Zinc - perfect storm of glowing glitter

[paulswagelock]

Was having a spirited debate about using diesel oils in gas engines (racing and marine). One of the well respected members swears everyone off of using diesel oil in gas engines based on his description below. I tend to disagree with this as a possibility. Thoughts?
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His explanation:Merc racing and the NHRA drag race crowd ran into issues with diesel oils some time ago. The Delvac’s, Rotella-T’s, and Dryden offerings all use a heavy metal additive, usually Zinc. Diesels as you know suffer from fuel contamination into the crank case during warm up. The solution is Zinc to provide deposited lubrication upon the lower cylinder walls to prevent piston skirt scuffing as the crank passes through BDC. This finite additive also gets into the combustion chamber and detonates along with the fuel charge. In a lite to moderately loaded gas engine as installed in say a fleet delivery truck, the additive tends to stay in the crankcase.

As the offshore racing crown attempted to use the Shell and Mobil diesel offerings, their knock sensors were mapped showing timing reduction at moderately high to WOT operating conditions. The drag race guys just melted the top rings. The knee jerk reaction was to blame the fuel.
Combustion chamber temperatures in a marine engine operate somewhere in the stratosphere as compared with an automotive application. After altering fuel blends and talking with some of the top researchers in the industry, it was suggested that migration of the Zinc into the combustion chamber was creating a perfect storm of “glowing glitter” which caused pre-ignition and initiated the knock sensors to back out total ignition timing and reduce engine power.

 

[Steve S]

It is easy to put value on internet posts but if you look at the racing oils what do they have at high ppms? yes it is zinc. Zinc - perfect storm of glowing glitter, impressive imagination .

 

[bepperb]

I don't see how moving away from an HDEO would make a difference. If zinc is such a problem (and that's debatable at best) any other oil will have it as well. Most 40 weight PCMO have as much Zinc (1400ppm) as an HDEO.

I guess he now needs to find an oil with none to prove his case. Good Luck.

 

[d00df00d]

This isn't the first time I've heard something similar. From what I've been hearing from the authorities I trust most, including our esteemed Doug Hillary, you want no more zinc than you need.

 

[expat]

What % of Glowing Glitter is in HDEO?
How much 'GG' is likely to enter the combustion area of the engine?
Does Zinc not have a low burning temp?

 

[paulswagelock]

Zinc is about 1200-1400 ppm in HDEO
The listed auto-ignition temperature is for Zinc powder (layer); dust cloud is ca. 680C (1255F).

 

[aquariuscsm]

I`d read on a forum somplace that HDEO`s can be too abrasive for gasoline engines. Fact or myth?

 

[4ever4d]

We'll all find out in 2or300,000 miles when an HDEO oiled gasoline engine fails due to"zinc" in the oil.

 

[bullwinkle]

The flat tappet cam & lifters running without HDEO would fail long before the zinc would cause problems. Wonder how many RPM these guys are running? My Mercruiser manual specs say not to exceed 4500 RPM for any period of time-5500 RPM is usually redline territory for a SBC or BBC-to run higher than that usually requires large amounts of "folding green fertilizer"!!

 

[Doug Hillary]

Hi,
paulswagelock - Well there are always theories but real practical data always wins IMO

I first used HD lubricants during the 1950s to make up for the discrepancies in PCMOs in certain engine families - yes, some poor design issues prevailed then. In particular I settled on HD lubricants that were CAT Supplement 3 (and etc) or MB endorsed. Later other engine makers followed the CAT and MB Approvals process

I have used HD lubricants ever since although today's PCMOs are so good (especially those with suitable ACEA Quality ratings) that they are not "required" in petrol engines

Some points to remember:
a) always use a dual rated HDEO (eg API C?/S?) but never a C? only rating
b) ensure the SA level is suitable (not too high)
c) use the correct viscosity (engine maker defined)
d) use UOAs if the intent is to extend OCIs

Using a diesel specific HDEO with very high SA levels may lead to excessive wear in certain areas such as ring pack/piston

 

[paulswagelock]

Most boats recommend either a 25w-40, 20w-40, or straight 40. I assume a 15w-40 is suitable. Sulfated ash in most of those would be from 1-1.3%.

All are SL or SM rated.

Seem applicable?

 

[Steve S]

I would imagine at WOT the timimg would cut back. Think about it and if you can't figure it out, you probably are over your head stressing about the oil.

 

[paulswagelock]

Originally Posted By: Steve S
I would imagine at WOT the timimg would cut back. Think about it and if you can't figure it out, you probably are over your head stressing about the oil.


I understand how timing works - not the question. The question was if zinc would cause pre-ignition as the poster suggested.

 

[A_Harman]

I worked in the high-performance marine engine biz for 6 years.
I can assure you that most of the builders there are snake-oil salesmen.

The original author of that article had no clue about the role of zinc additives in oil. The knock against using diesel oil in highly-loaded gasoline engines is the high ash content causing deposits in the combustion chambers, leading to preignition and/or detonation. Diesel oils containing magnesium additives for detergency are most suspect for this. But if you don't have an oil consumption problem, why worry?

 

[morris]

this might mean somthing or it may not. went to the cummins/onan dealer today. it get a carb part for an onan engine. they had a brochure from valvoline and cummins. premium blue oil listed lots of specs BUT the zinc content. course both bragged about the premium blue. recomened change interval , severe duty-20,000. normal duty, 35,000. light duty, 45,000. when i saw this it reminded me that diesel engines have different oil filters than most gas engines, so that change interval CANT work in a gas engine. this is only for a cummins diesel engine. lots of bragging about how the two co, they made the two to work together. and the premium blue is the ONLY oil rec omened for the cummins diesel. and is factory fill for it. brochures cf-2272, and cf-2134. edit: on diesel fuel dont use reg mmo, they have mmo made for diesel.

 

[bullwinkle]

Cummins & Valvoline seem to be joined at the hip-er-WALLET! Just about any HDEO seems to work well in the Cummins, but they & Valvoline seem to have a special relationship-and if you look over on the UOA section there's a guy w/a Cummins in a Dodge that is over 25K on one fill of Premium Blue with no problems. Back on topic, when I finally find a decent SBC 350/Mercruiser powered cuddy cabin-if it is a flat tappet motor I'm going to run either 15W40 Delvac 1300 or Premium Blue in it.

 

[Trvlr500]

Too much ZDDP CAN cause problems in an engine from what I have read. It isn't the zinc that "plates" the surfaces as a last ditch protector. It is the Phosphorus. Zinc is the carrier.

You would have to have a VERY high ZDDP level to cause damage over time and in a race engine which is overhauled all the time I doubt it would ever get the chance to do any damage.

I actually read in one article that too much ZDDP will erode bearing surfaces and foul plugs but I highly doubt there is enough in any diesel oil to ever do that.

The HDEO diesel oils have about 1000+ ppm of ZDDP. I run Rotella because I have an old relic which is almost 40 years old and it needs a little more because of the flat tappet lifters and cam. I really only need 800ppm.

I highly doubt zinc is causing the problems mentioned since every racing oil out there is loaded with it up to 1700 ppm and beyond. The street oil bought off the shelf these days is lucky to have 800ppm.

I'm no expert but I have done a LOT of reading on ZDDP because I have an older vehicle that needs it.