newer oil which is "SL" and synthetic, which is a switch from their existing "SM" synthetic oils. Just have to carefully read the back of the oil bottle!

Just some thoughts . . .

NTX5467

[Jim Cannon]

I found the following discussion and table from Mobil 1 helpful:

http://www.mobiloil.com/USA-English/MotorOil/Car_Care/AskMobil/Zinc_Motor_Oils.aspx

They have the synthetic Mobil 1 15W50 oil with the higher (1200 ppm) ZDDP. My main complaint is that I don't put synthetic in my '63 Riv. For the short distance I drive in 6 months, it's not worth the added cost.

I contacted them about this. Their conventional Mobil Clean High Mileage 10W40 has 1000 ppm of ZDDP, which is not too bad.

http://www.mobiloil.com/USA-English/MotorOil/Oils/Mobil_Clean_High_Mileage.aspx

This spec is not on their web pages; I had to call them to get it. (800-662-4525)

They told me I would have to use their Delvac 1300 motor oil 15W40 to get 1200 ppm in a conventional oil. I am going to look around for it (they say it is at truck stops) and might use it for the next oil change.

I did not tell the guy on the phone that I worked for ExxonMobil when I quizzed him about this oil, and I quizzed him pretty hard.

[NTX5467]

You can probably find Delvac 1300 at WalMart. The ones up here have it right next to the Shell Rotella T products.

Thanks for the links! It's good that you found somebody that knew what you were talking about as others (in other forums) have mentioned spotty luck finding an oil company rep who might say more than "the company line" on oils for older vehicles (and what was in them).

NTX5467

[Guest TwoDoorBuickMan]

GM EOS PN 88862586 is the replacement for the old EOS (Engine Oil Supplement) PN 1052367. This was an assembly lube used to break in flat tappet cams, and also used by many racers as an engine oil additive. When the API formulation of engine oil changed from SL to SM, The amount of ZDDP was reduced by about 1/3. ZDDP was an additive that helped prevent camshaft and lifter wear on older engines. Newer engines with roller lifters and overhead camshafts no longer needed it and there was concern that it would contaminate catalytic converters. The old EOS was a good source for ZDDP as it contained a high concentration. The old EOS was discontinued and the rumor was the new EOS would not contain any ZDDP at all. It has been hard to find and when I finally located some, I was glad to find it did contain ZDDP.