Zinc Dithiophosphate

[moondoggie]

Good Day!

Did we ever determine if Power Service Diesel Lube Oil Extender is a good alternative for STP Red, to add some zinc dithiophosphate to our oil, as recommended by the good Dr.? (Reference closed topic Oil Supplement/Synthetic oil????? (Click in colored text).)

Thanks & Blessings!

[rustyk]

Most name-brand diesel motor oils already have zinc dithiophosphate incorporated. Its main purpose is as an anti-scuff compound for cams and cylinder walls.

The comments on the linked page about viscosity index improvers (VI improvers) is a bit off-base. Properly formulated VI improvers don't have the drawbacks mentioned. However, none should be added to a name-brand oil.

[moondoggie]

Good Day!

From what I've read here & elsewhere, the presence of this additive, or something that shows up with it, destroys catalytic converters. So, it has been eliminated from any oil rated for gas engines. I use Synthetic 5W-40 Rotella year-round, which is rated for both gas & diesel engines, so if the above is true, there's no zinc d. in it.

The good Dr. suggested adding STP to our oil to restore this additive was a good idea. What's up? As usual, I'm confused. Are lots of diesel-rated oils NOT rated for gas engines too? Or is the above information in error?



Blessings!

(signature in previous post)

[rustyk]

Demands on the lubricants for diesels and for gaso engines are significantly different, as are the parameters under which each type of engine runs. Gaso engines typically run with compression ratios 10:1 or less, with a fuel with a low flash point. Diesels run 15:1 and up, with a fuel which has a flash point so high, you can't light it with a match at room temp.

Let's start with the STP thing. Unless the formula has been radically changed, STP is predominately polyisobutylene, a very crude viscosity index improver (VII). I won't go into details here, but when it mechanically breaks down, the remaining pieces manifest themselves in hard, gritty deposits in the ring belt and other areas. It has no other constituents that enhance motor oil.

Secondly, motor oil (either gaso or diesel) will clobber a catalytic converter regardless of the additives. Catalytics depend on treating byproducts of fuel combustion, not that of motor oil.

Tests of motor oil, which result in the award of an S-* or C-* rating (like C-C or S-H) are based on lubricating properties, such as high- and low-temp sludge, cam wear, etc. An oil can be rated C-C and S-H if it passes all the applicable tests for both ratings.

Now to a more ticklish issue: Synthetics. My personal opinion is that synthetics are a waste of money on diesels, but not on gaso engines. Modern gaso engines use unleaded fuel, and for the most part, it's rare to find a vehicle that burns a lot of oil (significant blowby). Because of that, gaso engines stress the additive package far less than diesels. I use Mobil 1 in my gaso car.

My 1-ton van (Ford 6.9L NA diesel) and the motorhome (see sig) get Rotella T 15W-40. The reason synthetics are wasted on diesels is that the additive package will be depleted before the base stock starts to deteriorate. With modern gaso engines, it's the reverse. The oil in my car gets changed every six months, and the diesels, every 3 to 4K miles, depending on use.

[moondoggie]

Good Day!


STP: "It has no other constituents that enhance motor oil." Are you saying it doesn't contain zinc dithiophosphate, or the zinc dithiophosphate that it does contain does not do what's been described, a superior anti-wear oil additive?

"...the remaining pieces manifest themselves in hard, gritty deposits in the ring belt and other areas." I'm unconcerned about this - I only add what the good Dr. suggested - 1/2 a bottle, or ~ 7.5 oz. Should I/we still quit adding this small volume of STP?

I was really more interested in other sources of zinc dithiophosphate. If I find a different source, I would quit using STP for this purpose anyway. It appears no one knows this answer.

This has gotten WAY more interesting than I had thought it might be. I can't WAIT for what I learn next.

I happen to agree with your opinion about using synthetic oil in diesels. I did it because when it initially became available at WalMart, it was $12.84 a gallon; with my daughter's 10% discount, I was paying less than $3 a quart. The big benefit is now I only stock one oil for everything. I used to have to stock 10W-30 & 15W-40 for the diesels, & 5W-30 & 10W-30 for the gassers. Yeah, I didn't have to use all of these, just personal preference. I still change oil in all my vehicles at ~ 3K miles, but I'm less concerned than before if it slips to 5K miles.

Blessings!

(signature in previous post)

[rustyk]

STP used to consist of polyisobutylene and a bright base stock.

As for adding STP, there is nothing in my experience to be gained, and as for me, I don't want the ring belt deposits. If you're using a high quality motor oil (Delvac, Rotella T, Kendall Super DIII, etc.) there's no advantage to adding something else to the oil. In the oil biz, these additives are called "mouse milk".

As for zinc dithiophosphate, why would you want to add it? It's probably already in the oil, in the desirable proportion.

[gmctd]

STP has had ZDP as far back as I can remember, and I'm 65.

Dr Lee indicated we should use the STP in the red bottle, with reduced VI for 4-cylinder engines, because 6.5 didn't need VI or the resultant deposits, which would cremate out and turn gritty - that should be good for polishing yer crank, eh?

Take a whiff of STP and you may recognize an old friend, if you use Rotella - I still add 8oz STP every oil change, but my truck doesn't have a catalytic convertor, or the 6.5 soot trap.

As we all know, sulphur will destroy a cat - which is why STP is becoming scarcer than hen's teeth - the 'thio' component is sulphur.

So, what will happen to the new ULSD-ready trucks with their sulphur-sensitive cats, with a crankcase load of ZDP-enhanced oil plus a healthy shot of STP.

Guess they'll be using syn - or VI-dosed water.................

[moondoggie]

Good Day!

"As for zinc dithiophosphate, why would you want to add it?" A man I have a lot of respect for, & seems to have the credentials to back up his recommendations, made this suggestion. Click on the link in my 1st post - that's why I put it there. I appreciate the knowledge I've gained by the posts, but I intend to continue adding a small quantity of STP to each oil change.

What's gotten lost is - I never got my question answered. It's A-OK this sorta became a "don't use STP" topic - I'm grateful for the knowledge, but what I REALLY wanted to know, no one knows.


Blessings!

(signature in previous post)

[Bnave95]

Good Day!

Did we ever determine if Power Service Diesel Lube Oil Extender is a good alternative for STP Red, to add some zinc dithiophosphate to our oil, as recommended by the good Dr.? (Reference closed topic Oil Supplement/Synthetic oil????? (Click in colored text).)

Thanks & Blessings!

Where are you seeing this product?
Don't see it at there web site.
I happen across a old trucking Buss. and found a case of 14 ounce can,reads. This is a old can!
Pennzoil
LOA
Concentrated
Crankcase oil
Additive
Warning label reads-Contains Zinc Dithio Phosphate.

[JeepSJ]

As for zinc dithiophosphate, why would you want to add it? It's probably already in the oil, in the desirable proportion.

Over in the gasser community, camshaft mfgs are recommending a diesel rated oil (some even specifically recommend Rotella T) for camshaft break-in. This is due to the zinc being refined out of the gasser rated oils. The additional zinc helps protect the cam and lifters. GM even has an engine oil supplement that contains zinc.

With cats starting to show up on diesels, it would not surprise me if they started refining the zinc out of the diesel oils.

[moondoggie]

Good Day!

"Where are you seeing this product?" Do you mean Power Service Diesel Lube Oil Extender? I read about it somewhere here on the Page. I think someone proposed it might be another way to add zinc dithiophosphate to our oil.

Blessings!

[Bnave95]

Good Day!

"Where are you seeing this product?" Do you mean Power Service Diesel Lube Oil Extender? I read about it somewhere here on the Page. I think someone proposed it might be another way to add zinc dithiophosphate to our oil.

Blessings!

Yes on the Power Service product. Here is a E-Mail reply

We use to make a product called Diesel Lube Oil Extender and it is an excellent product. It contains Zinc Dialkyldithiophosphate or ZDDP. The Zinc in the product is anti-wear and anti-oxidation in nature. The product is a proprietary complex mixture so I cannot go into more detail about the chemical makeup of the product.

Let me know if you have any questions or concerns.

Best Regards,



Brian Wilson

bwilson@powerservice.com

Compliance Coordinator

Technical Advisor

800-643-9089

[moondoggie]

Good Day!

[FONT=Verdana]Guess I should have read my own link. jbplock